[Bug]: Server fails silently when IPv6 is unavailable

[BirdRoad1]

Verified issue does not already exist?

• I have searched and found no existing issue

What happened?

When trying to start the server through docker or yarn (building from source), the program instantly exits after the following output:

actual@hostname:/opt/actual$ DEBUG=actual:config yarn start:server
  actual:config Project root: '/opt/actual/packages/sync-server' +0ms
  actual:config Actual web build path: '/opt/actual/packages/desktop-client/build' +1ms
  actual:config loading config from default path: '/opt/actual/packages/sync-server/config.json' +4ms
  actual:config Validating config +0ms
  actual:config Project root: /opt/actual/packages/sync-server +2ms
  actual:config Port: 5006 +0ms
  actual:config Hostname: :: +0ms
  actual:config Data directory: /opt/actual/packages/sync-server +0ms
  actual:config Server files: /opt/actual/packages/sync-server/server-files +0ms
  actual:config User files: /opt/actual/packages/sync-server/user-files +0ms
  actual:config Web root: /opt/actual/packages/desktop-client/build +0ms
  actual:config Login method: password +0ms
  actual:config Allowed methods: password, header, openid +0ms
Checking if there are any migrations to run for direction "up"...
Migrations: DONE
Running in production mode - Serving static React app
Listening on :::5006...

The exit code is 0.
Creating a config.json file with the following contents:
{ "hostname": "127.0.0.1" }
results in the server running as expected.

I would recommend falling back to IPv4 or having a descriptive error in case the server fails to bind to the host.

How can we reproduce the issue?

How can we reproduce the issue?

• Disable IPv6 using the "ipv6.disable=1" kernel parameter on Linux
• Run the server using yarn or docker
• The server exits immediately

Where are you hosting Actual?

Locally via Yarn

What browsers are you seeing the problem on?

Firefox

Operating System

Linux

[joel-jeremy]

Sync server uses express to spin up the server and it defaults to :: address when no hostname is configured. This is supposed to listen to both ipv6 and ipv4 accordingly, so if it's not doing so, it could be a bug on the express version that the sync server is using. I agree that an error message is desirable if connection failed, this could probably be achieved by updating the app.listen callback where we have access to an error object.