Swarm Mode New

Dozzle supports Docker Swarm Mode starting from version 8. When using Swarm Mode, Dozzle will automatically discover services and custom groups. Dozzle does not use Swarm API internally as it is limited. Dozzle implements its own grouping using swarm labels. Additionally, Dozzle merges stats for containers in a group. This means that you can see logs and stats for all containers in a group in one view. But it does mean each host needs to be setup with Dozzle.

How does it work?

When deployed in Swarm Mode, Dozzle will create a secured mesh network between all the nodes in the swarm. This network is used to communicate between the different Dozzle instances. The mesh network is created using mTLS with a private TLS certificate. This means that all communication between the different Dozzle instances is encrypted and safe to deploy any where.

Dozzle supports Docker stacks, services and custom groups for joining logs together. com.docker.stack.namespace and com.docker.compose.project labels are used for grouping containers. For services, Dozzle uses the service name as the group name which is com.docker.swarm.service.name.

How to enable Swarm Mode?

To deploy on every node in the swarm, you can use mode: global. This will deploy Dozzle on every node in the swarm. Here is an example using Docker Stack:

services:
  dozzle:
    image: amir20/dozzle:latest
    environment:
      - DOZZLE_MODE=swarm
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    ports:
      - 8080:8080
    networks:
      - dozzle
    deploy:
      mode: global
networks:
  dozzle:
    driver: overlay

Note that the DOZZLE_MODE environment variable is set to swarm. This tells Dozzle to automatically discover other Dozzle instances in the swarm. The overlay network is used to create the mesh network between the different Dozzle instances.

NOTE

Due to implementation details, the name for the service must be exactly dozzle. This is because Dozzle uses the service name to discover other Dozzle instances in the swarm. In the future, it would make sense to query the Docker API for all services with the current container ID.

Setting up simple authentication in Swarm Mode

To setup simple authentication, you can use Docker secrets to store users.yml file. Here is an example using Docker Stack:

services:
  dozzle:
    image: amir20/dozzle:latest
    environment:
      - DOZZLE_LEVEL=debug
      - DOZZLE_MODE=swarm
      - DOZZLE_AUTH_PROVIDER=simple
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    secrets:
      - source: users
        target: /data/users.yml

    ports:
      - "8080:8080"
    networks:
      - dozzle
    deploy:
      mode: global

networks:
  dozzle:
    driver: overlay
secrets:
  users:
    file: users.yml

In this example, users.yml file is stored in a Docker secret. It is the same as the simple authentication example.