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Usage

How to manage the application with CAP Operator

1: Prerequisites
2: Deploying a CAP Application
3: Tenant Subscription
4: Application Upgrade
5: Version Monitoring
6: Resources

6.1: CAPApplication
6.2: CAPApplicationVersion
6.3: CAPTenant
6.4: CAPTenantOperation
6.5: CAPTenantOutput

1 - Prerequisites

What to do before you deploy a new CAP application

Prepare the SAP BTP global account and provider subaccount

CAP-based applications make use of various SAP BTP services that are created in a provider subaccount. So, before you can deploy the application, create a global account and assign the required services that will be used. To do so, use SAP BTP Control Center. Once done, create a provider subaccount, where the required service instances can be created.

Create service instances and bindings

A multi-tenant CAP-based application consumes the following SAP BTP services. While creating these service instances, some of the parameters supplied require special attention. Service keys (bindings) are then created to generate access credentials, which in turn should be provided as Kubernetes Secrets in the namespace where the application is being deployed.

Other services (not listed here) may also be used depending on the requirement (for example, SAP HTML5 Application Repository service for SAP BTP, Business Logging, and so on).

Note: If some SAP BTP services are not available on Kubernetes, enable Cloud Foundry for the provider subaccount to create certain services. In such cases you may use the cf-service-operator for managing the service instances and service bindings directly from within the Kubernetes cluster. Based on the service bindings, it automatically generates the secrets containing the service access credentials.

SAP Authorization and Trust Management Service

The parameter oauth2-configuration.redirect-uris must include the domain used by the application. For instance, if the application is hosted in a “Gardener” managed cluster, the entry may have the form https://*<application-specific-prefix>.<cluster-id>.<gardener-project-id>.shoot.url.k8s.example.com/**.

Scope required to make asynchronous tenant subscription operations need to be included. Additionally, check the CAP Multitenancy documentation for additional scopes which are required.

parameters:
  authorities:
    - $XSAPPNAME.mtcallback
    - $XSAPPNAME.mtdeployment
  oauth2-configuration:
    redirect-uris:
      - https://*my-cap-app.cluster-x.my-project.shoot.url.k8s.example.com/**
  role-collections:
    ...
  role-templates:
    ...
  scopes:
    - description: UAA
      name: uaa.user
    - description: With this scope set, the callbacks for tenant onboarding, offboarding, and getDependencies can be called
      grant-as-authority-to-apps:
        - $XSAPPNAME(application,sap-provisioning,tenant-onboarding)
      name: $XSAPPNAME.Callback
    - description: Async callback to update the saas-registry (provisioning succeeded/failed)
      name: $XSAPPNAME.subscription.write
    - description: Deploy applications
      name: $XSAPPNAME.mtdeployment
    - description: Subscribe to applications
      grant-as-authority-to-apps:
        - $XSAPPNAME(application,sap-provisioning,tenant-onboarding)
      name: $XSAPPNAME.mtcallback
    ...

When using mulitple SAP Authorization and Trust Management Service instances in the app (for example, one for the application and other apiaccess). The primary instance can be set using the annotation: “sme.sap.com/primary-xsuaa” with the value being the name of the service instance, as shown below:

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplication
metadata:
  annotations:
    "sme.sap.com/primary-xsuaa": "my-cap-app-uaa" # This let's the CAP Operator determine/use the right UAA instance for the application.
  name: test-cap-01
  ...
spec:
  btp:
    services:
      - class: xsuaa
        name: my-cap-app-uaa-api
        secret: my-cap-app-uaa-api-bind-cf
      - class: xsuaa
        name: my-cap-app-uaa
        secret: my-cap-app-uaa-bind-cf
      - class: saas-registry
        name: my-cap-app-saas-registry
        secret: my-cap-app-saas-bind-cf
      ...
  btpAppName: my-cap-app
  ...

SAP Software-as-a-Service Provisioning service

When creating an instance of the SaaS Provisioning service, use asynchronous tenant subscription callbacks in the configuration. See Register Your Multi-Tenant Application/Service in SaaS Provisioning for more details.

parameters:
  appName: <short-application-name>
  appUrls:
    callbackTimeoutMillis: 300000 # <-- used to fail subscription process when no response is received
    getDependencies: https://<provider-subaccount-subdomain>.<cap-app-name>.cluster-x.my-project.shoot.url.k8s.example.com/callback/v1.0/dependencies # <-- handled by the application
    onSubscription: https://<cap-operator-subscription-server-domain>/provision/tenants/{tenantId} # <-- the /provision route is forwarded directly to CAP Operator (Subscription Server) and must be specified as such
    onSubscriptionAsync: true
    onUnSubscriptionAsync: true

SAP HANA Cloud

An SAP HANA Cloud instance (preferably shared and accessible from the provider subaccount) is required. The Instance ID of the database must be noted for usage in relevant workloads. SAP HANA Schemas & HDI Containers service must also be entitled for the provider subaccount.

SAP Service Manager service

The SAP Service Manager service allows CAP to retrieve schema-(tenant-)specific credentials to connect to the SAP HANA Cloud database.

2 - Deploying a CAP Application

How to deploy a new CAP-based application

Just by defining two resources provided by CAP Operator, namely capapplications.sme.sap.com and capapplicationversions.sme.sap.com, it’s possible to deploy a multi-tenant CAP application and start using it. These resources are namespaced and so the CAP Operator will create all related resources (deployments, gateways, jobs etc.) within the same namespace.

The object, CAPApplication, describes the high-level attributes of an application such as the SAP BTP account where it is hosted, the consumed SAP BTP services, domains where the application routes will be made available etc. See API Reference.

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplication
metadata:
  name: cap-app-01
  namespace: cap-app-01
spec:
  btpAppName: cap-app-01 # <-- short name (similar to SAP BTP XSAPPNAME)
  btp:
    services:
      - class: xsuaa # <-- SAP BTP service technical name
        name: app-uaa # <-- name of the service instance
        secret: cap-app-01-uaa-bind-cf # <-- secret containing the credentials to access the service existing in the same namespace
      - class: saas-registry
        name: app-saas-registry
        secret: cap-app-01-saas-bind-cf
      - class: service-manager
        name: app-service-manager
        secret: cap-app-01-svc-man-bind-cf
      - class: destination
        name: app-destination
        secret: cap-app-01-dest-bind-cf
      - class: html5-apps-repo
        name: app-html5-repo-host
        secret: cap-app-01-html5-repo-bind-cf
      - class: html5-apps-repo
        name: app-html5-repo-runtime
        secret: cap-app-01-html5-rt-bind-cf
      - class: portal
        name: app-portal
        secret: cap-app-01-portal-bind-cf
  domains:
    istioIngressGatewayLabels: # <-- labels used to identify the Istio ingress gateway (the values provided here are the default values)
      - name: app
        value: istio-ingressgateway
      - name: istio
        value: ingressgateway
    primary: "cap-app-01.cluster.shoot.url.k8s.example.com" # <-- primary domain where the application is exposed. Each tenant will have access to a subdomain of this domain. Ensure that this is at most 62 chars long.
    secondary:
      - "alt.shoot.example.com"
  globalAccountId: global-account-id
  provider:
    subDomain: cap-app-01-provider
    tenantId: e55d7b5-279-48be-a7b0-aa2bae55d7b5

The object, CAPApplicationVersion, describes the different components of an application version including the container images to be used and the services consumed by each component. See API Reference.

The CAPApplicationVersion must be created in the same namespace as the CAPApplication and refers to it.

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  name: cav-cap-app-01-1
  namespace: cap-app-01
spec:
  capApplicationInstance: cap-app-01 # <-- reference to CAPApplication in the same namespace
  version: "1" # <-- semantic version
  registrySecrets:
    - regcred
  workloads:
    - name: cap-backend
      consumedBTPServices: # <-- these are services used by the application server (already defines as part of CAPApplication resource). Corresponding credential secrets will be mounted onto the component pods as volumes.
        - app-uaa
        - app-service-manager
        - app-saas-registry
      deploymentDefinition:
        type: CAP # <-- indicates the CAP application server
        image: app.some.repo.example.com/srv/server:0.0.1
        env:
          - name: CDS_ENV
            value: production
          - name: CDS_MTX_PROVISIONING_CONTAINER
            value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
    - name: app-router
      consumedBTPServices:
        - app-uaa
        - app-destination
        - app-saas-registry
        - app-html5-repo-runtime
        - app-portal
      deploymentDefinition:
        type: Router
        image: app.some.repo.example.com/approuter/approuter:0.0.1
        env:
          - name: PORT
            value: 4000
          - name: TENANT_HOST_PATTERN
            value: "^(.*).(cap-app-01.cluster.shoot.canary.k8s-hana.ondemand.co|alt.shoot.example.com)"
    - name: service-content
      consumedBTPServices:
        - app-uaa
        - app-html5-repo-host
        - app-portal
      jobDefinition:
        type: Content
        image: app.some.repo.example.com/approuter/content:0.0.1
        backoffLimit: 1

NOTE: The example above is a minimal CAPApplicationVersion that can be deployed. For a more supported configuration and their explanations, see here.

The controller component of CAP Operator reacts to these objects and creates further resources, which constitute a running application:

Deployment (and service) for the application server with credentials (from secrets) to access SAP BTP services injected as VCAP_SERVICES environment variable
Deployment (and service) for the approuter with destination mapping to the application server and subscription server (for the tenant provisioning route)
Job for the version content deployer
TLS certificates for the domains provided using either “Gardener” cert-management or cert-manager.io cert-manager
Istio gateway resource for the application domains

The content deployer is used to deploy content or configuration to SAP BTP services, before using them.

Once these resources are available, the CAPApplicationVersion status changes to Ready. The controller proceeds to automatically create an object of type CAPTenant, which corresponds to the tenant of the provider subaccount. Please see tenant subscription for details on how the CAPTenant resource is reconciled.

The CAPApplicationVersion resource is meant to be immutable - it’s spec should not be modified once it is deployed. This is also prevented by our web-hooks which we recommend to always keep active (default).

3 - Tenant Subscription

How tenant provisioning works

From the perspective of CAP Operator, a valid tenant for an application is represented by the resource CAPTenant. It refers to the CAPApplication it belongs to and specifies the details of the SAP BTP subaccount representing the tenant.

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenant
metadata:
  name: cap-app-01-provider
  namespace: cap-app-01
spec:
  capApplicationInstance: cap-app-01 # <-- reference to the CAPApplication
  subDomain: app-provider
  tenantId: aa2bae55d7b5-1279-456564-a7b0-aa2bae55d7b5
  version: "1.0.0" # <-- expected version of the application
  versionUpgradeStrategy: always # <-- always / never

Tenant Provisioning

The process of tenant provisioning starts when a consumer subaccount subscribes to the application, either via the SAP BTP cockpit or using the APIs provided by the SaaS provisioning service. This, in turn, initiates the asynchronous callback from the SaaS provisioning service instance into the cluster, and the request is handled by the subscription server. The subscription server validates the request and creates an instance of CAPTenant for the identified CAPApplication.

Warning

An instance of CAPTenant must not be created or deleted manually within the cluster. A new instance has to be created by the subscription server after receiving a provisioning call from SaaS provisioning service.

The controller, observing the new CAPTenant, will initiate the provisioning process by creating the resource CAPTenantOperation, which represents the provisioning operation.

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenantOperation
metadata:
  name: cap-app-01-provider-sgz8b
  namespace: cap-app-01
spec:
  capApplicationVersionInstance: cav-cap-app-01-1 # <-- latest CAPApplicationVersion in Ready state
  subDomain: app-provider
  tenantId: aa2bae55d7b5-1279-456564-a7b0-aa2bae55d7b5
  operation: provisioning # <-- valid values are provisioning, deprovisioning and upgrade
  steps:
    - name: cap-backend # <-- derived from workload of type CAP (when workload of type TenantOperation is not specified)
      type: TenantOperation

The CAPTenantOperation is further reconciled to create Kubernetes jobs (steps), which are derived from the latest CAPApplicationVersion, which is in Ready state. The steps comprise of a TenantOperation job and optional CustomTenantOperation steps. The TenantOperation step uses built in CLI-based tenant operations from @sap/cds-mtxs to execute tenant provisioning.

The CAPTenant reaches a Ready state, only after

a successful completion of all CAPTenantOperation steps.
the creation of Istio VirtualService, which allows HTTP requests on the tenant subdomain to reach the application.

tenant-provisioning

Tenant Deprovisioning

Similar to the tenant provisioning process, when a tenant unsubscribes from the application, the request is received by the subscription server. It validates the existence and status of the CAPTenant and submits a request for deletion to the Kubernetes API server.

The controller identifies that the CAPTenant has to be deleted, but withholds deletion until it can create and watch for a successful completion of a CAPTenantOperation of type deprovisioning. The CAPTenantOperation creates the corresponding jobs (steps), which execute the tenant deprovisioning.

4 - Application Upgrade

How to upgrade to a new Application Version

An important lifecycle aspect of operating multi-tenant CAP applications is the tenant upgrade process. With CAP Operator, these tenant upgrades can be fully automated by providing a new instance of the capapplicationversions.sme.sap.com custom resource. As you’ve already seen during the initial deployment, the CAPApplicationVersion resource describes the different components (workloads) of an application version that includes the container image to be used and the services consumed by each component. To upgrade the application, provide a new CAPApplicationVersion with the relevant image for each component and use a newer (higher) semantic version in the version field. See API Reference.

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  name: cav-cap-app-01-2
  namespace: cap-app-01
spec:
  capApplicationInstance: cap-cap-app-01 # <-- reference to CAPApplication in the same namespace
  version: "2.0.1" # <-- semantic version
  registrySecrets:
    - regcred
  workloads:
    - name: cap-backend
      consumedBTPServices:
        - app-uaa
        - app-service-manager
        - app-saas-registry
      deploymentDefinition:
        type: CAP # <-- indicates the CAP application server
        image: app.some.repo.example.com/srv/server:0.0.2
        env:
          - name: CDS_ENV
            value: production
          - name: CDS_MTX_PROVISIONING_CONTAINER
            value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
    - name: app-router
      consumedBTPServices:
        - app-uaa
        - app-destination
        - app-saas-registry
        - app-html5-repo-runtime
        - app-portal
      deploymentDefinition:
        type: Router
        image: app.some.repo.example.com/approuter/approuter:0.0.2
        env:
          - name: PORT
            value: 4000
          - name: TENANT_HOST_PATTERN
            value: "^(.*).(cap-app-01.cluster.shoot.canary.k8s-hana.ondemand.co|alt.shoot.example.com)"
    - name: service-content
      consumedBTPServices:
        - app-uaa
        - app-html5-repo-host
        - app-portal
      jobDefinition:
        type: Content
        image: app.some.repo.example.com/approuter/content:0.0.2
        backoffLimit: 1
    - name: tenant-operation
      consumedBTPServices:
        - app-uaa
        - app-service-manager
        - app-saas-registry
      jobDefinition:
        type: TenantOperation
        image: app.some.repo.example.com/approuter/content:0.0.2
        env:
          - name: CDS_ENV
            value: production
          - name: CDS_MTX_PROVISIONING_CONTAINER
            value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
    - name: notify-upgrade
      consumedBTPServices: []
      jobDefinition:
        type: CustomTenantOperation
        image: app.some.repo.example.com/approuter/content:0.0.2
        command: ["npm", "run", "notify:upgrade"]
        backoffLimit: 1
        env:
          - name: TARGET_DL
            value: group_xyz@sap.com
  tenantOperations:
    upgrade:
      - workloadName: tenant-operation
      - workloadName: notify-upgrade
        continueOnFailure: true

Note that in this version (compared to version “1” used for the initial deployment), new workloads of type TenantOperation and CustomTenantOperation have been added.

The controller component of CAP Operator reacts to the new CAPApplicationVersion resource and triggers another deployment for the application server, router and triggers the content deployment job. Once the new CAPApplicationVersion is Ready, the controller proceeds to automatically upgrade all relevant tenants i.e. by updating the version attribute on the CAPTenant resources.

The reconciliation of a CAPTenant changes its state to Upgrading and creates the CAPTenantOperation resource of type upgrade.

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenantOperation
metadata:
  name: cap-app-01-provider-fgdfg
  namespace: cap-app-01
spec:
  capApplicationVersionInstance: cav-cap-app-01-2
  subDomain: cap-provider
  tenantId: aa2bae55d7b5-1279-456564-a7b0-aa2bae55d7b5
  operation: upgrade # possible values are provisioning / upgrade / deprovisioning
  steps:
    - name: "tenant-operation"
      type: TenantOperation
    - name: "notify-upgrade"
      type: CustomTenantOperation
      continueOnFailure: true # <-- can be set for workloads of type CustomTenantOperation to indicate that the success of this job is optional for the completion of the overall operation

The CAPTenantOperation creates jobs for each of the steps involved and executes them sequentially until all the jobs are finished or one of them fails. The CAPTenant is notified about the result and updates its state accordingly.

A successful completion of the CAPTenantOperation will cause the VirtualService managed by the CAPTenant to be modified to route HTTP traffic to the deployments of the newer CAPApplicationVersion. Once all tenants have been upgraded, the outdated CAPApplicationVersion can be deleted.

5 - Version Monitoring

How to monitor versions for automatic cleanup

In a continuous delivery environment where newer applications versions may be deployed frequently, monitoring and cleaning up older unused versions becomes important to conserve cluster resources (compute, memory, storage etc.) and operate a clutter free system. The CAP Operator now provides application developers and operations teams to define how an application version can be monitored for usage.

Integration with Prometheus

Prometheus is the industry standard for monitoring application metrics and provides a wide variety of tools for managing and reporting metrics data. The CAP Operator (controller) can be connected to a Prometheus server by setting the PROMETHEUS_ADDRESS environment variable on the controller (see Configuration). The controller is then able to query application related metrics based on the workload specification of CAPApplicationVersions. If no Prometheus address is supplied, the version monitoring function of the controller is not started.

Configure `CAPApplication`

To avoid incompatible changes, version cleanup monitoring must be enabled for CAP application using the annotation sme.sap.com/enable-cleanup-monitoring. The annotation can have the following values which affects the version cleanup behavior:

Value	Behavior
`dry-run`	When a `CAPApplicationVersion` is evaluated to be eligible for cleanup, an event of type `ReadyForDeletion` is emitted without performing the actual deletion of the version.
`true`	When a `CAPApplicationVersion` is evaluated to be eligible for cleanup, the version is deleted and an event of type `ReadyForDeletion` is emitted.

Configure `CAPApplicationVersion`

For each workload of type deployment in a CAPApplicationVersion, it is possible to define:

Deletion rules: A criteria based on metrics which when satisfied signifies that the workload can be removed
Scrape configuration: Configuration which defines how metrics are scraped from the workload service.

Deletion Rules (Variant 1) based on Metric Type

The following example shows how a workload, named backend, is configured with deletion rules based on multiple metrics.

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  namespace: demo
  name: cav-demo-app-1
spec:
  workloads:
    - name: backend
      deploymentDefinition:
        monitoring:
          deletionRules:  
            metrics:
              - calculationPeriod: 90m
                name: current_sessions
                thresholdValue: "0"
                type: Gauge
              - calculationPeriod: 2h
                name: total_http_requests
                thresholdValue: "0.00005"
                type: Counter

This informs the CAP Operator that workload backend is supplying two metrics which can be monitored for usage.

Metric current_sessions is of type Gauge which indicates that it is an absolute value at any point of time. When evaluating this metric, the CAP operator queries Prometheus with a PromQL expression which calculates the average value of this metric over a specified calculation period. The average value from each time series is then added together to get the evaluated value. The evaluated value is then compared against the specified threshold value to determine usage (or eligibility for cleanup).

Evaluation steps for metric type `Gauge`
Execute PromQL expression `sum(avg_over_time(current_sessions{job="cav-demo-app-1-backend-svc",namespace="demo"}[90m]))` to get the evaluated value
Check whether evaluated value <= 0 (the specified `thresholdValue`)

Similarly, metric total_http_requests is of type Counter which indicates that it is a cumulative value which can increment. When evaluating this metric, the CAP operator queries Prometheus with a PromQL expression which calculates the rate (of increase) of this metric over a specified calculation period. The rate of increase from each time series is then added together to get the evaluated value. The evaluated value is then compared against the specified threshold value to determine usage (or eligibility for cleanup).

Evaluation steps for metric type `Counter`
Execute PromQL expression `sum(rate(total_http_requests{job="cav-demo-app-1-backend-svc",namespace="demo"}[2h]))` to get the evaluated value
Check whether evaluated value <= 0.00005 (the specified `thresholdValue`)

Prometheus Metrics Data

Prometheus stores metric data as multiple time series by label set. The number of time series created from a single metric depends on the possible combination of labels. The label job represents the source of the metric and (within Kubernetes) is the service representing the workload.
CAP Operator does not support Prometheus metric types other than Gauge and Counter. Lean more about metric types here.

All specified metrics of a workload must satisfy the evaluation criteria for the workload to be eligible for cleanup.

Deletion Rules (Variant 2) as PromQL expression

Another way to specify the deletion criteria for a workload is by providing a PromQL expression which results a boolean scalar.

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  namespace: demo
  name: cav-demo-app-1
spec:
  workloads:
    - name: backend
      deploymentDefinition:
        monitoring:
          deletionRules:
            expression: scalar(sum(avg_over_time(current_sessions{job="cav-demo-app-1-backend-svc",namespace="demo"}[2h]))) <= bool 5

The supplied PromQL expression is executed as a Prometheus query by the CAP Operator. The expected result is a scalar boolean (0 or 1). Users may use comparison binary operators with the bool modifier to achieve the expected result. If the evaluation result is true (1), the workload is eligible for removal.

This variant can be useful when:

the predefined evaluation based on metric types is not enough for determining usage of a workload.
custom metrics scraping configurations are employed where the job label in the collected time series data does not mach the name of the (Kubernetes) Service created for the workload.

Scrape Configuration

Prometheus Operator is a popular Kubernetes operator for managing Prometheus and related monitoring components. A common way to setup scrape targets for a Prometheus instance is by creating the ServiceMonitor resource which specifies which Services (and ports) that should be scraped for collecting application metrics.

Prerequisite

The scrapeConfig feature of a workload is usable only when the ServiceMonitor Custom Resource is available on the Kubernetes cluster.

The CAP Operator provides an easy way to create Service Monitors which target the Services created for version workloads. The following sample shows how to configure this.

kind: CAPApplicationVersion
metadata:
  namespace: demo
  name: cav-demo-app-1
spec:
  workloads:
    - name: backend
      deploymentDefinition:
        ports:
          - appProtocol: http
            name: metrics-port
            networkPolicy: Cluster
            port: 9000
        monitoring:
          deletionRules:
            expression: scalar(sum(avg_over_time(current_sessions{job="cav-demo-app-1-backend-svc",namespace="demo"}[2h]))) <= bool 5
          scrapeConfig:
            interval: 15s
            path: /metrics
            port: metrics-port

With this configuration the CAP Operator will create a ServiceMonitor which targets the workload Service. The scrapeConfig.port should match the name of one of the ports specified on the workload.

Use Case

The workload scrapeConfig aims to support a minimal configuration, creating a ServiceMonitor which supports the most common use case (i.e. scraping the workload service via. a defined workload port). To use complex configurations in ServiceMonitors, they should be created separately. If the scrapeConfig of a version workload is empty, the CAP Operator will not attempt to create the related ServiceMonitor.

Evaluating `CAPApplicationVersions` for cleanup

At specified intervals (dictated by controller environment variable METRICS_EVAL_INTERVAL), the CAP Operator selects versions which are candidates for evaluation.

Only versions for CAPApplications where annotation sme.sap.com/enable-cleanup-monitoring is set are considered.
All versions (spec.version) higher than the highest version with Ready status are not considered for evaluation. If there is no version with status Ready, no versions are considered.
All versions linked to a CAPTenant are excluded from evaluation. This includes versions where the following fields of a CAPTenant point to the version:
- status.currentCAPApplicationVersionInstance - current version of the tenant.
- spec.version - the version to which a tenant is upgrading.

Workloads from the identified versions are then evaluated based on the defined deletionRules. Workloads without deletionRules are automatically eligible for cleanup. All workloads (with type deployment) of a version must satisfy the evaluation criteria for the version to be deleted.

6 - Resources

Detailed configuration of resources managed by CAP Operator

6.1 - CAPApplication

How to configure the CAPApplication resource

Here’s an example of a fully configured CAPApplication:

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplication
metadata:
  name: cap-app
  namespace: cap-ns
spec:
  btp:
    services:
      - class: xsuaa
        name: cap-uaa
        secret: cap-uaa-bind
      - class: saas-registry
        name: cap-saas-reg
        secret: cap-saas-reg-bind
      - class: service-manager
        name: cap-service-manager
        secret: cap-svc-man-bind
      - class: destination
        name: cap-destination
        secret: cap-bem-02-dest-bind
      - class: html5-apps-repo
        name: cap-html5-repo-host
        secret: cap-html5-repo-bind
      - class: html5-apps-repo
        name: cap-html5-repo-runtime
        secret: cap-html5-rt-bind
      - class: portal
        name: cap-portal
        secret: cap-portal-bind
      - class: business-logging
        name: cap-business-logging
        secret: cap-business-logging-bind
  btpAppName: cap-app
  domains:
    istioIngressGatewayLabels: # <-- labels used to identify Load Balancer service used by Istio
      - name: app
        value: istio-ingressgateway
      - name: istio
        value: ingressgateway
    primary: cap-app.cluster.project.shoot.url.k8s.example.com
    secondary:
      - alt-cap.cluster.project.shoot.url.k8s.example.com
  globalAccountId: 2dddd48d-b45f-45a5-b861-a80872a0c8a8
  provider: # <-- provider tenant details
    subDomain: cap-app-provider
    tenantId: 7a49218f-c750-4e1f-a248-7f1cefa13010

The overall list of SAP BTP service instances and respective Secrets (credentials) required by the application is specified as an array in btp.services. These service instances are assumed to exist in the provider subaccount. Operators such as cf-service-operator or sap-btp-service-operator can be used to declaratively create these service instances and their credentials as Kubernetes resources.

The provider section specifies details of the provider subaccount linked to this application, while globalAccountId denotes the global account in which the provider subaccount is created. Within a global account, the btpAppName has to be unique as this is equivalent to XSAPPNAME, which is used in various SAP BTP service and application constructs.

The domains section provides details of where the application routes are exposed. Within a “Gardener” cluster, the primary application domain is a subdomain of the cluster domain, and “Gardener” cert-management will be used to request a wildcard TLS certificate for the primary domain. Additional secondary domains may also be specified (for example, for customer-specific domains) for the application.

NOTE: While the same secondary domain can technically be used across applications; the consumers need to ensure that the tenant sub-domains are unique across such applications that share the same domain!

istioIngressGatewayLabels are key-value pairs (string) used to identify the ingress controller component of Istio and the related load balancer service. These values are configured during the installation of Istio service mesh in the cluster.

6.2 - CAPApplicationVersion

How to configure the CAPApplicationVersion resource

The CAPApplicationVersion has the following high level structure:

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  name: cav-cap-app-v1
  namespace: cap-ns
spec:
  version: 3.2.1 # <-- semantic version (must be unique within the versions of a CAP application)
  capApplicationInstance: cap-app
  registrySecrets: # <-- image pull secrets to be used in the workloads
    - regcred
  workloads: # <-- define deployments and jobs used for this application version
    - name: "cap-backend"
      deploymentDefinition: # ...
      consumedBTPServices: # ...
    - name: "app-router"
      deploymentDefinition: # ...
      consumedBTPServices: # ...
    - name: "service-content"
      jobDefinition: # ...
      consumedBTPServices: # ...
    - name: "tenant-operation"
      jobDefinition: # ...
      consumedBTPServices: # ...
  tenantOperations: # ... <-- (optional)

An instance of CAPApplicationVersion is always related to an instance of CAPApplication in the same namespace. This reference is established using the attribute capApplicationInstance.
An array of workloads (workloads) must be defined that include the various software components of the SAP Cloud Application Programming Model application. A deployment representing the CAP application server or a job that which is used for tenant operations are examples of such workloads. A workload must have either a deploymentDefinition or a jobDefinition. See the next section for more details.
An optional attribute tenantOperations can be used to define a sequence of steps (jobs) to be executed during tenant operations (provisioning / upgrade / deprovisioning).

The CAPApplicationVersion resource is meant to be immutable - it’s spec should not be modified once it is deployed. This is also prevented by our web-hooks which we recommend to always keep active (default).

Workloads with `deploymentDefinition`

name: cap-backend
consumedBTPServices: # <-- an array of service instance names referencing the SAP BTP services defined in the CAPApplication resource
  - cap-uaa
  - cap-saas-reg
deploymentDefinition:
  type: CAP # <-- possible values are CAP / Router / Additional
  image: some.repo.example.com/cap-app/server:3.22.11 # <-- container image
  env: # <-- (optional) same as in core v1 pod.spec.containers.env
    - name: SAY
      value: "I'm GROOT"
  replicas: 3 # <-- (optional) replicas for scaling
  ports:
    - name: app-port
      port: 4004
      routerDestinationName: cap-server-url
    - name: tech-port
      port: 4005
  monitoring:
    scrapeConfig:
      port: tech--port
    deletionRules:
      expression: scalar(sum(avg_over_time(current_sessions{job="cav-cap-app-v1-cap-backend-svc",namespace="cap-ns"}[2h]))) <= bool 5

The type of the deployment is important to indicate how the operator handles this workload (for example, injection of destinations to be used by the approuter). Valid values are:

CAP to indicate a CAP application server. Only one workload of this type can be used at present.
Router to indicate a version of AppRouter. Only one workload of this type can be used.
Additional to indicate supporting components that can be deployed along with the CAP application server.

You can define optional attributes such as replicas, env, resources, probes, securityContext, initContainers and ports to configure the deployment.

Port configuration

It’s possible to define which (and how many) ports exposed by a deployment container are exposed inside the cluster (via services of type ClusterIP). The port definition includes a name in addition to the port number being exposed.

For deploymentDefinition, other than type Router it would be possible to specify a routerDestinationName which would be used as a named destination injected into the approuter.

The port configurations aren’t mandatory and can be omitted. This would mean that the operator will configure services using defaults. The following defaults are applied if port configuration is omitted:

For workload of type CAP, the default port used by CAP, 4004, will be added to the service and a destination with name srv-api will be added to the approuter referring to this service port (any existing destinations environment configuration for this workload will be taken over by overwriting the URL).
For workload of type Router, the port 5000 will be exposed in the service. This service will be used as the target for HTTP traffic reaching the application domain (domains are specified within the CAPApplication resource).

NOTE: If multiple ports are configured for a workload of type Router, the first available port will be used to target external traffic to the application domain.

Monitoring configuration

For each workload of type deployment in a CAPApplicationVersion, it is possible to define:

Deletion rules: A criteria based on metrics which when satisfied signifies that the workload can be removed
Scrape configuration: Configuration which defines how metrics are scraped from the workload service.

Details of how to configure workload monitoring can be found here.

Workloads with `jobDefinition`

workloads:
  # ... deployment workloads have been omitted in this example
  - name: "content-deployer"
    consumedServices: # ...
    jobDefinition:
      type: Content
      image: some.repo.example.com/cap-app/content:1.0.1
  - name: "tenant-operation"
    consumedServices: # ...
    jobDefinition:
      type: TenantOperation
      image: some.repo.example.com/cap-app/server:3.22.11
      backoffLimit: 2 # <-- determines retry attempts for the job on failure (default is 6)
      ttlSecondsAfterFinished: 300 # <-- the job will be cleaned up after this duration
      env:
        - name: CDS_ENV
          value: production
        - name: CDS_MTX_PROVISIONING_CONTAINER
          value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
  - name: "notify-upgrade"
    consumedServices: # ...
    jobDefinition:
      type: CustomTenantOperation
      image: # ...
      command: ["npm", "run", "notify:upgrade"] # <-- custom entry point for the container allows reuse of a container image with multiple entry points
      backoffLimit: 1
  - name: "create-test-data"
    consumedServices: # ...
    jobDefinition:
      type: CustomTenantOperation
      image: # ...
      command: ["npm", "run ", "deploy:testdata"]

Workloads with a jobDefinition represent a job execution at a particular point in the lifecycle of the application or tenant. The following values are allowed for type in such workloads:

Content: A content deployer job that can be used to deploy (SAP BTP) service specific content from the application version. This job is executed as soon as a new CAPApplicationVersion resource is created in the cluster. Multiple workloads of this type may be defined in the CAPApplicationVersion and the order in which they are executed can be specified via ContentJobs.
TenantOperation: A job executed during provisioning, upgrade, or deprovisioning of a tenant (CAPTenant). These jobs are controlled by the operator and use the cds/mtxs APIs to perform HDI content deployment by default. If a workload of type TenantOperation isn’t provided as part of the CAPApplicationVersion, the workload with deploymentDefinition of type CAP will be used to determine the jobDefinition (image, env, etc.). Also, if cds/mtxs APIs are used, command can be used by applications to trigger tenant operations with custom command.
CustomTenantOperation: An optional job which runs before or after the TenantOperation where the application can perform tenant-specific tasks (for example, create test data).

Sequencing tenant operations

A tenant operation refers to provisioning, upgrade or deprovisioning which are executed in the context of a CAP application for individual tenants (i.e. using the cds/mtxs or similar modules provided by CAP). Within the workloads, we have already defined two types of jobs that are valid for such operations, namely TenantOperation and CustomTenantOperation.

The TenantOperation is mandatory for all tenant operations.

In addition, you can choose which CustomTenantOperation jobs run for a specific operation and in which order. For example, a CustomTenantOperation deploying test data to the tenant database schema would need to run during provisioning, but must not run during deprovisioning.

The field tenantOperations specifies which jobs are executed during the different tenant operations and the order they are executed in.

spec:
  workloads: # ...
  tenantOperations:
    provisioning:
      - workloadName: "tenant-operation"
      - workloadName: "create-test-data"
    upgrade:
      - workloadName: "notify-upgrade"
        continueOnFailure: true # <-- indicates the overall operation may proceed even if this step fails
      - workloadName: "tenant-operation"
      - workloadName: "create-test-data"
    # <-- as the deprovisioning steps are not specified, only the `TenantOperation` workload (first available) will be executed

In the example above, for each tenant operation, not only are the valid jobs (steps) specified, but also the order in which they are to be executed. Each step in an operation is defined with:

workloadNamerefers to the job workload executed in this operation step
continueOnFailure is valid only for CustomTenantOperation steps and indicates whether the overall tenant operation can proceed when this operation step fails.

NOTE:
Specifying tenantOperations is required only if CustomTenantOperations are to be used. If not specified, each operation will comprise of only the TenantOperation step (the first one available from workloads).
The tenantOperations and specified sequencing are valid only for tenants provisioned (or deprovisioned) on the corresponding CAPApplicationVersion and for tenants being upgraded to this CAPApplicationVersion.

Sequencing content jobs

When you create a CAPApplicationVersion workload, you can define multiple content jobs. The order in which these jobs are executed is important, as some jobs may depend on the output of others. The ContentJobs property allows you to specify the order in which content jobs are executed.

spec:
  workloads: # ...
  tenantOperations: # ...
  contentJobs:
    - content-deployer-service
    - content-deployer-ui

Full Example

apiVersion: sme.sap.com/v1alpha1
kind: CAPApplicationVersion
metadata:
  name: cav-cap-app-v1
  namespace: cap-ns
spec:
  version: 3.2.1
  capApplicationInstance: cap-app
  registrySecrets:
    - regcred
  workloads:
    - name: cap-backend
      consumedBTPServices:
        - cap-uaa
        - cap-service-manager
        - cap-saas-reg
      deploymentDefinition:
        type: CAP
        image: some.repo.example.com/cap-app/server:3.22.11
        env:
          - name: CDS_ENV
            value: production
          - name: CDS_MTX_PROVISIONING_CONTAINER
            value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
        replicas: 3
        ports:
          - name: app-port
            port: 4004
            routerDestinationName: cap-server-url
          - name: tech-port
            port: 4005
            appProtocol: grpc
        monitoring:
          scrapeConfig:
            port: tech--port
          deletionRules:
            expression: scalar(sum(avg_over_time(current_sessions{job="cav-cap-app-v1-cap-backend-svc",namespace="cap-ns"}[2h]))) <= bool 5
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /
            port: 4005
          initialDelaySeconds: 20
          periodSeconds: 10
          timeoutSeconds: 2
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /
            port: 4005
          initialDelaySeconds: 20
          periodSeconds: 10
          timeoutSeconds: 2
        resources:
          limits:
            cpu: 200m
            memory: 500Mi
          requests:
            cpu: 20m
            memory: 50Mi
        securityContext:
          runAsUser: 1000
          runAsGroup: 2000
    - name: "app-router"
      consumedBTPServices:
        - cap-uaa
        - cap-saas-reg
        - cap-html5-repo-rt
      deploymentDefinition:
        type: Router
        image: some.repo.example.com/cap-app/router:4.0.1
        env:
          - name: PORT
            value: "3000"
        ports:
          - name: router-port
            port: 3000
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /
            port: 3000
          initialDelaySeconds: 20
          periodSeconds: 10
          timeoutSeconds: 2
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /
            port: 3000
          initialDelaySeconds: 20
          periodSeconds: 10
          timeoutSeconds: 2
        resources:
          limits:
            cpu: 200m
            memory: 500Mi
          requests:
            cpu: 20m
            memory: 50Mi
        podSecurityContext:
          runAsUser: 2000
          fsGroup: 2000
    - name: "service-content"
      consumedServices:
        - cap-uaa
        - cap-portal
        - cap-html5-repo-host
      jobDefinition:
        type: Content
        image: some.repo.example.com/cap-app/content:1.0.1
        securityContext:
          runAsUser: 1000
          runAsGroup: 2000
    - name: "ui-content"
      consumedServices:
        - cap-uaa
        - cap-portal
        - cap-html5-repo-host
      jobDefinition:
        type: Content
        image: some.repo.example.com/cap-app/ui-content:1.0.1
        securityContext:
          runAsUser: 1000
          runAsGroup: 2000
    - name: "tenant-operation"
      consumedServices: # ...
      jobDefinition:
        type: TenantOperation
        image: some.repo.example.com/cap-app/server:3.22.11
        backoffLimit: 2
        ttlSecondsAfterFinished: 300
        env:
          - name: CDS_ENV
            value: production
          - name: CDS_MTX_PROVISIONING_CONTAINER
            value: '{"provisioning_parameters": { "database_id": "16e25c51-5455-4b17-a4d7-43545345345"}}'
    - name: "notify-upgrade"
      consumedServices: []
      jobDefinition:
        type: CustomTenantOperation
        image: some.repo.example.com/cap-app/server:3.22.11
        command: ["npm", "run", "notify:upgrade"]
        backoffLimit: 1
    - name: "create-test-data"
      consumedServices:
        - cap-service-manager
      jobDefinition:
        type: CustomTenantOperation
        image: some.repo.example.com/cap-app/server:3.22.11
        command: ["npm", "run ", "deploy:testdata"]
  tenantOperations:
    provisioning:
      - workloadName: "tenant-operation"
      - workloadName: "create-test-data"
    upgrade:
      - workloadName: "notify-upgrade"
        continueOnFailure: true
      - workloadName: "tenant-operation"
      - workloadName: "create-test-data"
  contentJobs:
    - service-content
    - ui-content

NOTE: The CAP Operator workloads supports several configurations (present in the kubernetes API), which can be configured by looking into our API reference:
Container API reference for generic container-specific configuration
Deployment API reference for deployment-specific configuration
Job API reference for job-specific configuration
The supported configurations is kept minimal intentionally to keep the overall API simple by considering commonly used configurations.

Note: For initContainers nearly the same environment variables as the main container are made available including VCAP_SERVICES environment.

6.3 - CAPTenant

How to configure the CAPTenant resource

Warning

The CAPTenant resource is completely managed by CAP Operator and must not be created or modified manually. For details of how CAPTenant is created, see tenant subscription.

The CAPTenant resource indicates the existence of a tenant in the related application (or one that is current being provisioned). The resource starts with a Provisioning state and moves to Ready when successfully provisioned. Managing tenants as Kubernetes resources allows you not only to control the lifecycle of the entity, but also allows you to control other requirements that must be fulfilled for the application to serve tenant-specific requests (for example, creating of networking resources).

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenant
metadata:
  name: cap-app-consumer-ge455
  namespace: cap-ns
spec:
  capApplicationInstance: cap-app
  subDomain: consumer-x
  tenantId: cb46733-1279-48be-fdf434-aa2bae55d7b5
  version: "1"
  versionUpgradeStrategy: always

The specification contains attributes relevant for SAP BTP, which identifies a tenant such as tenantId and subDomain.

The version field corresponds to the CAPApplicationVersion on which the tenant is provisioned or was upgraded. When a newer CAPApplicationVersion is available, the operator automatically increments the tenant version, which triggers the upgrade process. The versionUpgradeStrategy is by default always, but can be set to never in exceptional cases to prevent an automatic upgrade of the tenant.

6.4 - CAPTenantOperation

How to configure the CAPTenantOperation resource

Warning

The CAPTenantOperation resource is managed by CAP Operator and must not be created or modified manually. The creation of CAPTenantOperation is initiated by the CAPTenant for executing provisioning, deprovisioning, or upgrade.

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenantOperation
metadata:
  name: cap-app-consumer-ge455-77kb9
  namespace: cap-ns
spec:
  capApplicationVersionInstance: cav-cap-app-v2
  operation: upgrade
  steps:
    - continueOnFailure: true
      name: tenant-operation
      type: CustomTenantOperation
    - name: tenant-operation
      type: TenantOperation
    - name: create-test-data
      type: CustomTenantOperation
  subDomain: consumer-x
  tenantId: cb46733-1279-48be-fdf434-aa2bae55d7b5

The example above shows a CAPTenantOperation created to execute an upgrade operation on a tenant. In addition to tenant details, the CAPApplicationVersion to be used for the operation is specified. In case of upgrade or a provisioning operation, this would be the target CAPApplicationVersion whereas for deprovisioning, it would be the current CAPApplicationVersion of the tenant.

The operation is completed by executing a series of steps (jobs) which are specified in or derived from the CAPApplicationVersion. Each step refers to a workload of type TenantOperation or CustomTenantOperation. When CAPTenantOperation is created by CAP Pperator, there must be at least one step of type TenantOperation (which is the job used for the database schema update using CAP provided modules).

CustomTenantOperation jobs are hooks provided to the application, which can be executed before or after the actual TenantOperation. For applications to be able to identify the context of an execution, each job is injected with the following environment variables:

CAPOP_APP_VERSION: The (semantic) version from the relevant CAPApplicationVersion
CAPOP_TENANT_ID: Tenant identifier of the tenant for which the operation is executed
CAPOP_TENANT_OPERATION: The type of operation - provisioning, deprovisioning, or upgrade
CAPOP_TENANT_SUBDOMAIN: Subdomain (from subaccount) belonging to the tenant for which the operation is executed
CAPOP_TENANT_TYPE: The type of tenant - provider or consumer
CAPOP_APP_NAME: The BTP App Name from the corresponding CAPApplication configuration
CAPOP_GLOBAL_ACCOUNT_ID: The Global Account Identifier from the corresponding CAPApplication configuration
CAPOP_PROVIDER_TENANT_ID: The provider tenant identifier from the corresponding CAPApplication configuration
CAPOP_PROVIDER_SUBDOMAIN: The provider tenant subdomain from the corresponding CAPApplication configuration

Note that all of the above environment variables are also made available on the corresponding initContainers (along with other relevant VCAP_SERVICES credentials)

6.5 - CAPTenantOutput

How to configure the CAPTenantOutput resource

The CAPTenantOutput may be used to add additional data to the asynchronous callback parameters from the SaaS provisioning service during tenant onboarding. The resource is not reconciled but just consumed by the subscription server to generate additional data. It has the following structure:

apiVersion: sme.sap.com/v1alpha1
kind: CAPTenantOutput
metadata:
  name: cap-app-consumer-output
  namespace: cap-ns
  labels:
    sme.sap.com/btp-tenant-id: cb46733-1279-48be-fdf434-aa2bae55d7b5
spec:
  subscriptionCallbackData: '{foo: bar}'

The example above shows an instance of the resource that is associated with a tenant via the sme.sap.com/btp-tenant-id label (which must be set by consumers).

Warning

The resource is meant to be created/updated during tenant operations for e.g. the ones created during tenant onboarding. As of now, the primary intention of this resource is to enhance the parameters of subscription callback during tenant onboarding. But the resources may be used for further scenarios in the future.

Any RBAC related updates needed to create/modify the resources for e.g. in a custom tenant operation needs to be handled by consumers and assigned to the relevant job via serviceAccountName config for that workload (job).

Note that all instances of this resources found for a given tenant will be cleaned up before any CAPTenantOperation is created.

Usage

1 - Prerequisites

Prepare the SAP BTP global account and provider subaccount

Create service instances and bindings

SAP Authorization and Trust Management Service

SAP Software-as-a-Service Provisioning service

SAP HANA Cloud

SAP Service Manager service

2 - Deploying a CAP Application

3 - Tenant Subscription

Tenant Provisioning

Warning

Tenant Deprovisioning

4 - Application Upgrade

5 - Version Monitoring

Integration with Prometheus

Configure CAPApplication

Configure CAPApplicationVersion

Deletion Rules (Variant 1) based on Metric Type

Prometheus Metrics Data

Deletion Rules (Variant 2) as PromQL expression

Scrape Configuration

Prerequisite

Use Case

Evaluating CAPApplicationVersions for cleanup

6 - Resources

6.1 - CAPApplication

6.2 - CAPApplicationVersion

Workloads with deploymentDefinition

Port configuration

Monitoring configuration

Workloads with jobDefinition

Sequencing tenant operations

Sequencing content jobs

Full Example

6.3 - CAPTenant

Warning

6.4 - CAPTenantOperation

Warning

6.5 - CAPTenantOutput

Warning

Configure `CAPApplication`

Configure `CAPApplicationVersion`

Evaluating `CAPApplicationVersions` for cleanup

Workloads with `deploymentDefinition`

Workloads with `jobDefinition`