docker-spotter

docker-spotter connects to a docker daemon, receives events and executes commands provided on the command line.

Usage

-addr="/var/run/docker.sock": address to connect to
-e=: Hook map with template text executed in docker event (see JSONMessage) context,
     format: container:event[,event]:command[:arg1:arg2...]
-proto="unix": protocol to use
-replay="": file to use to simulate/replay events from. Format = docker events
-since="1": watch for events since given value in seconds since epoch
-v=false: verbose logging

The command and each parameter get parsed as text/template and will get rendered with {{.Name}} set to the containers name, {{.ID}} to it's ID and {{.Event}} to the JSONMessage which triggered the event.

Available events:

• create
• start
• stop
• destroy

Example

This example will run pipework eth0 <id> 192.168.242.1/24 when a container named 'pxe-server' starts or restarts and echo gone when it stops.

./spotter \
  -e 'pxe-server:start,restart:pipework:eth0:{{.ID}}:192.168.242.1/24' \
  -e 'pxe-server:stop:echo:gone'

tcp proto and wildcards for containers

This example uses a tcp socket and specifies a wildcard to trigger the event on any container. The idea behind this is, to create a small program that assigns IP addresses depending on the container name.

./docker-spotter -addr=localhost:6000 -proto="tcp"
    -since=0
    -e '*:start:echo:{{.Name}}:up'
2014/07/01 10:30:36 = *:start:*:start:echo:{{.Name}}:up
2014/07/01 10:30:39 > /usr/bin/echo [ [/test up] ]
2014/07/01 10:30:39 - /test up

the environment variable (ENV) key/value pair as the event trigger for container matching.

This example will run pipework eth0 <id> 192.168.242.1/24 when a container has the FOO=BAR environment variable set.

./docker-spotter \
  -e 'FOO=BAR:start,restart:pipework:eth0:{{.ID}}:192.168.242.1/24' \
  -e 'FOO=BAR:stop:echo:gone'