Update the dockerfile to be Debian based, not Alpine based

[hawkowl]

This means we don't use libressl instead of openssl, and we get to use a lot of the manylinux1 wheels vs building them with headers ourselves.

[richvdh]

seems like a good idea

[richvdh]

we need a bunch of this stuff for features that people expect to work in the docker image.

[hawkowl]

so because we use the available wheels, we don't, because cffi and etc ship what's required.

[richvdh]

I think we still need xmlsec (or, as debian calls it, xmlsec1) at least. pysaml relies on the /usr/bin/xmlsec1 binary.

[hawkowl]

I added some --version functionality so that we can check that Synapse, as well as its optional dependencies, are functional. On build, I get:

Synapse/1.6.0rc1

Additional functionality:
matrix-synapse-ldap3   [  OK  ]
postgres               [  OK  ]
resources.consent      [  OK  ]
acme                   [  OK  ]
saml2                  [  OK  ]
systemd                [NOT OK]
url_preview            [  OK  ]
sentry                 [  OK  ]
opentracing            [  OK  ]
jwt                    [  OK  ]

old

[richvdh]

when I run this I get:

$ docker run --rm -it -e SYNAPSE_SERVER_NAME=test -e SYNAPSE_REPORT_STATS=no matrixdotorg/synapse generate
Container running as UserID 0:0, ENV (or defaults) requests 991:991
Creating log config /data/test.log.config
Traceback (most recent call last):
  File "/start.py", line 259, in <module>
    main(sys.argv, os.environ)
  File "/start.py", line 201, in main
    return run_generate_config(environ, ownership)
  File "/start.py", line 176, in run_generate_config
    os.execv("/sbin/su-exec", args)
FileNotFoundError: [Errno 2] No such file or directory

I'm basically a bit concerned this hasn't been tested.

[richvdh]

I think we still need xmlsec (or, as debian calls it, xmlsec1) at least. pysaml relies on the /usr/bin/xmlsec1 binary.

[richvdh]

for future reference: this is probably a thing we should do if only to bring the docker image into line with other distros wrt which ssl library we use (see https://cryptography.io/en/latest/installation/)

[richvdh]

Having said that: can't we just build against openssl-dev rather than libressl-dev? (see https://pkgs.alpinelinux.org/contents?file=libssl.so&path=&name=&branch=edge&arch=x86_64)

[richvdh]

related: #7000

[clokep]

I'm going to close this since it hasn't been updated in ~6 months. If this is necessary in the future we can re-open this PR.