procfile

Overview ¶

Package procfile provides a parser that know how read an extended version of Procfile as described by Heroku (https://devcenter.heroku.com/articles/procfile).

This version allows to set specific behaviors per process type.

Example:

workdir: $GOPATH/src/github.com/example/go-app
observe: *.go *.js
ignore: /vendor
formation: web=2
build-server: make server
web: restart=fail waitfor=localhost:8888 ./server serve

Special process type names:

- workdir: the working directory. Environment variables are expanded. It follows the same rules for exec.Command.Dir.

- observe: a space separated list of file patterns to scan for. It uses filepath.Match internally. File patterns preceded with exclamation mark (!) will not trigger builds.

- ignore: a space separated list of ignored directories relative to workdir, typically vendor directories.

- formation: allows to start more than one instance for a given process type. if the process type is declared with zero ("proc=0"), it is not started. Non declared process types are started once. Each process type has its own exclusive $PORT variable value.

- waitfor (in process type): target hostname and port that the runner will probe before starting the process type.

- restart (in process type): "always" will restart the process type at every build; "fail" will restart the process type on failure; "loop" restart the process when it naturally terminates.

- group (in process type): group of processes that depend on each other. If a process type fails, it will halt all others in the same group. If the "restart" parameter is not set to "always" or "fail", the affected process types will halt and not restart.

- sticky (in build process types): a sticky build is not interrupted when file changes are detected.

- optional (in process types): does not start this process unless explicit told so.

Although internally runner.Runner supports waitbefore and multi-command processes, for simplicity of interface these features have been disabled in Procfile parser.