Custom Container Service

The orchestrator enables custom containers to be deployed using a YAML file. A corresponding Service Specification must look like:

service_type: container
service_id: foo
placement:
    ...
spec:
  image: docker.io/library/foo:latest
  entrypoint: /usr/bin/foo
  uid: 1000
  gid: 1000
  args:
    - "--net=host"
    - "--cpus=2"
  ports:
    - 8080
    - 8443
  envs:
    - SECRET=mypassword
    - PORT=8080
    - PUID=1000
    - PGID=1000
  volume_mounts:
    CONFIG_DIR: /etc/foo
  bind_mounts:
    - ['type=bind', 'source=lib/modules', 'destination=/lib/modules', 'ro=true']
  dirs:
    - CONFIG_DIR
  files:
    CONFIG_DIR/foo.conf:
      - refresh=true
      - username=xyz
      - "port: 1234"

where the properties of a service specification are:

service_id
A unique name of the service.
image
The name of the Docker image.
uid
The UID to use when creating directories and files in the host system.
gid
The GID to use when creating directories and files in the host system.
entrypoint
Overwrite the default ENTRYPOINT of the image.
args
A list of additional Podman/Docker command line arguments.
ports
A list of TCP ports to open in the host firewall.
envs
A list of environment variables.
bind_mounts
When you use a bind mount, a file or directory on the host machine is mounted into the container. Relative source=… paths will be located below /var/lib/ceph/<cluster-fsid>/<daemon-name>.
volume_mounts
When you use a volume mount, a new directory is created within Docker’s storage directory on the host machine, and Docker manages that directory’s contents. Relative source paths will be located below /var/lib/ceph/<cluster-fsid>/<daemon-name>.
dirs
A list of directories that are created below /var/lib/ceph/<cluster-fsid>/<daemon-name>.
files
A dictionary, where the key is the relative path of the file and the value the file content. The content must be double quoted when using a string. Use ‘\n’ for line breaks in that case. Otherwise define multi-line content as list of strings. The given files will be created below the directory /var/lib/ceph/<cluster-fsid>/<daemon-name>. The absolute path of the directory where the file will be created must exist. Use the dirs property to create them if necessary.
init_containers
A list of “init container” definitions. An init container exists to run prepratory steps before the primary container starts. Init containers are optional. One or more container can be defined. Each definition can contain the following fields:
- image
  The name of the container image. If left unspecified, the init container will inherit the image value from the top level spec.
- entrypoint
  Customize the default entrypoint of the image.
- entrypoint_args
  Arguments that will be passed to the entrypoint. Behaves the same as the generic extra_entrypoint_args field.
- volume_mounts
  Same as the Custom Container spec’s volume_mounts - selects what volumes will be mounted into the init container. If left unspecified, the init container will inherit the primary container’s value(s).
- envs
  A list of environment variables.
- privileged
  A boolean indicate if the container should run with privileges or not. If left unspecified, the init container will inherit the primary container’s value.

Example with init containers:

service_type: container
service_id: foo
placement:
    ...
spec:
  image: quay.io/example/foosystem:latest
  entrypoint: /usr/bin/foo
  uid: 1000
  gid: 1000
  ports:
    - 8889
  dirs:
    - CONFIG_DIR
    - DATA_DIR
  volume_mounts:
    CONFIG_DIR: /etc/foo
    DATA_DIR: /var/lib/foo
  files:
    CONFIG_DIR/foo.conf:
      - db_path=/var/lib/foo/db
  init_containers:
    - image: quay.io/example/curly:howard
      entrypoint: bash
      entrypoint_args:
        - argument: "-c"
        - argument: "[ -f /var/lib/foo/db ] || curl -o /var/lib/foo/sample.dat https://foo.example.com/samples/1.dat"
      volume_mounts:
        DATA_DIR: /var/lib/foo
    - entrypoint: /usr/bin/foo-initialize-db
      entrypoint_args:
        - "--option=threads=8"
    - entrypoint: /usr/local/bin/import-sample-datasets.sh
      entrypoint_args:
        - "/var/lib/foo/sample.dat"
      envs:
        - FOO_SOURCE_MISSING=ignore
        - FOO_CLEANUP=yes

Note

Init containers are currently implemented as a step that runs before the service is started and is subject to start-up timeouts. The total run time of all init containers can not exceed 200 seconds or the service will fail to start.

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