in funkwhale_proxy.conf I get

global proxy conf

proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Host $host:$server_port;
proxy_set_header X-Forwarded-Port $server_port;
proxy_redirect off;

websocket support

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;

# global proxy conf
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Host $host:$server_port;
proxy_set_header X-Forwarded-Port $server_port;
proxy_redirect off;

# websocket support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;

In reply to @zulu:portdescale.fr
are you sure I hardcode my domain?

Either that, or you ensure your outper proxy sets the proper X-Forwarded-* headers, and you alias to them here:

proxy_set_header X-Forwarded-For $http_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $http_x_forwarded_proto;
proxy_set_header X-Forwarded-Host $http_x_forwarded_host;
proxy_set_header X-Forwarded-Port $http_x_forwarded_port;

In reply to @zulu:portdescale.fr
the X-Forwarded-* directive you want I move are the one before all the location?

ok:

# global proxy conf
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
#proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Proto "https";
#proxy_set_header X-Forwarded-Host $host:$server_port;
proxy_set_header X-Forwarded-Host "zic.example.com";
#proxy_set_header X-Forwarded-Port $server_port;
proxy_set_header X-Forwarded-Port "443";
proxy_redirect off;

# websocket support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;

pr 03 22:29:26 cop22 celery[27660]: [2020-04-03 20:29:26,963: CRITICAL/MainProcess] beat raised exception <class '_dbm.error'>: error('cannot add item to database')
Apr 03 22:29:26 cop22 celery[27660]: Traceback (most recent call last):
Apr 03 22:29:26 cop22 celery[27660]:   File "/srv/funkwhale/virtualenv/lib/python3.7/site-packages/kombu/utils/objects.py", line 42, in __get__
Apr 03 22:29:26 cop22 celery[27660]:     return obj.__dict__[self.__name__]
Apr 03 22:29:26 cop22 celery[27660]: KeyError: 'scheduler'
Apr 03 22:29:26 cop22 celery[27660]: During handling of the above exception, another exception occurred:
Apr 03 22:29:26 cop22 celery[27660]: Traceback (most recent call last):
Apr 03 22:29:26 cop22 celery[27660]:   File "/usr/lib/python3.7/shelve.py", line 111, in __getitem__
Apr 03 22:29:26 cop22 celery[27660]:     value = self.cache[key]
Apr 03 22:29:26 cop22 celery[27660]: KeyError: 'entries'
Apr 03 22:29:26 cop22 celery[27660]: During handling of the above exception, another exception occurred:
Apr 03 22:29:26 cop22 celery[27660]: Traceback (most recent call last):
Apr 03 22:29:26 cop22 celery[27660]:   File "/srv/funkwhale/virtualenv/lib/python3.7/site-packages/celery/beat.py", line 524, in _create_schedule
Apr 03 22:29:26 cop22 celery[27660]:     self._store[str('entries')]
Apr 03 22:29:26 cop22 celery[27660]:   File "/usr/lib/python3.7/shelve.py", line 113, in __getitem__
Apr 03 22:29:26 cop22 celery[27660]:     f = BytesIO(self.dict[key.encode(self.keyencoding)])
Apr 03 22:29:26 cop22 celery[27660]: KeyError: b'entries'
Apr 03 22:29:26 cop22 celery[27660]: During handling of the above exception, another exception occurred:
Apr 03 22:29:26 cop22 celery[27660]: Traceback (most recent call last):

In reply to @zulu:portdescale.fr

ok:

# global proxy conf
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
#proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Proto "https";
#proxy_set_header X-Forwarded-Host $host:$server_port;
proxy_set_header X-Forwarded-Host "zic.example.com";
#proxy_set_header X-Forwarded-Port $server_port;
proxy_set_header X-Forwarded-Port "443";
proxy_redirect off;

# websocket support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;

In reply to @zulu:portdescale.fr
don't know what database it is refering.. redis and postgres are running...