dock is a "micro init system" for linux containers

curl -sL https://github.com/robinmonjo/dock/releases/download/v0.1/dock-v0.1.tgz | tar -C /usr/local/bin -zxf -

This will place the latest dock binary in /usr/local/bin

• Yelp dumn-init
• Phusion baseimage docker

dock acts as the PID 1 in the container. It forwards every signals to it's child process. When a child process dies, dock :

1. detect one of its child died
2. send SIGTERM to all processes remaining in its process tree
3. call wait4 until no more children exist

Step 3 may block if some processes do not respond to the SIGTERM in step 2. If this is the case, a SIGKILL is sent after the SIGTERM (within a 5 seconds timeout)

dock is written in Go and has 0 dependency. The binary can simply be added into a linux container image. It also provides some useful features :

• can call a web hook when process state changes (starting, running and crashed)
• can say a process started only when a given port is bound (if you start a web server, you may want to know when this one is ready to accept connections), using this Go profcs package
• smart stdin / stdout (see the --io flag for more information)
• can provide log rotation (see --log-rotate flag for more information)

dock [OPTIONS] command

Allows to redirect process stdin / stdout:

• dock bash run bash with current stdin and stdout
• dock --io file:///var/run/process.log server.go redirect stdout to the given file. Stdin stay unchanged
• dock --io tcp://192.168.1.9:2567 bash make stdin and stdout go over a tcp connection
• dock --io tls://192.168.1.9:2657 bash make stdin and stdout go over a tls connection

Every URL scheme supported by Go's net.Dial are supported by dock

If specified, dock performs a HTTP PUT request with the JSON payload:

{
  "ps": {
    "status": "<status>"
  }
}

where <status> may be: starting, running or crashed. Note that if --bind-port flag is used, the running status is sent only once the given port is bound by one of dock children processes

Port dock's child process is expected to bind. Port may be bound by a descendant of dock (not only its direct child). This flag is useful only when the --web-hook flag is used.

If given --io is a file, specifying -log-rotate X perform a log rotation every X hours:

• archive (gzip) the current log file by prepending a timestamp (in the stdout file directory)
• empty the current log file
• keep at most 5 log archives

Add a prefix to stdout lines. Format: prefix[:<color>] where color may be white, green, blue, magenta, yellow, cyan or red

• use the Makefile and Dockerfile :)
• use the -d flag for verbosity
• the utils.go file contains some nice function to inspect and debug

• actually implement the kill timeout as it is documented :)
• check if err on start is a wait status and if so, return the exit code (i.e: 127 path not found)
• test port binding with nc and see why this ?
• fix log rotate test that fails regularly
• more tests !

• stdout prefix + coloring only available over network but sometimes prefix get written at the end of a line
• process is not stopped if interactive and over the network and the connection is closed