59 lines
1.4 KiB
Markdown
59 lines
1.4 KiB
Markdown
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# reap
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If you have a Docker container that's a collection of runit-supervised daemons,
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this process is suitable for use as the ENTRYPOINT.
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```Docker
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FROM alpine:latest
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RUN echo "http://dl-4.alpinelinux.org/alpine/edge/testing" >>/etc/apk/repositories && apk add --update runit && rm -rf /var/cache/apk/*
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ADD foo /
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RUN mkdir -p /etc/service/foo
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ADD run-foo /etc/service/foo/run
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ADD bar /
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RUN mkdir -p /etc/service/bar
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ADD run-bar /etc/service/bar/run
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ADD reap /
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ENTRYPOINT ["/reap"]
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```
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**Why not just exec runsvdir?**
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`docker stop` issues SIGTERM (or, in a future version of Docker, perhaps another custom signal)
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but if runsvdir receives a signal,
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it doesn't wait for its supervised processes to exit before returning.
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If you don't care about graceful shutdown of your daemons, no problem, you don't need this tool.
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**Why not wrap runsvdir in a simple shell script?**
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This works great:
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```sh
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#!/bin/sh
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sv_stop() {
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for s in $(ls -d /etc/service/*)
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do
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/sbin/sv stop $s
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done
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}
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trap "sv_stop; exit" SIGTERM
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/sbin/runsvdir /etc/service &
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wait
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```
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...except it doesn't [reap orphaned child processes](https://blog.phusion.nl/2015/01/20/docker-and-the-pid-1-zombie-reaping-problem/)
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and is therefore unsuitable for being PID 1.
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**Why not use my_init from phusion/baseimage-docker?**
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That works great — if you're willing to add python3 to your Docker images :)
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**So this is just a stripped-down my_init in Go?**
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Basically, yes.
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