Configuring data output from a Docker container to a serial port

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_for_connecting_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 an SSH key pair yourself.

Create the 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

      PowerShell

      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
      

   2. Create a VM:

      yc compute instance create \
        --name coi-vm-with-sp \
        --zone ru-central1-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 for creating the VM.

        Note

        The commands yc compute instance create | create-with-container | update | add-metadata support substitution of environment variable values into VM metadata. When you execute a Yandex Cloud CLI command, these values, specified in the user-data key in $<variable_name> format, will be substituted into the VM metadata from the environment variables of the environment the command is executed in.

        To change such behavior, i.e. to provide a variable name to the VM metadata in $<variable_name> format rather than take the variable value from the CLI command runtime environment, use the two-dollar syntax, e.g., $$<variable_name>.

        For more information, see Specifics of providing environment variables in metadata via the CLI.

      • --create-boot-disk: ID of the image to create a boot disk from.

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

   3. Check the result.

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

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

yc compute instance create \
  --name coi-vm-with-sp \
  --zone ru-central1-d \
  --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 for creating the VM.
• --create-boot-disk: ID of the image to create a boot disk from.