Docker to Darcy

There are several possible docker run command line options that can be used when spinning up a Docker container. The following docker run commands can be directly mapped from a docker run command to a Darcy Cloud YAML configuration file:

  1. Volumes
  2. Environment Variables
  3. Ports
  4. Arguments / Commands
  5. Privilege

Volumes

Volumes are primarily used to share data between containers or nodes, or to persist data upon the destruction of containers or nodes

Docker Run Command

docker run <image> -v /path/to/mount/directory:/path/to/destination/in/container

Darcy Cloud YAML Configuration

container:
  # Microservice container volume mapping list on the agent
  volumes:
    # This will create a volume mapping between the agent '/tmp/msvc' volume
    # and the microservice container '/data' volume
    - hostDestination: /tmp/msvc
      containerDestination: /data
      # ReadWrite access to the mounted volume
      accessMode: 'rw'
      # Accepts 'bind' or 'volume'. Default is 'bind'
      type: 'bind'

Environment Variables

Environment variables for a Docker container can be set through the command line. We can list these same key-value pairs in the YAML configuration as shown below

Docker Run Command

docker run <image> ---env BASE_URL=http://localhost:8080/data

Darcy Cloud YAML Configuration

container:
  # Microservice container environment variable list on the agent
  env:
    # This will create an environment variable inside the microservice container
    # with the key 'BASE_URL' and the value 'http://localhost:8080/data'
    - key: BASE_URL
      value: http://localhost:8080/data

Ports

We use the -p flag to map the port number of a container to the port number of the Docker host via the Docker command line. It is equally simple to expose ports in an Darcy Cloud YAML configuration file

Docker Run Command

docker run <image> -p 5000:80

Darcy Cloud YAML Configuration

container:
  # Microservice container port mapping list on the agent
  ports:
    # This will create a mapping between the port 80 of the microservice
    # container and the port 5000 of the agent that runs over TCP
    - internal: 80
      external: 5000
      protocal: tcp

Arguments / Commands

Similar to Docker, we can run the same commands via Darcy Cloud YAML as we can via the command line with the exception of entrypoint arguments

Docker Run Command

docker run <image> dbhost localhost:27017

Darcy Cloud YAML Configuration

container:
  commands:
    - 'dbhost'
    - 'localhost:27017'

Privileged

The privileged command line argument tells the container whether or not it has access to the root of the node or machine it is being run on

Docker Run Command

docker run <image> --privileged

Darcy Cloud YAML Configuration

container:
  rootHostAccess: true