Usage

To run this docker container use the following command

docker run -d ashwanthkumar/gocd-agent:latest

Environment variables

In order to configure the agent for use in your cluster with other than default settings you can pass in the following environment variables

Name	Description	Default value
GO_SERVER	The host name or ip address of the server to connect to	localhost
GO_SERVER_PORT	The http port of the go server	8153
AGENT_MEM	The -Xms value for the java vm	128m
AGENT_MAX_MEM	The -Xmx value for the java vm	256m
AGENT_KEY	The secret key set on the server for auto-registration of the agent
AGENT_RESOURCES	The resource tags for the agent in case of auto-registration
AGENT_ENVIRONMENTS	The environments the agent is assigned to in case of auto-registration
AGENT_HOSTNAME	The hostname used for the agent; normally it's the hosts actual hostname
AGENT_GUID	GUID of the agent; normally it is left blank and auto-generated by the server
DOCKER_GID_ON_HOST	To mount docker socket and use it without sudo the go user needs to be added to the docker group; pass in the gid from the guest os with this variable

To connect the agent to your server with other than default ip or hostname

docker run -d \
    -e "GO_SERVER=gocd.yourdomain.com" \
    ashwanthkumar/gocd-agent:latest

If you've set up your server for autoregistration of agents pass in the same value for environment variable AGENT_KEY when starting the agent

docker run -d \
    -e "GO_SERVER=gocd.yourdomain.com" \
    -e "AGENT_KEY=388b633a88de126531afa41eff9aa69e" \
    ashwanthkumar/gocd-agent:latest

You can also set resource tags, gocd environment and hostname for the agent when autoregistering

docker run -d \
    -e "GO_SERVER=gocd.yourdomain.com" \
    -e "AGENT_KEY=388b633a88de126531afa41eff9aa69e" \
    -e "AGENT_RESOURCES=deploy-x,deploy-z" \
    -e "AGENT_ENVIRONMENTS=Production" \
    -e "AGENT_HOSTNAME=deploy-agent-01" \
    ashwanthkumar/gocd-agent:latest

To mount docker socket and be able to use it sudo-less inside the container use the following

docker run -d \
    -e "GO_SERVER=gocd.yourdomain.com" \
    -e "DOCKER_GID_ON_HOST=$(getent group docker | cut -d: -f3)" \
    -v /var/run/docker.sock:/var/run/docker.sock \
    -v /usr/bin/docker:/usr/bin/docker \
    ashwanthkumar/gocd-agent:latest

Do be aware that mounting docker inside your container poses a large security risk as the container indirectly has access to the whole machine in this way.

Mounting volumes

In order to keep working copies over a restart and use ssh keys from the host machine you can mount the following directories

Directory	Description	Importance
/var/lib/go-agent/pipelines	This directory holds the working copies for all pipelines that have run on this agent	You want to have this cleaned up regularly anyway, so no real need to mount it
/var/log/go-agent	All output logs go here, but there also written to standard out in the container	Preferably collect logs from standard out
/var/go/.ssh	The ssh keys to connect to version control systems like github and bitbucket	As it's better not to embed these keys in the container you likely need to mount this
/var/run/docker.sock	To mount the docker socket of the guest os	Note: mounting this is a security risk!
/usr/bin/docker	To mount the docker binary of the guest os	Note: mounting this is a security risk!

Start the container like this to mount the directories

docker run -d \
    -e "GO_SERVER=gocd.yourdomain.com" \
    -e "AGENT_KEY=388b633a88de126531afa41eff9aa69e" \
    -e "AGENT_RESOURCES=deploy-x,deploy-z" \
    -e "AGENT_ENVIRONMENTS=Production" \
    -e "AGENT_HOSTNAME=deploy-agent-01" \
    -v /mnt/persistent-disk/gocd-agent/pipelines:/var/lib/go-agent/pipelines
    -v /mnt/persistent-disk/gocd-agent/logs:/var/log/go-agent
    -v /mnt/persistent-disk/gocd-agent/ssh:/var/go/.ssh
    -v /var/run/docker.sock:/var/run/docker.sock \
    -v /usr/bin/docker:/usr/bin/docker \
    ashwanthkumar/gocd-agent:latest

To make sure the process in the container can read and write to those directories create a user and group with same gid and uid on the host machine

groupadd -r -g 999 go
useradd -r -g go -u 999 go

And then change the owner of the host directories

chown -R go:go /mnt/persistent-disk/gocd-agent/pipelines
chown -R go:go /mnt/persistent-disk/gocd-agent/ssh