Create a service with a block storage volume mounted

Introduction

This tutorial provides step-by-step instructions for you to create a simple service that uses a block storage volume. You also take a snapshot of the storage volume and explore ways to use the snapshot.

Create a service

  1. Follow Tutorial 1 to download code for the sample service, create a Docker image, and upload it to a repository in your Snowflake account.

  2. Verify you have the my_echo_service_image image in the repository.

    SHOW IMAGES IN IMAGE REPOSITORY tutorial_db.data_schema.tutorial_repository;
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  3. Create a service. When the service runs, the container will have a 10 Gi block volume storage mounted.

    CREATE SERVICE my_service
 IN COMPUTE POOL tutorial_compute_pool
 FROM SPECIFICATION $$
spec:
  containers:
  - name: echo
    image: /tutorial_db/data_schema/tutorial_repository/my_echo_service_image:latest
    volumeMounts:
    - name: block-vol1
      mountPath: /opt/block/path
    readinessProbe:
      port: 8080
      path: /healthcheck
  endpoints:
  - name: echoendpoint
    port: 8080
    public: true
  volumes:
  - name: block-vol1
    source: block
    size: 10Gi
$$;
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    Note

    This tutorial only shows how to create a service with a block storage volume. The service code (Examining the tutorial 1 code) does not use the volume.

  4. To verify the service is running, execute the DESCRIBE SERVICE command.

    DESC SERVICE echo_service;
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    Verify the status column shows the service status as RUNNING; if the status is PENDING, it indicates the service is still starting. To investigate why the service is not RUNNING, execute the SHOW SERVICE CONTAINERS IN SERVICE command and review the status of individual containers:

    SHOW SERVICE CONTAINERS IN SERVICE echo_service;
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Take a snapshot

  1. Use the CREATE SNAPSHOT command to take a snapshot of the block storage volume attached to the service instance 0. You specify instance 0 because you are running only one service instance.

    Use double-quotes around the name in the VOLUME parameter to match the case of the name in the service specification.

    CREATE SNAPSHOT my_snapshot
  FROM SERVICE my_service
  VOLUME "block-vol1"
  INSTANCE 0
  COMMENT='new snapshot';
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  2. Review the snapshot

    • List snapshots using SHOW SNAPSHOTS.

      SHOW SNAPSHOTS;
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    • Retrieve information for a specific snapshot using DESCRIBE SNAPSHOT.

      DESC SNAPSHOT my_snapshot;
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  3. Run the ALTER SNAPSHOT command to modify the snapshot.

    ALTER SNAPSHOT my_snapshot SET comment='updated comment';
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Use the snapshot

  1. You can use the snapshot two ways:

    • Use snapshot to create a new service: When creating a new service, you can use the snapshot as the initial content for a block storage volume as shown. The following CREATE SERVICE command creates another service (new_service) with a 50 Gi block storage volume. The inline specification includes the snapshot name to use for initializing the block storage volume.

      CREATE SERVICE new_service
  IN COMPUTE POOL tutorial_compute_pool
  FROM SPECIFICATION $$
spec:
  containers:
  - name: echo
    image: /tutorial_db/data_schema/tutorial_repository/my_echo_service_image:tutorial
    volumeMounts:
    - name: fromsnapshotvol
      mountPath: /opt/block/path
    readinessProbe:
      port: 8080
      path: /healthcheck
  endpoints:
  - name: echoendpoint
    port: 8080
    public: true
  volumes:
  - name: fromsnapshotvol
    source: block
    size: 50Gi
    blockConfig:
      initialContents:
        fromSnapshot: MY_SNAPSHOT
$$
min_instances=3
max_instances=3;
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    • Restore a snapshot on a storage volume of an existing service: This example restarts the first service (my_service) you created by replacing the original block volume content with the content from the snapshot.

      1. Suspend the service so you can restore the snapshot on the block storage volume.

        ALTER SERVICE my_service SUSPEND;
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      2. Restore the snapshot on the block storage volume mounted on the container of the new_service instance. You are running only one instance of the Echo Service, so you specify instance ID 0.

        ALTER SERVICE my_service RESTORE     -- this will auto RESUME the service.
  VOLUME "block-vol1"
  INSTANCES 0
  FROM SNAPSHOT my_snapshot;
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      3. Verify the service status.

        DESC SERVICE echo_service;
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        The status column should show the service status as RUNNING;

  2. Use the DROP SNAPSHOT command to drop the snapshot.

    DROP SNAPSHOT my_snapshot;
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Clean up

Remove the resources you created.

  1. Drop the two services you created:

DROP SERVICE my_service;
DROP SERVICE new_service;
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  1. Follow Tutorial 1 steps to clean up other resources created in tutorial 1.

What’s next?

Now that you’ve completed this tutorial, you can return to Advanced tutorials to explore other topics.

Language: English