docker: add pidFilePath to avoid waking a socket-activated daemon - #2176
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toby-bro wants to merge 1 commit into
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docker: add pidFilePath to avoid waking a socket-activated daemon#2176toby-bro wants to merge 1 commit into
toby-bro wants to merge 1 commit into
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I noticed that
wtfwould start my Docker daemon again within seconds of stopping it, keeping dockerd running (and burning CPU).The cause is systemd socket activation (
dockerd -H fd://) : systemd owns the listening socket and starts the daemon on the first connection, so polling the Docker API to find out whether the daemon is up starts it.This PR adds a check that will read the dockerd's pid file, whose default location is documented as
/var/run/docker.pidinstead of querying the socket.pkg/pidfile.Readalso verifies the process is alive, so a stale file from a crashed daemon doesn't produce a false positive.It is opt-in : with
pidFilePathunset, the module behaves exactly as before.If the installation is "standardish" then the
pidFilePath: "auto"should manage to detect the actual location of the file.Otherwise it can be manually specified.
It could reasonably become the default, but a wrong path reads as "daemon not running", and setups like Docker Desktop or a custom --pidfile have no file where we'd look so I didn't want to break anyone's wtf silently.
Unit tests for the new file were written with Claude.