Give `public_baseurl` a default value (#9159)

14 files changed, 48 insertions, 83 deletions

diff --git a/changelog.d/9159.feature b/changelog.d/9159.feature
new file mode 100644
index 0000000000..b7748757de
--- /dev/null
+++ b/changelog.d/9159.feature
@@ -0,0 +1 @@
+Give the `public_baseurl` a default value, if it is not explicitly set in the configuration file.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index ae995efe9b..7fdd798d70 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -67,11 +67,16 @@ pid_file: DATADIR/homeserver.pid
 #
 #web_client_location: https://riot.example.com/
 
-# The public-facing base URL that clients use to access this HS
-# (not including _matrix/...). This is the same URL a user would
-# enter into the 'custom HS URL' field on their client. If you
-# use synapse with a reverse proxy, this should be the URL to reach
-# synapse via the proxy.
+# The public-facing base URL that clients use to access this Homeserver (not
+# including _matrix/...). This is the same URL a user might enter into the
+# 'Custom Homeserver URL' field on their client. If you use Synapse with a
+# reverse proxy, this should be the URL to reach Synapse via the proxy.
+# Otherwise, it should be the URL to reach Synapse's client HTTP listener (see
+# 'listeners' below).
+#
+# If this is left unset, it defaults to 'https://<server_name>/'. (Note that
+# that will not work unless you configure Synapse or a reverse-proxy to listen
+# on port 443.)
 #
 #public_baseurl: https://example.com/
 
@@ -1150,8 +1155,9 @@ account_validity:
   # send an email to the account's email address with a renewal link. By
   # default, no such emails are sent.
   #
-  # If you enable this setting, you will also need to fill out the 'email' and
-  # 'public_baseurl' configuration sections.
+  # If you enable this setting, you will also need to fill out the 'email'
+  # configuration section. You should also check that 'public_baseurl' is set
+  # correctly.
   #
   #renew_at: 1w
 
@@ -1242,8 +1248,7 @@ account_validity:
 # The identity server which we suggest that clients should use when users log
 # in on this server.
 #
-# (By default, no suggestion is made, so it is left up to the client.
-# This setting is ignored unless public_baseurl is also set.)
+# (By default, no suggestion is made, so it is left up to the client.)
 #
 #default_identity_server: https://matrix.org
 
@@ -1268,8 +1273,6 @@ account_validity:
 # by the Matrix Identity Service API specification:
 # https://matrix.org/docs/spec/identity_service/latest
 #
-# If a delegate is specified, the config option public_baseurl must also be filled out.
-#
 account_threepid_delegates:
     #email: https://example.com     # Delegate email sending to example.com
     #msisdn: http://localhost:8090  # Delegate SMS sending to this local process
@@ -1901,9 +1904,9 @@ sso:
     # phishing attacks from evil.site. To avoid this, include a slash after the
     # hostname: "https://my.client/".
     #
-    # If public_baseurl is set, then the login fallback page (used by clients
-    # that don't natively support the required login flows) is whitelisted in
-    # addition to any URLs in this list.
+    # The login fallback page (used by clients that don't natively support the
+    # required login flows) is automatically whitelisted in addition to any URLs
+    # in this list.
     #
     # By default, this list is empty.
     #
diff --git a/synapse/api/urls.py b/synapse/api/urls.py
index 6379c86dde..e36aeef31f 100644
--- a/synapse/api/urls.py
+++ b/synapse/api/urls.py
@@ -42,8 +42,6 @@ class ConsentURIBuilder:
         """
         if hs_config.form_secret is None:
             raise ConfigError("form_secret not set in config")
-        if hs_config.public_baseurl is None:
-            raise ConfigError("public_baseurl not set in config")
 
         self._hmac_secret = hs_config.form_secret.encode("utf-8")
         self._public_baseurl = hs_config.public_baseurl
diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index 2931a88207..94144efc87 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -252,11 +252,12 @@ class Config:
         env = jinja2.Environment(loader=loader, autoescape=autoescape)
 
         # Update the environment with our custom filters
-        env.filters.update({"format_ts": _format_ts_filter})
-        if self.public_baseurl:
-            env.filters.update(
-                {"mxc_to_http": _create_mxc_to_http_filter(self.public_baseurl)}
-            )
+        env.filters.update(
+            {
+                "format_ts": _format_ts_filter,
+                "mxc_to_http": _create_mxc_to_http_filter(self.public_baseurl),
+            }
+        )
 
         for filename in filenames:
             # Load the template
diff --git a/synapse/config/emailconfig.py b/synapse/config/emailconfig.py
index d4328c46b9..6a487afd34 100644
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -166,11 +166,6 @@ class EmailConfig(Config):
             if not self.email_notif_from:
                 missing.append("email.notif_from")
 
-            # public_baseurl is required to build password reset and validation links that
-            # will be emailed to users
-            if config.get("public_baseurl") is None:
-                missing.append("public_baseurl")
-
             if missing:
                 raise ConfigError(
                     MISSING_PASSWORD_RESET_CONFIG_ERROR % (", ".join(missing),)
@@ -269,9 +264,6 @@ class EmailConfig(Config):
             if not self.email_notif_from:
                 missing.append("email.notif_from")
 
-            if config.get("public_baseurl") is None:
-                missing.append("public_baseurl")
-
             if missing:
                 raise ConfigError(
                     "email.enable_notifs is True but required keys are missing: %s"
diff --git a/synapse/config/oidc_config.py b/synapse/config/oidc_config.py
index 80a24cfbc9..df55367434 100644
--- a/synapse/config/oidc_config.py
+++ b/synapse/config/oidc_config.py
@@ -43,8 +43,6 @@ class OIDCConfig(Config):
             raise ConfigError(e.message) from e
 
         public_baseurl = self.public_baseurl
-        if public_baseurl is None:
-            raise ConfigError("oidc_config requires a public_baseurl to be set")
         self.oidc_callback_url = public_baseurl + "_synapse/oidc/callback"
 
     @property
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 740c3fc1b1..4bfc69cb7a 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -49,10 +49,6 @@ class AccountValidityConfig(Config):
 
             self.startup_job_max_delta = self.period * 10.0 / 100.0
 
-        if self.renew_by_email_enabled:
-            if "public_baseurl" not in synapse_config:
-                raise ConfigError("Can't send renewal emails without 'public_baseurl'")
-
         template_dir = config.get("template_dir")
 
         if not template_dir:
@@ -109,13 +105,6 @@ class RegistrationConfig(Config):
         account_threepid_delegates = config.get("account_threepid_delegates") or {}
         self.account_threepid_delegate_email = account_threepid_delegates.get("email")
         self.account_threepid_delegate_msisdn = account_threepid_delegates.get("msisdn")
-        if self.account_threepid_delegate_msisdn and not self.public_baseurl:
-            raise ConfigError(
-                "The configuration option `public_baseurl` is required if "
-                "`account_threepid_delegate.msisdn` is set, such that "
-                "clients know where to submit validation tokens to. Please "
-                "configure `public_baseurl`."
-            )
 
         self.default_identity_server = config.get("default_identity_server")
         self.allow_guest_access = config.get("allow_guest_access", False)
@@ -240,8 +229,9 @@ class RegistrationConfig(Config):
           # send an email to the account's email address with a renewal link. By
           # default, no such emails are sent.
           #
-          # If you enable this setting, you will also need to fill out the 'email' and
-          # 'public_baseurl' configuration sections.
+          # If you enable this setting, you will also need to fill out the 'email'
+          # configuration section. You should also check that 'public_baseurl' is set
+          # correctly.
           #
           #renew_at: 1w
 
@@ -332,8 +322,7 @@ class RegistrationConfig(Config):
         # The identity server which we suggest that clients should use when users log
         # in on this server.
         #
-        # (By default, no suggestion is made, so it is left up to the client.
-        # This setting is ignored unless public_baseurl is also set.)
+        # (By default, no suggestion is made, so it is left up to the client.)
         #
         #default_identity_server: https://matrix.org
 
@@ -358,8 +347,6 @@ class RegistrationConfig(Config):
         # by the Matrix Identity Service API specification:
         # https://matrix.org/docs/spec/identity_service/latest
         #
-        # If a delegate is specified, the config option public_baseurl must also be filled out.
-        #
         account_threepid_delegates:
             #email: https://example.com     # Delegate email sending to example.com
             #msisdn: http://localhost:8090  # Delegate SMS sending to this local process
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index 7b97d4f114..f33dfa0d6a 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -189,8 +189,6 @@ class SAML2Config(Config):
         import saml2
 
         public_baseurl = self.public_baseurl
-        if public_baseurl is None:
-            raise ConfigError("saml2_config requires a public_baseurl to be set")
 
         if self.saml2_grandfathered_mxid_source_attribute:
             optional_attributes.add(self.saml2_grandfathered_mxid_source_attribute)
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 7242a4aa8e..75ba161f35 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -161,7 +161,11 @@ class ServerConfig(Config):
         self.print_pidfile = config.get("print_pidfile")
         self.user_agent_suffix = config.get("user_agent_suffix")
         self.use_frozen_dicts = config.get("use_frozen_dicts", False)
-        self.public_baseurl = config.get("public_baseurl")
+        self.public_baseurl = config.get("public_baseurl") or "https://%s/" % (
+            self.server_name,
+        )
+        if self.public_baseurl[-1] != "/":
+            self.public_baseurl += "/"
 
         # Whether to enable user presence.
         self.use_presence = config.get("use_presence", True)
@@ -317,9 +321,6 @@ class ServerConfig(Config):
         # Always blacklist 0.0.0.0, ::
         self.federation_ip_range_blacklist.update(["0.0.0.0", "::"])
 
-        if self.public_baseurl is not None:
-            if self.public_baseurl[-1] != "/":
-                self.public_baseurl += "/"
         self.start_pushers = config.get("start_pushers", True)
 
         # (undocumented) option for torturing the worker-mode replication a bit,
@@ -740,11 +741,16 @@ class ServerConfig(Config):
         #
         #web_client_location: https://riot.example.com/
 
-        # The public-facing base URL that clients use to access this HS
-        # (not including _matrix/...). This is the same URL a user would
-        # enter into the 'custom HS URL' field on their client. If you
-        # use synapse with a reverse proxy, this should be the URL to reach
-        # synapse via the proxy.
+        # The public-facing base URL that clients use to access this Homeserver (not
+        # including _matrix/...). This is the same URL a user might enter into the
+        # 'Custom Homeserver URL' field on their client. If you use Synapse with a
+        # reverse proxy, this should be the URL to reach Synapse via the proxy.
+        # Otherwise, it should be the URL to reach Synapse's client HTTP listener (see
+        # 'listeners' below).
+        #
+        # If this is left unset, it defaults to 'https://<server_name>/'. (Note that
+        # that will not work unless you configure Synapse or a reverse-proxy to listen
+        # on port 443.)
         #
         #public_baseurl: https://example.com/
 
diff --git a/synapse/config/sso.py b/synapse/config/sso.py
index 366f0d4698..59be825532 100644
--- a/synapse/config/sso.py
+++ b/synapse/config/sso.py
@@ -64,11 +64,8 @@ class SSOConfig(Config):
         # gracefully to the client). This would make it pointless to ask the user for
         # confirmation, since the URL the confirmation page would be showing wouldn't be
         # the client's.
-        # public_baseurl is an optional setting, so we only add the fallback's URL to the
-        # list if it's provided (because we can't figure out what that URL is otherwise).
-        if self.public_baseurl:
-            login_fallback_url = self.public_baseurl + "_matrix/static/client/login"
-            self.sso_client_whitelist.append(login_fallback_url)
+        login_fallback_url = self.public_baseurl + "_matrix/static/client/login"
+        self.sso_client_whitelist.append(login_fallback_url)
 
     def generate_config_section(self, **kwargs):
         return """\
@@ -86,9 +83,9 @@ class SSOConfig(Config):
             # phishing attacks from evil.site. To avoid this, include a slash after the
             # hostname: "https://my.client/".
             #
-            # If public_baseurl is set, then the login fallback page (used by clients
-            # that don't natively support the required login flows) is whitelisted in
-            # addition to any URLs in this list.
+            # The login fallback page (used by clients that don't natively support the
+            # required login flows) is automatically whitelisted in addition to any URLs
+            # in this list.
             #
             # By default, this list is empty.
             #
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index c05036ad1f..f61844d688 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -476,8 +476,6 @@ class IdentityHandler(BaseHandler):
         except RequestTimedOutError:
             raise SynapseError(500, "Timed out contacting identity server")
 
-        assert self.hs.config.public_baseurl
-
         # we need to tell the client to send the token back to us, since it doesn't
         # otherwise know where to send it, so add submit_url response parameter
         # (see also MSC2078)
diff --git a/synapse/rest/well_known.py b/synapse/rest/well_known.py
index f591cc6c5c..241fe746d9 100644
--- a/synapse/rest/well_known.py
+++ b/synapse/rest/well_known.py
@@ -34,10 +34,6 @@ class WellKnownBuilder:
         self._config = hs.config
 
     def get_well_known(self):
-        # if we don't have a public_baseurl, we can't help much here.
-        if self._config.public_baseurl is None:
-            return None
-
         result = {"m.homeserver": {"base_url": self._config.public_baseurl}}
 
         if self._config.default_identity_server:
diff --git a/tests/rest/test_well_known.py b/tests/rest/test_well_known.py
index 14de0921be..c5e44af9f7 100644
--- a/tests/rest/test_well_known.py
+++ b/tests/rest/test_well_known.py
@@ -40,12 +40,3 @@ class WellKnownTests(unittest.HomeserverTestCase):
                 "m.identity_server": {"base_url": "https://testis"},
             },
         )
-
-    def test_well_known_no_public_baseurl(self):
-        self.hs.config.public_baseurl = None
-
-        channel = self.make_request(
-            "GET", "/.well-known/matrix/client", shorthand=False
-        )
-
-        self.assertEqual(channel.code, 404)
diff --git a/tests/utils.py b/tests/utils.py
index 977eeaf6ee..09614093bc 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -159,7 +159,6 @@ def default_config(name, parse=False):
             "remote": {"per_second": 10000, "burst_count": 10000},
         },
         "saml2_enabled": False,
-        "public_baseurl": None,
         "default_identity_server": None,
         "key_refresh_interval": 24 * 60 * 60 * 1000,
         "old_signing_keys": {},