traefik-kop

A dynamic docker->redis->traefik discovery agent.

Solves the problem of running a non-Swarm/Kubernetes multi-host cluster with a single public-facing traefik instance.

                        +---------------------+          +---------------------+
                        |                     |          |                     |
+---------+     :443    |  +---------+        |   :8088  |  +------------+     |
|   WAN   |--------------->| traefik |<-------------------->| svc-nginx  |     |
+---------+             |  +---------+        |          |  +------------+     |
                        |       |             |          |                     |
                        |  +---------+        |          |  +-------------+    |
                        |  |  redis  |<-------------------->| traefik-kop |    |
                        |  +---------+        |          |  +-------------+    |
                        |             docker1 |          |             docker2 |
                        +---------------------+          +---------------------+

traefik-kop solves this problem by using the same traefik docker-provider logic. It reads the container labels from the local docker node and publishes them to a given redis instance. Simply configure your traefik node with a redis provider and point it to the same instance, as in the diagram above.

Usage

Configure traefik to use the redis provider, for example via traefik.yml:

providers:
  providersThrottleDuration: 2s
  docker:
    watch: true
    endpoint: unix:///var/run/docker.sock
    swarmModeRefreshSeconds: 15s
    exposedByDefault: false
  redis:
    endpoints:
      # assumes a redis link with this service name running on the same
      # docker host as traefik
      - "redis:6379"

Run traefik-kop on your other nodes via docker-compose:

version: "3"
services:
  traefik-kop:
    image: "ghcr.io/jittering/traefik-kop:latest"
    restart: unless-stopped
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      - "REDIS_ADDR=192.168.1.50:6379"
      - "BIND_IP=192.168.1.75"

Then add the usual labels to your target service:

services:
  nginx:
    image: "nginx:alpine"
    restart: unless-stopped
    ports:
      # The host port binding will automatically be picked up for use as the
      # service endpoint. See 'service port binding' in the configuration
      # section for more.
      - 8088:80
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.nginx.rule=Host(`nginx-on-docker2.example.com`)"
      - "traefik.http.routers.nginx.tls=true"
      - "traefik.http.routers.nginx.tls.certresolver=default"
      # [opptional] explicitly set the port binding for this service.
      # See 'service port binding' in the configuration section for more.
      - "traefik.http.services.nginx.loadbalancer.server.scheme=http"
      - "traefik.http.services.nginx.loadbalancer.server.port=8088"

See also bind-ip section below.

Configuration

traefik-kop can be configured via either CLI flags are environment variables.

USAGE:
   traefik-kop [global options] command [command options] [arguments...]

GLOBAL OPTIONS:
   --hostname value       Hostname to identify this node in redis (default: "server.local") [$KOP_HOSTNAME]
   --bind-ip value        IP address to bind services to (default: "auto.detected.ip.addr") [$BIND_IP]
   --redis-addr value     Redis address (default: "127.0.0.1:6379") [$REDIS_ADDR]
   --redis-pass value     Redis password (if needed) [$REDIS_PASS]
   --redis-db value       Redis DB number (default: 0) [$REDIS_DB]
   --docker-host value    Docker endpoint (default: "unix:///var/run/docker.sock") [$DOCKER_HOST]
   --docker-config value  Docker provider config (file must end in .yaml) [$DOCKER_CONFIG]
   --poll-interval value  Poll interval for refreshing container list (default: 60) [$KOP_POLL_INTERVAL]
   --verbose              Enable debug logging (default: true) [$VERBOSE, $DEBUG]
   --help, -h             show help (default: false)
   --version, -V          Print the version (default: false)

Most important are the bind-ip and redis-addr flags.

IP Binding

There are a number of ways to set the IP published to traefik. Below is the order of precedence (highest first) and detailed descriptions of each setting.

1. kop.<service name>.bind.ip label
2. kop.bind.ip label
3. Container networking IP
4. --bind-ip CLI flag
5. BIND_IP env var
6. Auto-detected host IP

bind-ip

Since your upstream docker nodes are external to your primary traefik server, traefik needs to connect to these services via the server's public IP rather than the usual method of using the internal docker-network IPs (by default 172.20.0.x or similar).

When using host networking this can be auto-detected, however it is advisable in the majority of cases to manually set this to the desired IP address. This can be done using the docker image by exporting the BIND_IP environment variable.

traefik-kop service labels

The bind IP can be set via label for each service/container.

Labels can be one of two keys:

• kop.<service name>.bind.ip=2.2.2.2
• kop.bind.ip=2.2.2.2

For a container with a single exposed service, or where all services use the same IP, the latter is sufficient.

Container Networking

If your container is configured to use a network-routable IP address via an overlay network or CNI plugin, that address will override the bind-ip configuration above when the traefik.docker.network label is present on the service.

Service port binding

By default, the service port will be picked up from the container port bindings if only a single port is bound. For example:

services:
  nginx:
    image: "nginx:alpine"
    restart: unless-stopped
    ports:
      - 8088:80

8088 would automatically be used as the service endpoint's port in traefik. If you have more than one port or are using host networking, you will need to explicitly set the port binding via service label, like so:

services:
  nginx:
    image: "nginx:alpine"
    network_mode: host
    ports:
      - 8088:80
      - 8888:81
    labels:
      # (note: other labels snipped for brevity)
      - "traefik.http.services.nginx.loadbalancer.server.port=8088"

NOTE: unlike the standard traefik-docker usage, we need to expose the service port on the host and tell traefik to bind to that port (8088 in the example above) in the load balancer config, not the internal port (80). This is so that traefik can reach it over the network.

Docker API

traefik-kop expects to connect to the Docker host API via a unix socket, by default at /var/run/docker.sock. The location can be overridden via the DOCKER_HOST env var or --docker-host flag.

Other connection methods (like ssh, http/s) are not supported.

By default, traefik-kop will listen for push events via the Docker API in order to detect configuration changes. In some circumstances, a change may not be pushed correctly. For example, when using healthchecks in certain configurations, the start -> healthy change may not be detected via push event. As a failsafe, there is an additional polling mechanism to detect those missed changes.

The default interval of 60 seconds should be light so as not to cause any issues, however it can be adjusted as needed via the KOP_POLL_INTERVAL env var or set to 0 to disable it completely.

Traefik Docker Provider Config

In addition to the simple --docker-host setting above, all Docker Provider configuration options are available via the --docker-config <filename.yaml> flag which expects either a filename to read configuration from or an inline YAML document.

For example:

services:
  traefik-kop:
    image: "ghcr.io/jittering/traefik-kop:latest"
    restart: unless-stopped
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      REDIS_ADDR: "172.28.183.97:6380"
      BIND_IP: "172.28.183.97"
      DOCKER_CONFIG: |
        ---
        docker:
          defaultRule: Host(`{{.Name}}.foo.example.com`)

Releasing

To release a new version, simply push a new tag to github.

git push
git tag -a v0.11.0
git push --tags

To update the changelog:

make update-changelog
# or (replace tag below)
docker run -it --rm -v "$(pwd)":/usr/local/src/your-app \
  githubchangeloggenerator/github-changelog-generator \
  -u jittering -p traefik-kop --output "" \
  --since-tag v0.10.1

License

traefik-kop: MIT, (c) 2022, Pixelcop Research, Inc.

traefik: MIT, (c) 2016-2020 Containous SAS; 2020-2022 Traefik Labs