Error if macaroon key is missing from config

Currently we store all access tokens in the DB, and fall back to that
check if we can't validate the macaroon, so our fallback works here, but
for guests, their macaroons don't get persisted, so we don't get to
find them in the database. Each restart, we generate a new ephemeral
key, so guests lose access after each server restart.

I tried to fix up the config stuff to be less insane, but gave up, so
instead I bolt on yet another piece of custom one-off insanity.

Also, add some basic tests for config generation and loading.

4 files changed, 57 insertions, 23 deletions

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 0a6a19033d..89238cb7e3 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -24,6 +24,7 @@ import resource
 import subprocess
 import sys
 import time
+from synapse.config._base import ConfigError
 
 from synapse.python_dependencies import (
     check_requirements, DEPENDENCY_LINKS
@@ -350,11 +351,20 @@ def setup(config_options):
     Returns:
         HomeServer
     """
-    config = HomeServerConfig.load_config(
-        "Synapse Homeserver",
-        config_options,
-        generate_section="Homeserver"
-    )
+    try:
+        config = HomeServerConfig.load_config(
+            "Synapse Homeserver",
+            config_options,
+            generate_section="Homeserver"
+        )
+    except ConfigError as e:
+        sys.stderr.write("\n" + e.message + "\n")
+        sys.exit(1)
+
+    if not config:
+        # If a config isn't returned, and an exception isn't raised, we're just
+        # generating config files and shouldn't try to continue.
+        sys.exit(0)
 
     config.setup_logging()
 
diff --git a/synapse/config/__main__.py b/synapse/config/__main__.py
index ea9e7907a6..0a3b70e11f 100644
--- a/synapse/config/__main__.py
+++ b/synapse/config/__main__.py
@@ -12,6 +12,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from synapse.config._base import ConfigError
 
 if __name__ == "__main__":
     import sys
@@ -21,7 +22,11 @@ if __name__ == "__main__":
 
     if action == "read":
         key = sys.argv[2]
-        config = HomeServerConfig.load_config("", sys.argv[3:])
+        try:
+            config = HomeServerConfig.load_config("", sys.argv[3:])
+        except ConfigError as e:
+            sys.stderr.write("\n" + e.message + "\n")
+            sys.exit(1)
 
         print getattr(config, key)
         sys.exit(0)
diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index a9304a11ba..15d78ff33a 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -17,7 +17,6 @@ import argparse
 import errno
 import os
 import yaml
-import sys
 from textwrap import dedent
 
 
@@ -136,13 +135,20 @@ class Config(object):
                 results.append(getattr(cls, name)(self, *args, **kargs))
         return results
 
-    def generate_config(self, config_dir_path, server_name, report_stats=None):
+    def generate_config(
+            self,
+            config_dir_path,
+            server_name,
+            is_generating_file,
+            report_stats=None,
+    ):
         default_config = "# vim:ft=yaml\n"
 
         default_config += "\n\n".join(dedent(conf) for conf in self.invoke_all(
             "default_config",
             config_dir_path=config_dir_path,
             server_name=server_name,
+            is_generating_file=is_generating_file,
             report_stats=report_stats,
         ))
 
@@ -244,8 +250,10 @@ class Config(object):
 
                 server_name = config_args.server_name
                 if not server_name:
-                    print "Must specify a server_name to a generate config for."
-                    sys.exit(1)
+                    raise ConfigError(
+                        "Must specify a server_name to a generate config for."
+                        " Pass -H server.name."
+                    )
                 if not os.path.exists(config_dir_path):
                     os.makedirs(config_dir_path)
                 with open(config_path, "wb") as config_file:
@@ -253,6 +261,7 @@ class Config(object):
                         config_dir_path=config_dir_path,
                         server_name=server_name,
                         report_stats=(config_args.report_stats == "yes"),
+                        is_generating_file=True
                     )
                     obj.invoke_all("generate_files", config)
                     config_file.write(config_bytes)
@@ -266,7 +275,7 @@ class Config(object):
                     "If this server name is incorrect, you will need to"
                     " regenerate the SSL certificates"
                 )
-                sys.exit(0)
+                return
             else:
                 print (
                     "Config file %r already exists. Generating any missing key"
@@ -302,25 +311,25 @@ class Config(object):
             specified_config.update(yaml_config)
 
         if "server_name" not in specified_config:
-            sys.stderr.write("\n" + MISSING_SERVER_NAME + "\n")
-            sys.exit(1)
+            raise ConfigError(MISSING_SERVER_NAME)
 
         server_name = specified_config["server_name"]
         _, config = obj.generate_config(
             config_dir_path=config_dir_path,
-            server_name=server_name
+            server_name=server_name,
+            is_generating_file=False,
         )
         config.pop("log_config")
         config.update(specified_config)
         if "report_stats" not in config:
-            sys.stderr.write(
-                "\n" + MISSING_REPORT_STATS_CONFIG_INSTRUCTIONS + "\n" +
-                MISSING_REPORT_STATS_SPIEL + "\n")
-            sys.exit(1)
+            raise ConfigError(
+                MISSING_REPORT_STATS_CONFIG_INSTRUCTIONS + "\n" +
+                MISSING_REPORT_STATS_SPIEL
+            )
 
         if generate_keys:
             obj.invoke_all("generate_files", config)
-            sys.exit(0)
+            return
 
         obj.invoke_all("read_config", config)
 
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 90ea19bd4b..9b6dacc5b8 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -33,12 +33,24 @@ class RegistrationConfig(Config):
 
         self.registration_shared_secret = config.get("registration_shared_secret")
         self.macaroon_secret_key = config.get("macaroon_secret_key")
+        if self.macaroon_secret_key is None:
+            raise Exception(
+                "Config is missing missing macaroon_secret_key - please set it"
+                " in your config file."
+            )
         self.bcrypt_rounds = config.get("bcrypt_rounds", 12)
         self.trusted_third_party_id_servers = config["trusted_third_party_id_servers"]
         self.allow_guest_access = config.get("allow_guest_access", False)
 
-    def default_config(self, **kwargs):
+    def default_config(self, is_generating_file=False, **kwargs):
         registration_shared_secret = random_string_with_symbols(50)
+
+        macaroon_line = ""
+        if is_generating_file:
+            macaroon_line += '\n        macaroon_secret_key: "%s"\n' % (
+                random_string_with_symbols(50),
+            )
+
         macaroon_secret_key = random_string_with_symbols(50)
         return """\
         ## Registration ##
@@ -49,9 +61,7 @@ class RegistrationConfig(Config):
         # If set, allows registration by anyone who also has the shared
         # secret, even if registration is otherwise disabled.
         registration_shared_secret: "%(registration_shared_secret)s"
-
-        macaroon_secret_key: "%(macaroon_secret_key)s"
-
+%(macaroon_line)s
         # Set the number of bcrypt rounds used to generate password hash.
         # Larger numbers increase the work factor needed to generate the hash.
         # The default number of rounds is 12.