I think the configuration file, as shown in the bug report, has a bug; the last
location should probably be
<Location /snac>
ProxyPass http://127.0.0.1:8001/snac
ProxyPreserveHost On
RequestHeader set X-Forwarded-Proto 'https' env=HTTPS
</Location>
Note the leading /snac at the end of ProxyPass; with the proposed
configuration, the data reaches the snac server correctly, but the path is
truncated to /USER/inbox (instead of the expected /snac/USER/inbox), and as the
path is used in the HTTP Signature, the validation fails.
Hope it helps (I'm by no means an Apache2 expert and use nginx myself with
snac).
Best regards,
Ángel Ortega
