Make the logging level configurable

contrib/docker/conf/log.config

@@ -17,13 +17,13 @@ handlers:
 
 loggers:
     synapse:
-        level: INFO
+        level: {{ SYNAPSE_LOG_LEVEL or "WARNING" }}
 
     synapse.storage.SQL:
         # beware: increasing this to DEBUG will make synapse log sensitive
         # information such as access tokens.
-        level: INFO
+        level: {{ SYNAPSE_LOG_LEVEL or "WARNING" }}
 
 root:
-    level: INFO
+    level: {{ SYNAPSE_LOG_LEVEL or "WARNING" }}
     handlers: [console]

contrib/docker/docker-compose.yml

@@ -15,6 +15,7 @@ services:
       - SYNAPSE_SERVER_NAME=my.matrix.host
       - SYNAPSE_REPORT_STATS=no
       - SYNAPSE_ENABLE_REGISTRATION=yes
+      - SYNAPSE_LOG_LEVEL=INFO
       - POSTGRES_PASSWORD=changeme
     volumes:
       # You may either store all the files in a local folder