A guide to the request log lines format.

changelog.d/8436.doc

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+Add a new guide to decoding request logs.

docs/request_log.md

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+# Request log format
+
+HTTP request logs are written by synapse (see synapse/http/site.py for details.
+
+See the following for how to decode the dense data available here.
+
+```
+2020-10-01 12:00:00,000 - synapse.access.http.8008 - 311 - INFO - PUT-1000- 192.168.0.1 - 8008 - {another-matrix-server.com} Processed request: 0.100sec/-0.000sec (0.000sec, 0.000sec) (0.001sec/0.090sec/3) 11B 200 "PUT /_matrix/federation/v1/send/1600000000000 HTTP/1.1" "Synapse/1.20.1" [0 dbevts]
+-AAAAAAAAAAAAAAAAAAAAA-   -BBBBBBBBBBBBBBBBBBBBBB-   -C-   -DD-   -EEEEEE-  -FFFFFFFFF-   -GG-    -HHHHHHHHHHHHHHHHHHHHHHH-                     -IIIIII- -JJJJJJJ-  -KKKKKK-, -LLLLLL-  -MMMMMMM- -NNNNNN- O  -P- -Q-  -RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR-   -SSSSSSSSSSSS-   -TTTTTT-
+```
+
+
+| Part  | Explaination | 
+| ----- | ------------ |
+| AAAA  | Timestamp request was logged (not recieved) |
+| BBBB  | Logger name (usually the same as the python class ) |
+| CCCC  | Line number in code |
+| DDDD  | Log Level |
+| EEEE  | Request Identifier (This identifier is shared by related log lines)|
+| FFFF  | Source IP (Or X-Forwarded-For if enabled) |
+| GGGG  | Server Port |
+| HHHH  | Federated Server or Local User making request (blank if unauthenticated or not supplied) |
+| IIII  | Total Time to process |
+| JJJJ  | Time to send response over network once generated |
+| KKKK  | Userland time |
+| LLLL  | System time |
+| MMMM  | Total time waiting for DB connections |
+| NNNN  | Total time waiting for response to DB queries |
+| OOOO  | Count of DB transactions performed |
+| PPPP  | Response body size |
+| QQQQ  | Response status code |
+| RRRR  | Request |
+| SSSS  | User-agent |
+| TTTT  | Events fetched from DB to service this request |