chore: manage mutagen daemon lifecycle #98

ethanndickson · 2025-03-07T03:36:04Z

Moves the VPN-specific app files into a VPN folder.
Adds an empty Resources folder whose contents are copied into the bundle at build time.
Adds a MutagenDaemon abstraction for managing the mutagen daemon lifecycle, this class:
- Starts the mutagen daemon using mutagen daemon run, with a MUTAGEN_DATA_DIRECTORY in Application Support/Coder Desktop/Mutagen, to avoid collisions with a system mutagen using ~/.mutagen.
- Maintains a gRPC connection to the daemon socket.
- Stops the mutagen daemon over gRPC
- Relays stdout & stderr from the daemon, and watches if the process exits unexpectedly.
- Handles replacing an orphaned mutagen daemon run process if one exists.

This PR does not embed the mutagen binaries within the bundle, it just handles the case where they're present.

Why is the file sync code in VPNLib?

When I had the FileSync code (namely protobuf definitions) in either:

The app target
A new FSLib framework target

Either the network extension crashed (in the first case) or the app crashed (in the second case) on launch.
The crash was super obtuse:

Library not loaded: @rpath/SwiftProtobuf.framework/Versions/A/SwiftProtobuf

especially considering SwiftProtobuf doesn't have a stable ABI and shouldn't be compiled as a framework.

At least one other person has ran into this issue when importing SwiftProtobuf multiple times:
apple/swift-protobuf#1506 (comment)

Curiously, this also wasn't happening on local development builds (building and running via the XCode GUI), only when exporting via our build script.

Solution

We're just going to overload VPNLib as the source of all our SwiftProtobuf & GRPC code. Since it's pretty big, and we don't want to embed it twice, we'll embed it once within the System Extension, and then have the app look for it in that bundle, see LD_RUNPATH_SEARCH_PATHS. It's not exactly ideal, but I don't think it's worth going to war with XCode over.

TODO

Replace the Process with https://github.com/jamf/Subprocess

ethanndickson · 2025-03-07T03:36:20Z

chore: add mutagen gRPC client #111
refactor: replace spaces with hyphens in directory names #110
ci: download mutagen binary into resources #103
chore: manage mutagen daemon lifecycle #98 👈 (View in Graphite)
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ethanndickson · 2025-03-07T03:51:59Z

Coder Desktop/Coder Desktop/State.swift

@@ -4,6 +4,7 @@ import KeychainAccess
 import NetworkExtension
 import SwiftUI

+@MainActor


drive-by fix: I believe this is implicit in the ObservableObject conformance, but can't hurt to make it explicit.

Coder Desktop/Resources/.gitkeep

ethanndickson · 2025-03-07T03:54:32Z

Coder Desktop/Coder Desktop/FileSync/FileSyncDaemon.swift

+}
+
+@MainActor
+class MutagenDaemon: FileSyncDaemon {


Open to suggestions on how to test this. We can easily mock the gRPC calls, but mocking the child process is ???.

I've just done a good amount of manual testing for now.

ethanndickson · 2025-03-07T03:56:16Z

Coder Desktop/Coder Desktop/FileSync/FileSyncDaemon.swift

+        // Stop an orphaned daemon, if there is one
+        try? await connect()
+        try? await stop()


For context, mutagen daemon run acquires a file lock in the MUTAGEN_DATA_DIRECTORY. Multiple instances of the daemon will fail to start, so we need to make sure one isn't running before we start ours. If, for whatever reason, we were unable to kill the daemon, the new one will immediately fail and change the DaemonState.

ThomasK33

The PR looks good on the surface, I'll have to test it locally later and look for edge cases.

Makefile

flake.nix

ThomasK33 · 2025-03-07T11:40:52Z

Coder Desktop/Coder Desktop/FileSync/daemon.proto

@@ -0,0 +1,11 @@
+syntax = "proto3";


QQ: Haven't seen a discussion before, but have we considered using the edition2023 version instead of proto3?

Coder Desktop/Coder Desktop/FileSync/FileSyncDaemon.swift

Makefile

ThomasK33

LGTM. I think there's an issue in the Coder_DesktopApp.swift file with quitting the VPN on quit

Coder Desktop/VPNLib/FileSync/FileSyncDaemon.swift

Coder Desktop/Coder Desktop/Coder_DesktopApp.swift

ThomasK33

LGTM

ethanndickson · 2025-03-12T05:43:04Z

Merge activity

Mar 12, 1:43 AM EDT: A user started a stack merge that includes this pull request via Graphite.
Mar 12, 1:43 AM EDT: A user merged this pull request with Graphite.

This makes a few improvements to #98: - The mutagen path & data directory can be now be configured on the MutagenDaemon, to support overriding it in tests (coming soon). - A mutagen daemon failure now kills the process, such that can it be restarted (TBC). - Makes start & stop transitions mutually exclusive via a semaphore, to account for actor re-entrancy. - The start operation now waits for the daemon to respond to a version request before completing. - The daemon is always started on launch, but then immediately stopped if it doesn't manage any file sync sessions, as to not run in the background unncessarily.

ethanndickson force-pushed the ethan/mutagen-lifecycle branch from 6f638fd to e9fa904 Compare March 7, 2025 03:46

ethanndickson commented Mar 7, 2025

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ethanndickson marked this pull request as ready for review March 7, 2025 04:06

ethanndickson requested review from deansheather and ThomasK33 March 7, 2025 04:16

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ethanndickson force-pushed the ethan/mutagen-lifecycle branch from a013cde to 3384471 Compare March 10, 2025 01:37

ethanndickson mentioned this pull request Mar 10, 2025

ci: download mutagen binary into resources #103

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ethanndickson force-pushed the ethan/mutagen-lifecycle branch from 3384471 to 7f92c54 Compare March 10, 2025 03:02

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ethanndickson requested review from ThomasK33 and spikecurtis and removed request for deansheather March 11, 2025 05:28

ThomasK33 approved these changes Mar 11, 2025

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ethanndickson added 13 commits March 12, 2025 13:29

chore: manage mutagen daemon lifecycle

0f362f8

handle missing mutagen

513ccd8

fixup

3291e73

gitkeep resources

9be6173

fixup

b0cbab8

only import swiftprotobuf in vpnlib to debug runtime crash

ebcadbe

extract to seperate lib

5ed3893

move back to vpnlib

c1947aa

remove duplicate framework

b13a44f

logging

c9cba6d

review

2b673b8

error handling

76abed5

log privacy

f2fc365

ethanndickson added 5 commits March 12, 2025 13:29

fixup

21bb169

fixup

2bf41aa

process -> subprocess package

16a7263

use async let

382fd9b

fixup

ad1b24d

ethanndickson force-pushed the ethan/mutagen-lifecycle branch from 1d0a6e1 to ad1b24d Compare March 12, 2025 02:30

ethanndickson mentioned this pull request Mar 12, 2025

refactor: replace spaces with hyphens in directory names #110

Merged

ethanndickson merged commit 6f6049e into main Mar 12, 2025
4 checks passed

ethanndickson deleted the ethan/mutagen-lifecycle branch March 12, 2025 05:43

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chore: add mutagen gRPC client #111

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chore: conditionally start file sync daemon #115

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chore: manage mutagen daemon lifecycle #98

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chore: manage mutagen daemon lifecycle #98

chore: manage mutagen daemon lifecycle #98

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ethanndickson commented Mar 7, 2025 • edited Loading

Why is the file sync code in VPNLib?

Solution

TODO

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