Implementing Blue-Green Deployment with SAP BTP, Cloud Foundry Runtime for Zero Downtime Updates

1. Ensure you have all the prerequisites installed and configured.

   1. Perform the required steps.

2. Clone the SAP CAP Book Shop Application.

   1. Enter the following code:

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      git clone https://github.tools.sap/SAP-BTP-Courses/cf400_sample_app bookshop
      
      cd bookshop

3. Install Dependencies.

   1. Enter the following code:

      npm install

4. Log in to Cloud Foundry.

   1. Enter the following code:

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      cf api <API-ENDPOINT>
      cf login
      cf target -o <ORG> -s <SPACE>

      You can find the API endpoint in the Overview section of your subaccount in the SAP BTP cockpit.

1. Build the application for production.

   1. Enter the following code:

      cds build --production

      The --production parameter ensures that the cloud deployment-related artifacts are created by cds build.

2. Generate the Initial MTA Archive for the Application.

   1. Enter the following code:

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      mbt build  -t gen --mtar hello-cloud-foundry-blue.mta
      
      INFO generating the MTA archive...
      INFO the MTA archive generated at: gen\hello-cloud-foundry-blue.mta

      You can find the API endpoint in the Overview section of your subaccount in the SAP BTP cockpit.

3. Deploy the initial environment (blue) using the existing .mta file.

   1. Enter the following code:

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      cf deploy  .\gen\hello-cloud-foundry-blue.mta -f --strategy blue-green
      ...
      Operation ID: 1b313fd2-7a96-11ef-910c-eeee0a9ee328
      ...
      No deployed MTA detected - this is initial deployment
      ...
      Starting application "hello-cloud-foundry-srv-idle"...
      Application "hello-cloud-foundry-srv-idle" started and available at "<org>-<space>-hello-cloud-foundry-srv-idle.<domain>"
      ...
      Renaming application "hello-cloud-foundry-srv-idle" to "hello-cloud-foundry-srv"...
      ...

      Note for Mac Users: The command provided uses a Windows-specific file path format (for example, .\mta_archives\hello-cloud-foundry-blue.mtar). On a Mac, you'll need to modify the path format to Unix-style by replacing the backslashes (\) with forward slashes ('/'). For example, use ./mta_archives/hello-cloud-foundry-blue.mtar instead.

4. Check if the apps are running.

   1. Enter the following code:

      cf apps

5. Enter the route displayed for hello-cloud-foundry-srv in your browser to see the CAP start page.

   

6. Choose $metadata to explore the book entity's fields.

   

1. Modify the Entity Definition.

   1. Open the db/data-model.cds file where the Book entity is defined. It might look something like this:

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      namespace my.bookshop;
      
      entity Books {
      key ID : Integer;
      title  : String;
      stock  : Integer;
      }

   2. Add the new publishedDate field to the Books entity:

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      namespace my.bookshop;
      
      entity Books {
      key ID : Integer;
      title  : String;
      stock  : Integer;
      publishedDate : Date; // New required field
      }

2. Build and Deploy the Green Environment (new version).

   1. Build the multitarget application archive.

      mbt build -t gen --mtar hello-cloud-foundry-green.mta

   2. Deploy the Green Environment (new version).

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      cf deploy  .\gen\hello-cloud-foundry-green.mta -f --strategy blue-green
      
      ...
      Operation ID: 34099f67-7a9b-11ef-90ea-eeee0a9a9d78
      ...
      Renaming application "hello-cloud-foundry-srv" to "hello-cloud-foundry-srv-live"...
      ...
      Starting application "hello-cloud-foundry-srv-idle"...
      Application "hello-cloud-foundry-srv-idle" started and available at "<org>-<space>-hello-cloud-foundry-srv-idle.<domain>"
      ...
      Process has entered testing phase. After testing your new deployment you can resume or abort the process.
      Use "cf deploy -i 34099f67-7a9b-11ef-90ea-eeee0a9a9d78 -a abort" to abort the process.
      Use "cf deploy -i 34099f67-7a9b-11ef-90ea-eeee0a9a9d78 -a resume" to resume the process.
      Hint: Use the "--skip-testing-phase" option of the deploy command to skip this phase.   Hint: Use the '--skip-testing-phase' option of the deploy command to skip this phase.
      ...

1. Test the Green Application(Idle).

   1. Check if the apps are running:

      cf apps

   2. Ensure the application hello-cloud-foundry-srv-idle is functioning correctly with the new 'publishedDate' field.

      

In this task, you'll transition the GREEN environment to become the new productive environment by switching routes and verifying the deployment.

1. Make the GREEN environment the productive one.

   1. Get the Operation ID.

      cf mta-ops

   2. Make the GREEN environment the active production environment. Use the following code:

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      cf deploy -i 34099f67-7a9b-11ef-90ea-eeee0a9a9d78 -a resume
      
      Executing action "resume" on operation 34099f67-7a9b-11ef-90ea-eeee0a9a9d78...
      ...
      Updating application "hello-cloud-foundry-srv-idle"...
      Stopping application "hello-cloud-foundry-srv-idle"...
      Starting application "hello-cloud-foundry-srv-idle"...
      Application "hello-cloud-foundry-srv-idle" started and available at "<org>-<space>-hello-cl2bbcd228.<domain>"
      Renaming application "hello-cloud-foundry-srv-idle" to "hello-cloud-foundry-srv"...
      Deleting routes for application "hello-cloud-foundry-srv-live"...
      Stopping application "hello-cloud-foundry-srv-live"...
      Deleting application "hello-cloud-foundry-srv-live"...
      Process finished.

2. Examine the result.

   1. Verify that the old BLUE applications are deleted and the new GREEN applications are assigned to productive routes.

      cf apps

   2. Verify that the GREEN environment is the productive one and serves on the productive routes, enter the route displayed for hello-cloud-foundry-srv in your browser, and check the book entity's fields.

      

It's recommended to stop or undeploy your MTAs when they are no longer needed. In order to do so, run the following command.

1. Clean up resources

   1. Use the following code:

      cf undeploy hello-cloud-foundry --delete-services --delete-service-keys -f