[proposal] Allow graceful programmatic shutdown

[dryajov]

It's currently not possible to programmatically do a graceful shutdown of ipfs daemons on windows through the use of signals, the way it's done on Unix like systems - due to windows lack of signal support. From Node.js documentation - https://nodejs.org/api/process.html#process_signal_events.

This is an issue for applications that try to interact with the daemons programmatically such as ipfsd-ctl, since sending a SIGINT to any process will not trigger a signal handler, but simply kill the process, which in turn leaves the repo locked and possibly in an inconsistent state.

One possible solution would be to add some sort of explicit shutdown command (ipfsd shutdown) - that would shutdown the daemon. So far, I think this can be implemented either as an additional HTTP endpoint or by the presence of a 0 byte file at the root of the repo:

i.e.

• /api/v0/shutdown resource - when calling the endpoint, the daemon responds with a 200 or 202 HTTP response code and beggins the shutdown of the daemon
• .jsipfs/shutdown file - the daemon monitors the repo for the presence of this file, if its there, it will delete the file and initiate the daemon shutdown

This is just a suggestion, and if there are better/cleaner ways of achieving this, I'd love to hear about them.

Note that anything we do here, would also have to be done in the go implementation, since it affects both daemon types - // cc - @whyrusleeping @lgierth @Stebalien

[richardschneider]

@dryajov The docs already mention the shutdown endpoint.

IMHO, js-ipfs should implement it and then ipfsd-ctl can just call it, instead of using *nix signals.

[dryajov]

@richardschneider thanks for finding that, however I don't see this endpoint anywhere in js-ipfs, perhaps it is implemented in go only - in which case we should simply implement it in js.

[mkg20001]

Seems like on win10 SIGINT suddenly started to "just work" https://stackoverflow.com/a/45369603/3990041

[dryajov]

@mkg20001 hehe - yes, node correctly emulates SIGINT when using the cmd.

From the docs:

SIGINT from the terminal is supported on all platforms, and can usually be generated with <Ctrl>+C (though this may be configurable). It is not generated when terminal raw mode is enabled.

It's when using process.kill('SIGINT') that the signal emulation degrades to killing the process immediately.