Self-checks against the .well-known URIs look for the HTTP header
"Access-Control-Allow-Origin" indicating that the remode endpoint
supports CORS. But the remote server is not required to include
said header in the response if the HTTP request does not include
the "Origin" header. This is in accordance with the specification
[1] stating: 'A CORS request is an HTTP request that includes an
"Origin" header.'
This is in fact true for Gitlab pages hosting and that's why the
issue was identified.
Let's specify "Origin" header in the respective uri tasks performing
the HTTP request and ensure a CORS request.
[1] https://fetch.spec.whatwg.org/#http-requests
We have a flow like this:
1. matrix.DOMAIN vhost (matrix-domain.conf)
2. matrix-synapse vhost (matrix-synapse.conf); or matrix-corporal container, if enabled
3. (optional) matrix-synapse vhost (matrix-synapse.conf), if matrix-corporal enabled
4. matrix-synapse container
We are setting `X-Forwarded-For` correctly in step #1, but were
overwriting it in step #2 with something inaccurate.
Not doing anything in step #2 is better than doing the wrong thing.
It's probably best if we append another reverse-proxy address there
though, although what we're doing now (with this patch) seems to yield
the correct result (when matrix-corporal is not enabled).
When matrix-corporal is enabled, we still seem to do the wrong thing for
some reason. It's something to be fixed later on.
During first setup postgres takes its time to get up and running, resulting in "postgres in startup" exceptions from synapse if you run without additional services that come in between. Hence suggesting increasing the time a bit to avoid having an error which heals itself and thus is hard to spot for newcomers.