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Container Solution

Configuring data output from a Docker container to a serial port

To create a VM from an image such as a Container Optimized Image and set up a redirect of the application output stream to the VM's serial port:

  1. Prepare your cloud.
  2. Create a VM specification file.
  3. Create a Docker container specification file.
  4. Get the ID of the image to create the VM.
  5. Create a VM.
  6. Check the results.

If you no longer need the resources you created, delete them.

Prepare your cloud

If the required Docker image is pushed to Container Registry, create a service account with the container-registry.images.puller role for the registry in use. A Container Optimized Image VM will pull the Docker image from the registry on behalf of this account.

If you don't have the Nebius Israel command line interface yet, install and initialize it.

The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

If you don't have a network or subnet, create them.

The infrastructure support cost includes:

Create a VM specification file

Create a VM specification file named cloud-config-ports.yaml and populate it with the following data:

#cloud-config
runcmd:
  - [ sudo, chmod, 666, /dev/ttyS1]
users:
  - name: <username>
    groups: sudo
    shell: /bin/bash
    sudo: 'ALL=(ALL) NOPASSWD:ALL'
    ssh-authorized-keys:
      - <public SSH key to connect to VM>

In the file configuration, set the username and specify the public part of the SSH key required to connect to the VM. You need to create a key pair for SSH connection yourself.

Create a Docker container specification file

Create a specification for a Docker container as a file named container-spec-ports.yaml and populate it with the following data:

spec:
  containers:
  - image: ubuntu
    name: app
    command: ["/bin/bash", "-c", "sleep 30 && echo 'Hello World!' > /dev/ttyS1"]
    securityContext:
      privileged: true
    stdin: false
    tty: false
    volumeMounts:
      - mountPath: /dev/ttyS1
        name: log-port
  restartPolicy: Always
  volumes:
    - name: log-port
      hostPath:
        path: /dev/ttyS1
  1. Create a VM with multiple disks.

    1. Get the ID of the image to create the VM:

      • Bash

        IMAGE_ID=$(yc compute image get-latest-from-family container-optimized-image --folder-id standard-images --format=json | jq -r .id)

      • PowerShell

        > $IMAGE_ID=(yc compute image get-latest-from-family container-optimized-image --folder-id standard-images --format=json | ConvertFrom-Json).id

    2. Create a VM:

      yc compute instance create \
  --name coi-vm-with-sp \
  --zone il1-a \
  --network-interface subnet-name=<subnet name>,nat-ip-version=ipv4 \
  --metadata-from-file user-data=cloud-config-ports.yaml,docker-container-declaration=container-spec-ports.yaml \
  --create-boot-disk image-id=$IMAGE_ID

      Where:

      • --name: VM name.
      • --zone: availability zone.
      • --network-interface: VM network settings.
      • --metadata-from-file: YAML metadata files to create the VM.
      • --create-boot-disk: ID of the image to create a boot disk from.

      Once created, the VM appears in the VM list under Compute Cloud in the management console.

    3. Check the results.

      1. In the management console, go to the folder page and select Compute Cloud.
      2. Click on the name of the coi-vm-with-sp VM.
      3. Under Serial port, select COM2. In a few minutes, the screen displays Hello world!.

Get the ID of the image to create the VM

To get the ID of the latest image used for VM creation, run:

IMAGE_ID=$(yc compute image get-latest-from-family container-optimized-image \
  --folder-id standard-images \
  --format=json | jq -r .id)

$IMAGE_ID=(yc compute image get-latest-from-family container-optimized-image `
  --folder-id standard-images `
  --format=json | ConvertFrom-Json).id

Create a VM

Enter a name for the subnet to create your VM in and run:

yc compute instance create \
  --name coi-vm-with-sp \
  --zone il1-c \
  --network-interface subnet-name=<subnet name>,nat-ip-version=ipv4 \
  --metadata-from-file user-data=cloud-config-ports.yaml,docker-container-declaration=container-spec-ports.yaml \
  --create-boot-disk image-id=$IMAGE_ID

Where:

  • --name: VM name.
  • --zone: Availability zone.
  • --network-interface: VM network settings.
  • --metadata-from-file: YAML metadata files to create the VM.
  • --create-boot-disk: ID of the image to create a boot disk from.

Once created, the VM appears in the VM list under Compute Cloud in the management console.

Check the results

To check the result of configuring data output from the Docker container to the serial port:

  1. In the management console, go to the folder page and select Compute Cloud.
  2. Click the name of the coi-vm-with-sp VM.
  3. Under Serial port, select COM2. In a few minutes, the screen displays Hello world!.

For more information about working with VMs, see our step-by-step guides.

How to delete created resources

To stop paying for the resources you created:

  1. Delete the VM.
  2. If you reserved a public static IP address for the VM, delete it.
© 2023 Nebius Israel Ltd
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