Woodu/eea.docker.haproxy

HAProxy Docker image with docker links and reload support

HAProxy Docker image

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

• Debian: Jessie
• HAProxy: 1.8
• Expose: 5000

Supported tags and respective Dockerfile links

• :latest Dockerfile - Debian: Jessie, HAProxy: 1.8

Stable and immutable tags

• :1.8-1.1 Dockerfile - HAProxy: 1.8 Release: 1.1

See older versions

Changes

• CHANGELOG.md

Base docker image

• hub.docker.com

Source code

• github.com

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
$ docker-compose 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:/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 /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.

• STATS_PORT The port to bind statistics to - default 1936
• STATS_AUTH The authentication details (written as user:password for the statistics page - default admin:admin
• FRONTEND_NAME The label of the frontend - default http-frontend
• FRONTEND_PORT The port to bind the frontend to - default 5000
• FRONTEND_MODE Frontend mode - default http
• PROXY_PROTOCOL_ENABLED The option to enable or disable accepting proxy protocol (true stands for enabled, false or anything else for disabled) - default false
• COOKIES_ENABLED The option to enable or disable cookie-based sessions (true stands for enabled, false or anything else for disabled) - default false
• BACKEND_NAME The label of the backend - default http-backend
• BACKENDS The list of server_ip:server_listening_port to be load-balanced by HAProxy, separated by space - by default it is not set
• BACKENDS_PORT Port to use when auto-discovering backends, or when BACKENDS are specified without port - by default 80
• BACKENDS_MODE Backends mode - default http
• BALANCE The algorithm used for load-balancing - default roundrobin
• SERVICE_NAMES An optional prefix for services to be included when discovering services separated by space. - by default it is not set
• LOGGING Override logging ip address:port - default is udp 127.0.0.1:514 inside container
• LOG_LEVEL Set haproxy log level, default is notice ( only send important events ). Can be: emerg,alert,crit,err,warning,notice,info,debug
• DNS_ENABLED DNS lookup provided BACKENDS. Use this option when your backends are resolved by an internal/external DNS service (e.g. Docker 1.11+, Rancher)
• DNS_TTL DNS lookup backends every DNS_TTL minutes. Default 1 minute.
• TIMEOUT_CONNECT the maximum time to wait for a connection attempt to a VPS to succeed. Default 5000 ms
• TIMEOUT_CLIENT timeouts apply when the client is expected to acknowledge or send data during the TCP process. Default 50000 ms
• TIMEOUT_SERVER timeouts apply when the server is expected to acknowledge or send data during the TCP process. Default 50000 ms
• HTTPCHK The HTTP method and uri used to check on the servers health - default HEAD /
• INTER parameter sets the interval between two consecutive health checks. If not specified, the default value is 2s
• FAST_INTER parameter sets the interval between two consecutive health checks when the server is any of the transition state (read above): UP - transitionally DOWN or DOWN - transitionally UP. If not set, then INTER is used.
• DOWN_INTER parameter sets the interval between two consecutive health checks when the server is in the DOWN state. If not set, then INTER is used.
• RISE number of consecutive valid health checks before considering the server as UP. Default value is 2
• FALL number of consecutive invalid health checks before considering the server as DOWN. Default value is 3

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)