From 63403aa7a57704cde86344b48390d16b1d74b035 Mon Sep 17 00:00:00 2001
From: Mark Haines <mark.haines@matrix.org>
Date: Thu, 8 Jan 2015 17:07:28 +0000
Subject: [PATCH] Check the existance and versions of necessary modules when
 starting synapse, log which modules are used

---
 synapse/app/homeserver.py      |  5 +++
 synapse/python_dependencies.py | 80 ++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 synapse/python_dependencies.py

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index fba43aa2b..43b5c2614 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -18,6 +18,8 @@ from synapse.storage import prepare_database, UpgradeDatabaseException
 
 from synapse.server import HomeServer
 
+from synapse.python_dependencies import check_requirements
+
 from twisted.internet import reactor
 from twisted.enterprise import adbapi
 from twisted.web.resource import Resource
@@ -200,6 +202,8 @@ def setup():
 
     config.setup_logging()
 
+    check_requirements()
+
     logger.info("Server hostname: %s", config.server_name)
     logger.info("Server version: %s", synapse.__version__)
 
@@ -280,6 +284,7 @@ def run():
 
 def main():
     with LoggingContext("main"):
+        check_requirements()
         setup()
 
 
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
new file mode 100644
index 000000000..b1fae991e
--- /dev/null
+++ b/synapse/python_dependencies.py
@@ -0,0 +1,80 @@
+import logging
+from distutils.version import LooseVersion
+
+logger = logging.getLogger(__name__)
+
+REQUIREMENTS = {
+    "syutil==0.0.2": ["syutil"],
+    "matrix_angular_sdk==0.6.0": ["syweb==0.6.0"],
+    "Twisted>=14.0.0": ["twisted>=14.0.0"],
+    "service_identity>=1.0.0": ["service_identity>=1.0.0"],
+    "pyopenssl>=0.14": ["OpenSSL>=0.14"],
+    "pyyaml": ["yaml"],
+    "pyasn1": ["pyasn1"],
+    "pynacl": ["nacl"],
+    "daemonize": ["daemonize"],
+    "py-bcrypt": ["bcrypt"],
+    "frozendict>=0.4": ["frozendict"],
+    "pillow": ["PIL"],
+}
+
+
+class MissingRequirementError(Exception):
+    pass
+
+
+def check_requirements():
+    """Checks that all the modules needed by synapse have been correctly
+    installed and are at the correct version"""
+    for dependency, module_requirements in REQUIREMENTS.items():
+        for module_requirement in module_requirements:
+            if ">=" in module_requirement:
+                module_name, required_version = module_requirement.split(">=")
+                version_test = ">="
+            elif "==" in module_requirement:
+                module_name, required_version = module_requirement.split("==")
+                version_test = "=="
+            else:
+                module_name = module_requirement
+                version_test = None
+
+            try:
+                module = __import__(module_name)
+            except ImportError:
+                logging.exception(
+                    "Can't import %r which is part of %r",
+                    module_name, dependency
+                )
+                raise MissingRequirementError(
+                    "Can't import %r which is part of %r"
+                    % (module_name, dependency)
+                )
+            version = getattr(module, "__version__", None)
+            file_path = getattr(module, "__file__", None)
+            logger.info(
+                "Using %r version %r from %r to satisfy %r",
+                module_name, version, file_path, dependency
+            )
+
+            if version_test == ">=":
+                if version is None:
+                    raise MissingRequirementError(
+                        "Version of %r isn't set as __version__ of module %r"
+                        % (dependency, module_name)
+                    )
+                if LooseVersion(version) < LooseVersion(required_version):
+                    raise MissingRequirementError(
+                        "Version of %r in %r is too old. %r < %r"
+                        % (dependency, file_path, version, required_version)
+                    )
+            elif version_test == "==":
+                if version is None:
+                    raise MissingRequirementError(
+                        "Version of %r isn't set as __version__ of module %r"
+                        % (dependency, module_name)
+                    )
+                if LooseVersion(version) != LooseVersion(required_version):
+                    raise MissingRequirementError(
+                        "Unexpected version of %r in %r. %r != %r"
+                        % (dependency, file_path, version, required_version)
+                    )