TrivialRC
The minimalistic init system and process manager for usage primarily in containers.
From here and further, by a container I mean Docker.
TrivialRC is not a replacement for an init process that usually exists in /sbin/init and has a PID 1. In containers for this purpose are being used projects like dumb-init or tini.
This is an equivalent to a common, for xBSD, /etc/rc. Init system that is used for managing startup and shutdown process. It can start and stop one or more processes, in parallel or sequentially, on back- or foreground. All commands can be specified in the command line if they are simple, or in a separate file, if more comprehensive scenario is needed.
TrivialRC is designed to be used as an Entrypoint. By default, it does not show itself, does not affect any configuration and behaves transparently. So, you can add it into any containers which do not have an entrypoint. Please, have a look at examples for more information.
Anyway, to be sure that all processes will be stopped on exit and all zombies are properly reaped, at least for now, it is highly recommended to use inside containers some init process like one of mentioned above.
Installation
Basically, you need the only one file (trc) that can be downloaded directly from GitHub, but as long as it likely is going to be used in containers...
- You need to add into your Dockerfile something like
RUN curl -sSLo /etc/trc https://raw.githubusercontent.com/vorakl/TrivialRC/master/trc && \
chmod +x /etc/trcIf you are going to use it in pair with init, for example dumb-init
RUN curl -sSLo /sbin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v1.0.1/dumb-init_1.0.1_amd64 && \
chmod +x /sbin/dumb-init- If you need to change a behavior of rc system, set appropriate variables like
ENV RC_VERBOSE true
ENV RC_WAIT_POLICY wait_all- If you have additional files, add them all at once
COPY trc* /etc/- Eventually, if you do not use init process, specify only rc system
ENTRYPOINT ["/etc/trc"]Otherwise, which is RECOMMENDED, add an init process and rc system together, for example
ENTRYPOINT ["/sbin/dumb-init", "/etc/trc"]