Error when start watching folder containing resolv.conf

[lstocchi]

#450 added a watcher to start watching the directory containing the resolv.conf file to be up to date of the name servers defined in it.

However it may fails at setting the watcher and resulting in gvproxy to not starting as it should.

On MacOS, I have the symlink /etc/resolv.conf -> /private/var/run/resolv.conf. When, inside ../var/run, there is the symlink docker.sock -> /Users/luca/.local/share/containers/podman/machine/podman.sock I face a gvproxy exiting: cannot add network services: adding watcher failed: "/private/var/run/docker.sock": no such file or directory. If the symlink is removed, everything works as expected.

[cfergeau]

Does /Users/luca/.local/share/containers/podman/machine/podman.sock exist?
https://github.com/fsnotify/fsnotify/blob/a9bc2e01792f868516acf80817f7d7d7b3315409/backend_kqueue.go#L392-L397 has some code to ignore non existent symlinks, dunno why it does not trigger here

[cfergeau]

@fatanugraha for what it's worth, there are still some issues after your file watch changes :(

[lstocchi]

@cfergeau yes it exists

[fatanugraha]

Ouch, let me reproduce and see if i can think of any quick fix for this.

[fatanugraha]

By adding the code below into the test

	_, err := net.Listen("unix", filepath.Join(dir, "lol.sock"))
	if err != nil {
		panic(err)
	}
	panic(dir)

	os.Symlink(filepath.Join(dir, "non-existent"), filepath.Join(dir, "hehe2"))
	os.Symlink(filepath.Join(dir, "lol.sock"), filepath.Join(dir, "hehe"))

I'm not able to reproduce the exact error but I got this error when i created a symlink to a socket.

        	Error Trace:	/Users/fatanugraha/fun/gvisor-tap-vsock/pkg/utils/filewatcher_test.go:45
        	Error:      	Received unexpected error:
        	            	adding watcher failed: "/Users/fatanugraha/Desktop/hehe": operation not supported on socket

after a quick skim into fsnotify code, it doesn't seem to have any check on the destination file after resolving the link and they don't expose any useful options that we can use to workaround this error :/

If fsnotify/fsnotify#661 is resolved we can add the watch to /etc (rather than /private/var/run) which can be also a good workaround.