entrypoint-args

Entrypoint args & passthrough

With gopherd as the image ENTRYPOINT, what happens to docker run arguments depends on their shape:

Invocation	Result
docker run image	normal init, no extra args
docker run image --debug	daemon mode; --debug appended to the use-entrypoint-args service
docker run image -- --debug	same — -- explicitly separates entrypoint args
docker run image /bin/sh	passthrough: execs /bin/sh directly, no init
docker run image status	client mode (known command)

Arguments starting with - go to the service; a bare command that isn't a known client command replaces gopherd via exec — handy for debugging containers (docker run image ls -la /etc).

Config

processes:
  - name: app
    command: /bin/sh
    args: ["-c", "echo $* > ARGSFILE; exec sleep 300", "app"]
    use-entrypoint-args: true
    on-failure: shutdown

• At most one service may set use-entrypoint-args: true (config error otherwise); entrypoint args are appended after its configured args.
• With no consuming service, passed entrypoint args are discarded with a warning.

Expected behavior

• gopherd --port 9090 starts the daemon and app sees --port 9090 as extra arguments.
• gopherd /bin/echo hello prints hello and exits — gopherd is replaced by the command, nothing is supervised.

Test

Run level. One test launches the daemon with entrypoint args and asserts the service received them appended. The other invokes the binary with a bare command and asserts passthrough exec output. SIGTERM yields a clean exit 0.

go test ./documentation/entrypoint-args/ -v