structured_logging.html 25 KB

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  149. <h1 id="structured-logging"><a class="header" href="#structured-logging">Structured Logging</a></h1>
  150. <p>A structured logging system can be useful when your logs are destined for a
  151. machine to parse and process. By maintaining its machine-readable characteristics,
  152. it enables more efficient searching and aggregations when consumed by software
  153. such as the &quot;ELK stack&quot;.</p>
  154. <p>Synapse's structured logging system is configured via the file that Synapse's
  155. <code>log_config</code> config option points to. The file should include a formatter which
  156. uses the <code>synapse.logging.TerseJsonFormatter</code> class included with Synapse and a
  157. handler which uses the above formatter.</p>
  158. <p>There is also a <code>synapse.logging.JsonFormatter</code> option which does not include
  159. a timestamp in the resulting JSON. This is useful if the log ingester adds its
  160. own timestamp.</p>
  161. <p>A structured logging configuration looks similar to the following:</p>
  162. <pre><code class="language-yaml">version: 1
  163. formatters:
  164. structured:
  165. class: synapse.logging.TerseJsonFormatter
  166. handlers:
  167. file:
  168. class: logging.handlers.TimedRotatingFileHandler
  169. formatter: structured
  170. filename: /path/to/my/logs/homeserver.log
  171. when: midnight
  172. backupCount: 3 # Does not include the current log file.
  173. encoding: utf8
  174. loggers:
  175. synapse:
  176. level: INFO
  177. handlers: [remote]
  178. synapse.storage.SQL:
  179. level: WARNING
  180. </code></pre>
  181. <p>The above logging config will set Synapse as 'INFO' logging level by default,
  182. with the SQL layer at 'WARNING', and will log to a file, stored as JSON.</p>
  183. <p>It is also possible to figure Synapse to log to a remote endpoint by using the
  184. <code>synapse.logging.RemoteHandler</code> class included with Synapse. It takes the
  185. following arguments:</p>
  186. <ul>
  187. <li><code>host</code>: Hostname or IP address of the log aggregator.</li>
  188. <li><code>port</code>: Numerical port to contact on the host.</li>
  189. <li><code>maximum_buffer</code>: (Optional, defaults to 1000) The maximum buffer size to allow.</li>
  190. </ul>
  191. <p>A remote structured logging configuration looks similar to the following:</p>
  192. <pre><code class="language-yaml">version: 1
  193. formatters:
  194. structured:
  195. class: synapse.logging.TerseJsonFormatter
  196. handlers:
  197. remote:
  198. class: synapse.logging.RemoteHandler
  199. formatter: structured
  200. host: 10.1.2.3
  201. port: 9999
  202. loggers:
  203. synapse:
  204. level: INFO
  205. handlers: [remote]
  206. synapse.storage.SQL:
  207. level: WARNING
  208. </code></pre>
  209. <p>The above logging config will set Synapse as 'INFO' logging level by default,
  210. with the SQL layer at 'WARNING', and will log JSON formatted messages to a
  211. remote endpoint at 10.1.2.3:9999.</p>
  212. <h2 id="upgrading-from-legacy-structured-logging-configuration"><a class="header" href="#upgrading-from-legacy-structured-logging-configuration">Upgrading from legacy structured logging configuration</a></h2>
  213. <p>Versions of Synapse prior to v1.23.0 included a custom structured logging
  214. configuration which is deprecated. It used a <code>structured: true</code> flag and
  215. configured <code>drains</code> instead of <code>handlers</code> and <code>formatters</code>.</p>
  216. <p>Synapse currently automatically converts the old configuration to the new
  217. configuration, but this will be removed in a future version of Synapse. The
  218. following reference can be used to update your configuration. Based on the drain
  219. <code>type</code>, we can pick a new handler:</p>
  220. <ol>
  221. <li>For a type of <code>console</code>, <code>console_json</code>, or <code>console_json_terse</code>: a handler
  222. with a class of <code>logging.StreamHandler</code> and a <code>stream</code> of <code>ext://sys.stdout</code>
  223. or <code>ext://sys.stderr</code> should be used.</li>
  224. <li>For a type of <code>file</code> or <code>file_json</code>: a handler of <code>logging.FileHandler</code> with
  225. a location of the file path should be used.</li>
  226. <li>For a type of <code>network_json_terse</code>: a handler of <code>synapse.logging.RemoteHandler</code>
  227. with the host and port should be used.</li>
  228. </ol>
  229. <p>Then based on the drain <code>type</code> we can pick a new formatter:</p>
  230. <ol>
  231. <li>For a type of <code>console</code> or <code>file</code> no formatter is necessary.</li>
  232. <li>For a type of <code>console_json</code> or <code>file_json</code>: a formatter of
  233. <code>synapse.logging.JsonFormatter</code> should be used.</li>
  234. <li>For a type of <code>console_json_terse</code> or <code>network_json_terse</code>: a formatter of
  235. <code>synapse.logging.TerseJsonFormatter</code> should be used.</li>
  236. </ol>
  237. <p>For each new handler and formatter they should be added to the logging configuration
  238. and then assigned to either a logger or the root logger.</p>
  239. <p>An example legacy configuration:</p>
  240. <pre><code class="language-yaml">structured: true
  241. loggers:
  242. synapse:
  243. level: INFO
  244. synapse.storage.SQL:
  245. level: WARNING
  246. drains:
  247. console:
  248. type: console
  249. location: stdout
  250. file:
  251. type: file_json
  252. location: homeserver.log
  253. </code></pre>
  254. <p>Would be converted into a new configuration:</p>
  255. <pre><code class="language-yaml">version: 1
  256. formatters:
  257. json:
  258. class: synapse.logging.JsonFormatter
  259. handlers:
  260. console:
  261. class: logging.StreamHandler
  262. location: ext://sys.stdout
  263. file:
  264. class: logging.FileHandler
  265. formatter: json
  266. filename: homeserver.log
  267. loggers:
  268. synapse:
  269. level: INFO
  270. handlers: [console, file]
  271. synapse.storage.SQL:
  272. level: WARNING
  273. </code></pre>
  274. <p>The new logging configuration is a bit more verbose, but significantly more
  275. flexible. It allows for configuration that were not previously possible, such as
  276. sending plain logs over the network, or using different handlers for different
  277. modules.</p>
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