Docker hacks and 1 liners I find useful

Docker Hacklets

Docker 1.12 Classic Mode

Number of nodes in cluster

 docker info | grep 12376 | wc -l

Find all cluster nodes with a specific label

 docker info | grep -B 6 <key>=<value> | grep 12376 | cut -d: -f1
 ex: docker info | grep -B 6 com.foobar.docker.env=demo | grep 12376 | cut -d: -f1

Send a Signal to a named container (or several based on --filter granularity)

 docker kill --signal "HUP" `docker ps --filter "name=<name>" --format "{{.ID}}"`
 ex:  docker kill --signal "HUP" `docker ps --filter "name=${PROJECT}_prometheus" --format "{{.ID}}"`
 
Remove <none> images

 docker images -q --filter "dangling=true" | xargs sudo docker rmi
  
Remove all exited containers

 docker rm $(docker ps -q -f status=exited)
 
Remove containers by specifying part of container name

 docker ps --filter "name=<part of name>" --format "{{.ID}}" | xargs docker kill
 ex: docker ps --filter "name=project_" --format "{{.ID}}" | xargs docker kill
 
Return an interesting subset of data about a container

 docker inspect --format ' Created: {{.Created}}{{"\n"}} Started: {{.State.StartedAt}}{{"\n"}} NodeIP: {{.Node.IP}}{{"\n"}} Networks:{{range $p, $conf := .NetworkSettings.Networks}} {{$p}}{{end}}{{"\n"}} CIPS:{{range .NetworkSettings.Networks}} {{.IPAddress}}{{end}}' $f_container
 
Return the list of containers in an overlay network

 docker network inspect --format '{{range .Containers}}{{.Name}} {{end}}' $f_network