s3rj1k/ninit

ninit is a simple PID 1 init replacement for containers (k8s) that can also send reload signals on application config changes, can also be used as a library

ninit's Issues

Add INIT_RELOAD_SIGNAL_TO_PGID: true/false

Add INIT_RELOAD_SIGNAL_TO_PGID that controls how reload signals are sent.
To single process denoted by PID or to a process group denoted by process group ID (-PID).

https://unix.stackexchange.com/a/68759

"[…] When an argument of the form '-n' is given, and it is meant to denote a process group […]"

"[…] If pid is less than -1, then sig is sent to every process in the process group whose ID is -pid. […]"

"[…] If pid is negative, but not -1, sig shall be sent to all processes (excluding an unspecified set of system processes) whose process group ID is equal to the absolute value of pid, […]"

With default value of false: only send to specified PID

Add INIT_RELOAD_SIGNAL_TO_GPID: true/false

Add INIT_RELOAD_SIGNAL_TO_GPID that controls how reload signals are sent.
To single process denoted by PID or to a process group denoted by process group ID (-PID).

https://unix.stackexchange.com/a/68759

"[…] When an argument of the form '-n' is given, and it is meant to denote a process group […]"

"[…] If pid is less than -1, then sig is sent to every process in the process group whose ID is -pid. […]"

"[…] If pid is negative, but not -1, sig shall be sent to all processes (excluding an unspecified set of system processes) whose process group ID is equal to the absolute value of pid, […]"

Add logging of sent signals

https://github.com/s3rj1k/ninit/blob/main/main.go#L114

Consider adding `pause` chanel to temporary pause path pulling watch.

This can be used to pause changes watcher for a time when some external library is writing changes to disk.

Add ability to run external command before sending reload signal

Purpose of this is to validate child application config before reload, if config is invalid, log error, do not send reload signal.

Add ability to configure log level via environ.

Current log levels (from less verbose to most verbose):

• PanicLevelLog
• FatalLevelLog
• ErrorLevelLog
• WarnLevelLog
• InfoLevelLog
• DebugLevelLog
• TraceLevelLog

Add envar to optionaly disable signal forwarding to child process group.

Similar to:

• https://github.com/Yelp/dumb-init/blob/master/dumb-init.c#L66
• https://github.com/krallin/tini/blob/master/src/tini.c#L249

envar: INIT_SIGNAL_TO_DIRECT_CHILD_ONLY

In this mode, signals (excluding reload signal, configured separately) are only forwarded
to direct child and not to any of its descendants, meaning signal is sent to PID instead of PGID

Consider refactoring main.go to move more code into local packages

This should help with writing custom inits, for specific usage, like watching changed CR's in k8s and updating application config according to CR changes.

Fix typos in config help

https://github.com/s3rj1k/ninit/blob/main/pkg/config/config.go#L45

Consider adding ability to run subprocess on config change

Should be independent of signal send in terms of configuration.

Could be both signal and cmd or only one of them.

Also should be a none blocking exec.