Dockerfile: How to replace a placeholder in environment variable with build-arg's?
Variable expansion can only work in double-quoted strings. This is working:
ENV CONFIG "{ \ \"credentials\":{ \ \"hostname\": \"172.17.0.5\", \ \"password\": \"PWD\", \ \"port\": \"1234\", \ \"username\": \"${USER}\" \ }, \ \"name\":\"database\", \ \"tags\":[] \ }"A simple example:
FROM alpineENV USER fooENV CONFIG "{ \ \"credentials\":{ \ \"hostname\": \"172.17.0.5\", \ \"password\": \"PWD\", \ \"port\": \"1234\", \ \"username\": \"${USER}\" \ }, \ \"name\":\"database\", \ \"tags\":[] \ }"ENTRYPOINT env | sort_
$ docker build -t test .$ docker run -it --rm testCONFIG={ "credentials":{ "hostname": "172.17.0.5", "password": "PWD", "port": "1234", "username": "foo" }, "name":"database", "tags":[] }HOME=/rootHOSTNAME=43d29bd12bc5PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/binPWD=/SHLVL=1TERM=xtermUSER=foo