Docker image no longer starts if you set SYNAPSE_SMTP_HOST

[richvdh]

As far as I can tell, the SYNAPSE_SMTP_* settings were never used, because email_notifs was set to false in the homeserver.yaml used by the docker image. Nevertheless the documentation kinda encourages you to set the SYNAPSE_SMTP_* settings. Those that did so will now find that their servers refuse to start, with:

RuntimeError: email.password_reset_behaviour is set to 'local' but no public_baseurl is set. This is necessary to generate password reset links

[richvdh]

The workarounds for now are either:

• don't set the SYNAPSE_SMTP_* env vars (will disable password reset on your server)
• use a custom config file via SYNAPSE_CONFIG_PATH

[anoadragon453]

A quick fix before figuring out the whole Docker mess is just to add a SYNAPSE_PUBLIC_BASEURL environment variable. This behaviour has been implemented in #5519.

But we should really figure this out :/

[richvdh]

I'm not convinced adding a SYNAPSE_PUBLIC_BASEURL is the best approach.

We're going to be telling people to switch to the SYNAPSE_CONFIG_PATH approach, so rather than having them add a SYNAPSE_PUBLIC_BASEURL, I think we should tell them to switch to a generated file.

The only question is whether we can do something better for people whose working configs have been broken by 1.0, like disabling password resets altogether?

Given the SYNAPSE_SMTP_ vars are unused in synapse <0.99, maybe we should just remove them, and skip generating the email config section?

[richvdh]

(incidentally it might be good to do that against the release branch and we can update the docker image on dockerhub.)

[anoadragon453]

Given the SYNAPSE_SMTP_ vars are unused in synapse <0.99, maybe we should just remove them, and skip generating the email config section?

This sounds best to me, considering, as you say, they were never actually used.

[hawkowl]

Because of #5518, I believe we can say "use a proper config" here, and close it?

[richvdh]

Because of #5518, I believe we can say "use a proper config" here, and close it?

As per #5430 (comment): I'd prefer not to break peoples' working configs, and I think we can do better.

[xobs]

The README.md on https://hub.docker.com/r/matrixdotorg/synapse still documents those variables, so that should first be removed prior to closing this issue.