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eea / eea.docker.haproxy

HAProxy Docker image with docker links and reload support
https://registry.hub.docker.com/u/eeacms/haproxy/
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HAProxy Docker image

This image is generic, thus you can obviously re-use it within your non-related EEA projects.

Supported tags and respective Dockerfile links

Stable and immutable tags

See older versions

Changes

Base docker image

Source code

Installation

  1. Install Docker
  2. Install Docker Compose.

Usage

Run with Docker Compose

Here is a basic example of a docker-compose.yml file using the eeacms/haproxy docker image:

version: "2"
services:
  haproxy:
    image: eeacms/haproxy
    depends_on:
    - webapp
    ports:
    - "80:5000"
    - "1936:1936"
    environment:
      BACKENDS: "webapp"
      DNS_ENABLED: "true"
      LOG_LEVEL: "info"

  webapp:
    image: eeacms/hello

The application can be scaled to use more server instances, with docker-compose scale:

$ docker-compose up -d --scale webapp=4

The results can be checked in a browser, navigating to http://localhost. By refresing the page multiple times it is noticeable that the IP of the server that served the page changes, as HAProxy switches between them. The stats page can be accessed at http://localhost:1936 where you have to log in using the STATS_AUTH authentication details (default admin:admin).

Note that it may take up to one minute until backends are plugged-in due to the minimum possible DNS_TTL.

Run with backends specified as environment variable

$ docker run --env BACKENDS="192.168.1.5:80 192.168.1.6:80" eeacms/haproxy

Using the BACKENDS variable is a way to quick-start the container. The servers are written as server_ip:server_listening_port, separated by spaces (and enclosed in quotes, to avoid issues). The contents of the variable are evaluated in a python script that writes the HAProxy configuration file automatically.

If there are multiple DNS records for one or more of your BACKENDS (e.g. when deployed using rancher-compose), you can use DNS_ENABLED environment variable. This way, haproxy will load-balance all of your backends instead of only the first entry found:

$ docker run --link=webapp -e BACKENDS="webapp" -e DNS_ENABLED=true eeacms/haproxy

Use a custom configuration file mounted as a volume

$ docker run -v conf.d/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg eeacms/haproxy:latest

If you edit haproxy.cfg you can reload it without having to restart the container:

$ docker exec <name-of-your-container> reload

Extend the image with a custom haproxy.cfg file

Additionally, you can supply your own static haproxy.cfg file by extending the image

FROM eeacms/haproxy:latest
COPY conf.d/haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg

RUN apt-get install...

and then run

$ docker build -t your-image-name:your-image-tag path/to/Dockerfile

Supported environment variables

As HAProxy has close to no purpose by itself, this image should be used in combination with others (for example with Docker Compose).

HAProxy can be configured by modifying the following env variables, either when running the container or in a docker-compose.yml file.

Logging

By default the logs from haproxy are present in the docker log, by using the rsyslog inside the container (UDP port 514). No access logs are present by default, but this can be changed by setting the log level.

You can change the logging level by providing the LOG_LEVEL environment variable:

docker run -e LOG_LEVEL=info  ... eeacms/haproxy

You can override the log output by providing the LOGGING environment variable:

docker run -e LOGGING=logs.example.com:5005 ... eeacms/haproxy

Now make sure that logs.example.com listen on UDP port 5005

Copyright and license

The Initial Owner of the Original Code is European Environment Agency (EEA). All Rights Reserved.

The Original Code is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Funding

European Environment Agency (EU)