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    Hybrid Testing

    Introduction

    You can easily test your CAP application using a local database and mock ups. But at some point, you’re going to want to test with real cloud services. Of course, you can always deploy your application to the cloud.

    With hybrid testing capabilities, you can stay in your local development environment and avoid the long turnaround times of cloud deployment, and you can selectively decide which services you want to use from the cloud.

    Use the cds bind command to connect your application to services on the cloud. Start your application with the hybrid profile to use these service bindings. You can switch between local mock configuration and cloud service configuration by simply setting or omitting the profile parameter.

    Bind to Cloud Services

    Bind a Local Application to Services on Cloud Foundry

    cds bind -2 my-hana:my-hana-key
    

    Binds your CAP application to the my-hana-key service key for the my-hana service instance, using your currently targeted Cloud Foundry space.

    Output:

    [bind] - Retrieving data from Cloud Foundry...
    [bind] - Binding db to Cloud Foundry service cpapp-db key cpapp-db-key with kind hana.
    [bind] - Saving bindings to .cdsrc-private.json in profile hybrid .
    [bind] -
    [bind] - TIP: Run with cloud bindings: cds watch --profile hybrid
    

    The service key needs to be created beforehand.

    You can omit :my-hana-key here, because the key name is just the name of the instance with -key added.

    In many cases, CAP knows which CDS service and kind to use for a cloud service. Like in the previous example, the db CDS service gets bound and set to the hana kind, because the given service instance is of type hana with plan hdi-shared.

    Learn how to bind to arbitrary cloud services.

    The binding information is stored in the .cdsrc-private.json file of your project in the requires section:

    {
      "requires": {
        "[hybrid]": {
          "db": {
            "kind": "hana",
            "binding": {
              "type": "cf",
              "apiEndpoint": "https://api.sap.hana.ondemand.com",
              "org": "your-cf-org",
              "space": "your-cf-space",
              "instance": "my-hana",
              "key": "my-hana-key",
              "vcap": {
                "label": "hana",
                "plan": "hdi-shared"
              },
              "resolved": false
            }
          }
        }
      }
    }
    

    Bindings are assigned to the hybrid profile by default.

    Note that no credentials are saved. Only the information about where the credentials can be obtained is stored on your machine.

    All cds bind command line options

    Bind a Local Application to Services on Kubernetes

    You can bind to Service Bindings of Open Service Broker service instances, such as SAP BTP services, on your Kubernetes cluster and to plain Kubernetes Secrets by adding the --on k8s option to the cds bind command:

    cds bind -2 <service binding or secret> --on k8s
    

    The command uses your current Kubernetes context. That is your current server and namespace. You need to be logged in as a precondition.

    Bind to Kubernetes Service Bindings

    To list all Service Bindings in your current Kubernetes context, you can use the kubectl get servicebindings command:

    NAME                  SERVICE-INSTANCE      SECRET-NAME           STATUS   AGE
    cpapp-xsuaa-binding   cpapp-xsuaa           cpapp-xsuaa-secret    Ready    11s
    

    Use the service binding name for the -2 option:

    cds bind -2 cpapp-xsuaa-binding --on k8s
    

    Output:

    [bind] - Retrieving data from Kubernetes...
    [bind] - Binding uaa to Kubernetes service binding cpapp-xsuaa-binding with kind xsuaa
    [bind] - Saving bindings to .cdsrc-private.json in profile hybrid
    [bind] -
    [bind] - TIP: Run with cloud bindings: cds watch --profile hybrid
    

    The binding information is stored in the .cdsrc-private.json file of your project in the requires section:

    {
      "requires": {
        "[hybrid]": {
          "uaa": {
            "binding": {
              "type": "k8s",
              "name": "cpapp-xsuaa-binding",
              "cluster": "https://apiserver.d9a6204.kyma-stage.shoot.live.k8s-hana.ondemand.com",
              "instance": "cpapp-xsuaa",
              "namespace": "dev",
              "secret": "cpapp-xsuaa-secret",
              "resolved": false,
              "vcap": {
                "label": "xsuaa",
                "plan": "application"
              }
            },
            "kind": "xsuaa"
          }
        }
      }
    }
    

    Bind to Kubernetes Secrets

    Alternatively, you can bind to Kubernetes Secrets.

    You can use the kubectl get secrets command to list all secrets in your current Kubernetes context:

    NAME                                    TYPE                                  DATA   AGE
    cap-hdi-container                       Opaque                                11     44h
    

    Use the secret name for the -2 option.

    You need to provide either the service argument or the --kind option as well, because secrets have no service metadata.

    cds bind -2 cap-hdi-container --on k8s --kind hana
    

    Output:

    [bind] - Retrieving data from Kubernetes...
    [bind] - Binding db to Kubernetes secret cap-hdi-container with kind hana
    [bind] - Saving bindings to .cdsrc-private.json in profile hybrid
    [bind] -
    [bind] - TIP: Run with cloud bindings: cds watch --profile hybrid
    

    If a service binding with the same name exists, cds bind will connect to the service binding instead.

    Run with Service Bindings

    Run CAP Node.js Apps with Service Bindings

    Now, you can run your CAP service locally using the cloud service bindings:

    cds watch --profile hybrid
    

    It will resolve the cloud bindings in your configuration:

    1. Bindings to Cloud Foundry: The credentials are downloaded from the service key of the Cloud Foundry API endpoint, org, and space that were targeted when cds bind was being called. This requires you to be logged in to the correct Cloud Foundry API endpoint.
    2. Bindings to Kubernetes: The credentials are downloaded from the service bindings and secrets of the Kubernetes cluster and namespace that were in the current context when cds bind was being called.

    You can also resolve and display credentials using the cds env command:

    cds env get requires.db.credentials --profile hybrid --resolve-bindings
    

    Example output:

    {
      url: 'jdbc:sap://BDB9AC0F20CB46B494E6742047C4F99A.hana.eu10.hanacloud.ondemand.com:443?encrypt=true&validateCertificate=true&currentschema=BDB9AC0F20CB46B494E6742047C4F99A',
      host: 'bdb9ac0f20cb46b494e6742047c4f99a.hana.eu10.hanacloud.ondemand.com',
      port: '443',
      driver: 'com.sap.db.jdbc.Driver',
      schema: 'BDB9AC0F20CB46B494E6742047C4F99A',
      hdi_user: 'BDB9AC0F20CB46B494E6742047C4F99A_DT',
      hdi_password: 'abc...xyz',
      user: 'BDB9AC0F20CB46B494E6742047C4F99A_RT',
      password: 'abc....xyz',
      certificate: '-----BEGIN CERTIFICATE-----\n' +
        '...' +
        '-----END CERTIFICATE-----'
    }
    

    Only cds watch and cds env (the latter with the --resolve-bindings option) resolve cloud bindings. Bindings are resolved by cds serve or cds exec.

    Run Arbitrary Commands with Service Bindings

    With cds bind you avoid storing credentials on your hard disk. If you need to start other applications with cloud service bindings from local, then you can use the exec sub command of cds bind.

    For example, you can run the approuter from the approuter child directory:

    cds bind --exec -- npm start --prefix approuter
    
    cds bind --exec -- npm start --prefix approuter
    
    cds bind --exec '--' npm start --prefix approuter
    

    This works by building up a VCAP_SERVICES variable from the bindings in the chosen profiles (default: hybrid). You can run the following command to print the content of the generated VCAP_SERVICES variable:

    cds bind --exec -- node -e 'console.log(process.env.VCAP_SERVICES)'
    
    cds bind --exec -- node -e 'console.log(process.env.VCAP_SERVICES)'
    
    cds bind --exec '--' node -e 'console.log(process.env.VCAP_SERVICES)'
    

    Run CAP Java Apps with Service Bindings

    Start your CAP Java application with the cds bind --exec command to use the service bindings.

    For example:

    cds bind --exec mvn spring-boot:run
    

    Run with Service Bindings from a Running Cloud Application

    Run CAP Apps Using Cloud Application Bindings

    Instead of binding to specific cloud services, you can run your application with all service bindings of an application on the SAP BTP, Cloud Foundry environment.

    But you need to have (1) your application deployed, and (2) be logged in to your Cloud Foundry space using the cf command line.

    For example, you can use the following syntax with bash or similar shells:

    VCAP_SERVICES=$(cf env <CF-APP-NAME> | perl -0pe '/VCAP_SERVICES:(.*?)VCAP_APPLICATION:/smg; $_=$1') cds watch --profile hybrid
    

    Your profile should have the kind settings to use the bound services, for example requires.db = hana.

    cds bind Usage

    By Cloud Service Only

    The shortest way to use cds bind is to specify only the Cloud Foundry service instance name:

    cds bind -2 my-hana
    

    This implies that a service key exists with the suffix -key. In this example: my-hana-key.

    You can specify a different key after a colon (“:”):

    cds bind -2 my-hana:my-different-key
    

    With CDS Service and Kind

    If kind or CDS service cannot be determined automatically by cds bind, you need to specify it:

    cds bind credstore -2 my-credstore --kind credstore
    

    You are informed with an error message if this is required.

    Bind Multiple Services with One Command

    There is a handy shortcut to bind multiple services with one command:

    cds bind -2 my-hana,my-destination,my-xsuaa
    

    This shortcut is only possible if you don’t need to provide a service or a kind.

    With Profile and Output File

    By default, the bindings for the hybrid profile are stored in the .cdsrc-private.json file in your current working directory.

    This can be overwritten using the --profile and --output-file options.

    Execute Commands with Bindings

    You can start arbitrary command line programs with your bindings.

    The service bindings are resolved from the cloud and provided in the VCAP_SERVICES env variable to the application. So it works with every application that can consume Cloud Foundry credentials.

    cds bind --exec [--] <command> <args ...>
    

    Use the double-dash (--) if your command has args starting with a dash (-) character. Otherwise the cds command line will try to parse them as their own options.

    On PowerShell you need to quote the double dash (--) when an option with double dash follows, e.g.

    cds bind --exec '--' somecmd --someflag --some-double-dash-parameter 42
    

    Profiles can be set using the optional --profile parameter. By default the hybrid profile is used.

    cds bind --exec --profile <profile> [--] <command> <args ...>
    

    The --profile parameter must follow exec directly.

    Use Cases

    Most of the following use cases are shown for Node.js, but can be easily adapted for Java.

    Destinations

    Learn how to connect to remote services from local using SAP BTP destinations.

    Authentication and Authorization using XSUAA

    Learn how to do hybrid testing using the XSUAA service in the CAP Node.js authentication documentation.

    Integration Tests

    cds bind can be handy for testing with real cloud services in your CI/CD pipeline.

    Configure your required bindings for testing and save them to your project’s package.json file for your tests’ profile:

    cds bind -2 integration-test-hana -o package.json -p integration-test
    

    No credentials are saved!

    In your CI/CD pipeline you can resolve the bindings and inject them into the test commands:

    # Install DK for "cds env"
    npm i @sap/cds-dk --no-save
    
    # Login
    cf auth $USER $PASSWORD
    
    ## Uncomment if your service bindings have
    ## no "org" and "space" set (see note below)
    # cf target -o $ORG -s $SPACE
    
    # Set profile
    export CDS_ENV=integration-test
    # Set resolved bindings
    export cds_requires="$(cds env get requires --resolve-bindings)"
    
    # Execute test
    npm run integration-test
    

    With CDS_ENV, you specify the configuration profile for the test, where you previously put the service binding configuration.

    cds env get requires prints the requires section of the configuration as a JSON string. By adding the --resolve-bindings option, it includes the credentials of the service bindings from the cloud. To make the credentials available for all subsequent cds commands and the tests, the requires JSON string is put into the cds_requires variable.

    Service bindings created by cds bind contain the Cloud Foundry API endpoint, org, and space. You can allow your services to connect to the currently targeted Cloud Foundry org and space by removing these properties from the binding structure.