keepalived_containers

Repository for building keepalived container images.

Quick Start

This image requires the kernel module ip_vs loaded on the host (modprobe ip_vs) and needs to run with :

• --cap-add=NET_ADMIN
• --net=host

docker run --cap-add=NET_ADMIN --net=host -d ednxzu/keepalived:latest

Versions

All images are available on Dockerhub.

This repository builds all keepalived version >2.0.0, with a few exeptions. Some versions have undocumented build dependencies, and since I have not found how to build them, they are skipped for now.

Included versions:

• 2.2.3
• 2.2.4
• 2.2.7
• 2.2.8
• 2.3.0
• 2.3.1
• 2.3.2

Excluded versions:

• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.5 (not an actual release)
• 2.2.6

If you know how any of these versions can be built, please feel free to submit a PR to add them to the build list.

Specific version tags X.Y.Z, as well as X.Y, X and latest are available and automatically updated on rebuild.

New images are automatically built every 15 days, in order to keep the base image up-to-date. New keepalived versions are automatically fetched from the keepalived repository, and will be built either by me manually triggering a new build, or during the next scheduled build (every 15 days).

Since images are rebuilt from upstream alpine images, and compiled from source every time, I cannot guarantee immutability of the images (it is dependent on upstream alpine), but realistically, you should be fine treating them as immutable images 🙂

Setup

Simple Setup

This image is made to be super easy to customize without having to rebuild it or do any gymnastic.

The following environment variables are available by default.

Name	Description	Required	Default
CONFIG	Path to the config file (keepalived.conf)	No	/etc/keepalived/keepalived.conf
VRRP_INSTANCE	Name of the VRRP Instance of the container	No	$HOSTNAME
INTERFACE	The interface to attach the virtual IP to	No	eth0
UNICAST_SRC_IP	The source IP for unicast	No	ip of $INTERFACE
UNICAST_PEERS	Comma-separated list of peers	No	NOT SET
STATE	Initial state of the keepalived instance	No	BACKUP
ROUTER_ID	Unique identifier for the router	No	50
PRIORITY	Priority of the VRRP instance	No	100
ADVERTISE_INTERVAL	Advertisement interval in seconds	No	1
VIRTUAL_IPS	Virtual IP addresses and associated interfaces	No	192.168.2.100/32 dev $INTERFACE
PASSWORD	Authentication password for VRRP communication	No	password
NOTIFY	Path to the script to be executed on state transitions	No	/notify.sh

These variables are used to configure keepalived instance, but in simple scenarios, most of them can be left untouched.

An example config to deploy a simple virtual IP would look like:

docker run --cap-add=NET_ADMIN \
--net=host \
-e INTERFACE=ens1 \
-e VIRTUAL_IPS="10.1.20.10" \
ednxzu/keepalived

Bring your own template

This image uses a package called envsubst to render a working configuration file from a "template"

The initial configuration template looks like this:

[...]
vrrp_instance ${VRRP_INSTANCE} {
  interface ${INTERFACE}

  state ${STATE}
  virtual_router_id ${ROUTER_ID}
  priority ${PRIORITY}
  advert_int ${ADVERTISE_INTERVAL}
[...]

The entrypoint will simply look for and replace environment variables found within the template, which means that you can make your own template and use your own environment variables within it to render the exact configuration you need.

docker run --cap-add=NET_ADMIN \
--net=host \
-v "./keepalived.conf:/etc/keepalived/keepalived.conf"
-e INTERFACE=ens1 \
-e VIRTUAL_IPS="10.1.20.10" \
-e YOUR_VARIABLE=1337 \
ednxzu/keepalived

Bring your own config

In the event that the entrypoint does not find any occurence of ${*} within the file specified in $CONFIG, it will assume that the configuration does not need templating, and will simply try to run it as is.

This means that you can also bring your own configuration altogether, and forget about the environment variables.

docker run --cap-add=NET_ADMIN \
--net=host \
-v "./keepalived:/etc/keepalived"
ednxzu/keepalived

This way, you can add features that are not built-in to this image, like check scripts, etc...