wait is a really small Docker utility that blocks until another container is accepting TCP connections, and errors-out if it cannot connect within a given timeout. I use this
in CI environments to ensure that server containers are up before tests begin running
against them.
The default operation looks up all the EXPOSEd ports of all the linked containers
and waits for them
$ docker run -d --name mycontainer some-image-or-other
$ docker run --link mycontainer:mycontainer waisbrot/wait
waiting for 172.17.0.105:5432 . up!
Everything is upIt doesn't matter what the link alias is.
If you want to wait for only a subset of the links/ports, or you want to connect
to hosts/ports that haven't been linked by Docker, you can provide the list in
the TARGETS variable:
$ docker run -e TARGETS=8.8.8.8:53,github.com:443 waisbrot/wait
waiting for 8.8.8.8:53 . up!
waiting for github.com:443 . up!
Everything is upBy default each connection attempt will bail after 30 seconds. You can specify an override using the TIMEOUT env variable:
$ docker run -e TARGETS=github.com:5432 waisbrot/wait
waiting for github.com:5432 ............................... ERROR: unable to connectIf any TARGET times out, the wait container immediately exits with status code 1
credits
The single port usage idea and dockerfile was pulled from aanand/wait: https://github.com/aanand/docker-wait