HAProxy, Backend, ZEO container example

HAProxy, Backend, ZEO container example#

This example is a very simple setup with one or more backend instances accessing a ZEO server and data being persisted in a Docker volume.

HAProxy is used for load balancing in this example. We will use the image plone/plone-haproxy.

Setup#

Create a directory for your project, and inside it create a docker-compose.yml file that starts your Plone instance and the ZEO instance with volume mounts for data persistence.

services:

  lb:
    image: plone/plone-haproxy
    depends_on:
    - backend
    ports:
    - "8080:8080"
    - "1936:1936"
    environment:
      FRONTEND_PORT: "8080"
      BACKENDS: "backend"
      BACKENDS_PORT: "8080"
      DNS_ENABLED: "True"
      HTTPCHK: "GET /"
      INTER: "5s"
      LOG_LEVEL: "info"

  backend:
    image: plone/plone-backend:${STACK_BACKEND_TAG:?Set STACK_BACKEND_TAG}
    restart: always
    environment:
      ZEO_ADDRESS: zeo:8100
    ports:
    - "8080"
    depends_on:
      - zeo

  zeo:
    image: plone/plone-zeo:${STACK_ZEO_TAG:?Set STACK_ZEO_TAG}
    restart: always
    volumes:
      - vol-site-data:/data

volumes:
  vol-site-data: {}

Environment variables#

The docker-compose.yml file reads the tags of its images from the following environment variables. All of them are required, and docker compose stops with an error if one of them is missing.

Variable

Description

Default value

Example

STACK_BACKEND_TAG

Tag (version) of the image for the backend

6.2

STACK_ZEO_TAG

Tag (version) of the image for the ZEO server

6

Create a .env file in your project directory with your values. Docker Compose reads it automatically when you run docker compose from that directory.

STACK_BACKEND_TAG=6.2
STACK_ZEO_TAG=6

Build the project with multiple backends#

Run docker compose up -d --scale backend=4 from your project directory.

Access Plone via Browser#

Point your browser at http://localhost:8080. Login using the username and password combination of admin and admin. You should see the default Plone site creation page.

Access HAProxy Stats Page via Browser#

Point your browser at http://localhost:1936. Login using the username and password combination of admin and admin. You should see HAProxy statistics for your Plone cluster.

Shutdown and cleanup#

The command docker compose down removes the containers and default network, but preserves the Plone database.

The command docker compose down --volumes removes the containers, default network, and the Plone database.

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