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diff --git a/docs/structured_logging.md b/docs/structured_logging.md index decec9b8fa..b1281667e0 100644 --- a/docs/structured_logging.md +++ b/docs/structured_logging.md @@ -1,83 +1,161 @@ # Structured Logging -A structured logging system can be useful when your logs are destined for a machine to parse and process. By maintaining its machine-readable characteristics, it enables more efficient searching and aggregations when consumed by software such as the "ELK stack". +A structured logging system can be useful when your logs are destined for a +machine to parse and process. By maintaining its machine-readable characteristics, +it enables more efficient searching and aggregations when consumed by software +such as the "ELK stack". -Synapse's structured logging system is configured via the file that Synapse's `log_config` config option points to. The file must be YAML and contain `structured: true`. It must contain a list of "drains" (places where logs go to). +Synapse's structured logging system is configured via the file that Synapse's +`log_config` config option points to. The file should include a formatter which +uses the `synapse.logging.TerseJsonFormatter` class included with Synapse and a +handler which uses the above formatter. + +There is also a `synapse.logging.JsonFormatter` option which does not include +a timestamp in the resulting JSON. This is useful if the log ingester adds its +own timestamp. A structured logging configuration looks similar to the following: ```yaml -structured: true +version: 1 + +formatters: + structured: + class: synapse.logging.TerseJsonFormatter + +handlers: + file: + class: logging.handlers.TimedRotatingFileHandler + formatter: structured + filename: /path/to/my/logs/homeserver.log + when: midnight + backupCount: 3 # Does not include the current log file. + encoding: utf8 loggers: synapse: level: INFO + handlers: [remote] synapse.storage.SQL: level: WARNING - -drains: - console: - type: console - location: stdout - file: - type: file_json - location: homeserver.log ``` -The above logging config will set Synapse as 'INFO' logging level by default, with the SQL layer at 'WARNING', and will have two logging drains (to the console and to a file, stored as JSON). - -## Drain Types +The above logging config will set Synapse as 'INFO' logging level by default, +with the SQL layer at 'WARNING', and will log to a file, stored as JSON. -Drain types can be specified by the `type` key. +It is also possible to figure Synapse to log to a remote endpoint by using the +`synapse.logging.RemoteHandler` class included with Synapse. It takes the +following arguments: -### `console` +- `host`: Hostname or IP address of the log aggregator. +- `port`: Numerical port to contact on the host. +- `maximum_buffer`: (Optional, defaults to 1000) The maximum buffer size to allow. -Outputs human-readable logs to the console. +A remote structured logging configuration looks similar to the following: -Arguments: +```yaml +version: 1 -- `location`: Either `stdout` or `stderr`. +formatters: + structured: + class: synapse.logging.TerseJsonFormatter -### `console_json` +handlers: + remote: + class: synapse.logging.RemoteHandler + formatter: structured + host: 10.1.2.3 + port: 9999 -Outputs machine-readable JSON logs to the console. +loggers: + synapse: + level: INFO + handlers: [remote] + synapse.storage.SQL: + level: WARNING +``` -Arguments: +The above logging config will set Synapse as 'INFO' logging level by default, +with the SQL layer at 'WARNING', and will log JSON formatted messages to a +remote endpoint at 10.1.2.3:9999. -- `location`: Either `stdout` or `stderr`. +## Upgrading from legacy structured logging configuration -### `console_json_terse` +Versions of Synapse prior to v1.23.0 included a custom structured logging +configuration which is deprecated. It used a `structured: true` flag and +configured `drains` instead of ``handlers`` and `formatters`. -Outputs machine-readable JSON logs to the console, separated by newlines. This -format is not designed to be read and re-formatted into human-readable text, but -is optimal for a logging aggregation system. +Synapse currently automatically converts the old configuration to the new +configuration, but this will be removed in a future version of Synapse. The +following reference can be used to update your configuration. Based on the drain +`type`, we can pick a new handler: -Arguments: +1. For a type of `console`, `console_json`, or `console_json_terse`: a handler + with a class of `logging.StreamHandler` and a `stream` of `ext://sys.stdout` + or `ext://sys.stderr` should be used. +2. For a type of `file` or `file_json`: a handler of `logging.FileHandler` with + a location of the file path should be used. +3. For a type of `network_json_terse`: a handler of `synapse.logging.RemoteHandler` + with the host and port should be used. -- `location`: Either `stdout` or `stderr`. +Then based on the drain `type` we can pick a new formatter: -### `file` +1. For a type of `console` or `file` no formatter is necessary. +2. For a type of `console_json` or `file_json`: a formatter of + `synapse.logging.JsonFormatter` should be used. +3. For a type of `console_json_terse` or `network_json_terse`: a formatter of + `synapse.logging.TerseJsonFormatter` should be used. -Outputs human-readable logs to a file. +For each new handler and formatter they should be added to the logging configuration +and then assigned to either a logger or the root logger. -Arguments: +An example legacy configuration: -- `location`: An absolute path to the file to log to. +```yaml +structured: true -### `file_json` +loggers: + synapse: + level: INFO + synapse.storage.SQL: + level: WARNING -Outputs machine-readable logs to a file. +drains: + console: + type: console + location: stdout + file: + type: file_json + location: homeserver.log +``` -Arguments: +Would be converted into a new configuration: -- `location`: An absolute path to the file to log to. +```yaml +version: 1 -### `network_json_terse` +formatters: + json: + class: synapse.logging.JsonFormatter -Delivers machine-readable JSON logs to a log aggregator over TCP. This is -compatible with LogStash's TCP input with the codec set to `json_lines`. +handlers: + console: + class: logging.StreamHandler + location: ext://sys.stdout + file: + class: logging.FileHandler + formatter: json + filename: homeserver.log -Arguments: +loggers: + synapse: + level: INFO + handlers: [console, file] + synapse.storage.SQL: + level: WARNING +``` -- `host`: Hostname or IP address of the log aggregator. -- `port`: Numerical port to contact on the host. \ No newline at end of file +The new logging configuration is a bit more verbose, but significantly more +flexible. It allows for configuration that were not previously possible, such as +sending plain logs over the network, or using different handlers for different +modules. |