Add SYNCV3_SERVER_PUB environment variable pointing to the public homeserver URL

[spantaleev]

SYNCV3_SERVER continues to be used for connecting to the server.

SYNCV3_SERVER_PUB is a new environment variable (defaulting to the value of SYNCV3_SERVER), so that people who are already pointing SYNCV3_SERVER to a public URL do not need to set both.

This change affects the server field in the generated /client/server.json file, so that this field points to the public homeserver URL (SYNCV3_SERVER_PUB).

Related to spantaleev/matrix-docker-ansible-deploy#2583

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[spantaleev]

I'm not sure if this is the right place to fix this.

This is to benefit Element-web, which seems to be hitting /client/server.json and complaining that the internal homeserver URL there does not match the homeserver it's talking to, as desribed in spantaleev/matrix-docker-ansible-deploy#2583

Element X (at least on iOS) does not seem to be doing such checks and does not care what /client/server.json says.

So it may be that element-web needs to stop caring too, or that Element X needs to be fixed. In any case, it seems like /client/server.json may also benefit from advertising the correct public homeserver URL anyway.

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Working on this, I've also noticed that #378 (ae73ace) which introduced UNIX socket support (to SYNCV3_SERVER and SYNCV3_BINDADDR) may also benefit from this current patch landing.

When SYNCV3_SERVER is pointed to a UNIX socket, it also ends up in the /client/server.json file ("server": "/socket.sock", ..} which I suppose clients like Element will not like. People using UNIX sockets can use the new SYNCV3_SERVER_PUB environment variable for the public homeserver URL.

I also believe that validation checks in cmd/syncv3/main.go should be adjusted, so that when SYNCV3_SERVER is pointed to a socket file, SYNCV3_SERVER_PUB would be required.

If you agree with this, I could prepare another PR.. Or feel free to quickly fix it up yourselves.

[kegsay]

So it may be that element-web needs to stop caring too

This. /client/server.json isn't part of the MSC, and element-web shouldn't care about this nowadays. The SYNCV3_SERVER env var is an internal URL, and really we probably shouldn't be leaking it outside (via /client/server.json). Adding another env var just confuses things more.

[spantaleev]

Sounds good!

I wonder why element-web is trying to read it from there though. Perhaps that should be fixed first.

[kegsay]

Nothing to do here, so closing. Element-Web should not be checking /client/server.json anymore.