Using Docker

Hermes uses a multi stage docker build for hermetic builds, while creating a minimal image. Hence, please ensure you use Docker v17.05 or newer.

git clone https://github.com/c16a/hermes.git
cd hermes
docker build -t hermes-app .

Running the image

docker run -p 4000:4000 -v $pwd/config.json:/app/config.json hermes-app

The above example assumes that the TCP server has been configured to listen on port 4000. In case that is configured to another port, please configure the docker exposed port accordingly.

SELinux policies

When using Docker on a host with SELinux enabled, the container is denied access to certain parts of host file system unless it is run in privileged mode. To resolve this, you can use a named volume

# Create a docker volume and map it to /tmp/hermes on the host
docker volume create --driver local --opt type=none --opt device=/tmp/hermes --opt o=bind hermes_volume

# Ensure /tmp/hermes/config.json has the required broker configuration
# Use the above created hermes_volume to mount the config file into the container
docker run -p 4000:4000 -e CONFIG_FILE_PATH=/tmp/hermes/config.json --mount source=hermes_volume,target=/tmp/hermes hermes

Please note that however, you place your config.json in the /tmp directory, SELinux does not restrict you access when you use a direct volume mapping.

# This won't work with SELinux enabled
docker run -p 4000:4000 -e CONFIG_FILE_PATH=/tmp/hermes/config.json -v /home/user/config.json:/tmp/hermes/config.json hermes

# This will work
docker run -p 4000:4000 -e CONFIG_FILE_PATH=/tmp/hermes/config.json -v /tmp/hermes/config.json:/tmp/hermes/config.json hermes

The Configuration section has more details on which attributes of the broker can be configured.

Running in Compose mode

Create the named volume hermes_volume.

# Create a docker volume and map it to /tmp/hermes on the host
docker volume create --driver local --opt type=none --opt device=/tmp/hermes --opt o=bind hermes_volume

Reference the named volume for the service

version: "3.9"
services:
  broker:
    build:
      context: .
    environment:
      CONFIG_FILE_PATH: "/tmp/hermes/config.json"
    volumes:
      - hermes_volume:/tmp/hermes
    ports:
      - 4000:4000
      - 5000:5000
volumes:
  hermes_volume:
    external: true