can't mount composer home directory from host

[jacksontong]

I'm running docker on mac and I got this error when trying to mount the composer home directory from the host to the container

docker run --rm -it -v $COMPOSER_HOME:/composer composer bash
docker: Error response from daemon: invalid volume spec ":/composer": invalid volume specification: ':/composer'.
See 'docker run --help'.

docker version:

Client:
 Version:      17.03.0-ce
 API version:  1.26
 Go version:   go1.7.5
 Git commit:   60ccb22
 Built:        Thu Feb 23 10:40:59 2017
 OS/Arch:      darwin/amd64

Server:
 Version:      17.03.0-ce
 API version:  1.26 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   3a232c8
 Built:        Tue Feb 28 07:52:04 2017
 OS/Arch:      linux/amd64
 Experimental: true

[jacksontong]

When I replaced $COMPOSER_HOME by the real path (/Users/toantv/.composer:/composer) it works.

[alcohol]

$COMPOSER_HOME is not an environment variable that exists by default. You have to manually populate it. You can run env on your localhost to see what environment variables exist.