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author | Kim Alvefur <zash@zash.se> |
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date | Thu, 17 Aug 2023 08:34:17 +0200 (16 months ago) |
parents | 893b9c3c0d20 |
children | 133b23758cf6 |
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--- labels: - 'Stage-Beta' summary: 'Log to in-memory ringbuffer' ... Introduction ============ Sometimes debug logs are too verbose for continuous logging to disk. However occasionally you may be interested in the debug logs when a certain event occurs. This module allows you to store all logs in a fixed-size buffer in Prosody's memory, and dump them to a file whenever you want. # Configuration First of all, you need to load the module by adding it to your global `modules_enabled`: ``` {.lua} modules_enabled = { ... "log_ringbuffer"; ... } ``` By default the module will do nothing - you need to configure a log sink, using Prosody's usual [logging configuration](https://prosody.im/doc/advanced_logging). ``` {.lua} log = { -- Log errors to a file error = "/var/log/prosody/prosody.err"; -- Log debug and higher to a 2MB buffer { to = "ringbuffer", size = 1024*1024*2, filename_template = "debug-logs-{pid}-{count}.log", signal = "SIGUSR2" }; } ``` The possible fields of the logging config entry are: `to` : Set this to `"ringbuffer"`. `levels` : The log levels to capture, e.g. `{ min = "debug" }`. By default, all levels are captured. `size` : The size, in bytes, of the buffer. When the buffer fills, old data will be overwritten by new data. `lines` : If specified, preserves the latest N complete lines in the buffer. The `size` option is ignored when this option is set. `filename` : The name of the file to dump logs to when triggered. `filename_template` : This parameter may optionally be specified instead of `filename. It may contain a number of variables, described below. Defaults to `"{paths.data}/ringbuffer-logs-{pid}-{count}.log"`. Only one of the following triggers may be specified: `signal` : A signal that will cause the buffer to be dumped, e.g. `"SIGUSR2"`. Do not use any signal that is used by any other Prosody module, to avoid conflicts. `event` : Alternatively, the name of a Prosody global event that will trigger the logs to be dumped, e.g. `"config-reloaded"`. ## Filename variables If `filename_template` is specified instead of `filename`, it may contain any of the following variables in curly braces, e.g. `{pid}`. `pid` : The PID of the current process `count` : A counter that begins at 0 and increments for each dump made by the current process. `time` : The unix timestamp at which the dump is made. It can be formatted to human-readable local time using `{time|yyyymmdd}` and `{time|hhmmss}`. `paths` : Allows access to Prosody's known filesystem paths, use e.g. `{paths.data}` for the path to Prosody's data directory. The filename does not have to be unique for every dump - if a file with the same name already exists, it will be appended to. ## Integration with mod_debug_traceback This module can be used in combination with [mod_debug_traceback] so that debug logs are dumped at the same time as the traceback. Use the following configuration: ``` {.lua} log = { --- -- other optional logging config here -- --- { to = "ringbuffer"; filename_template = "{paths.data}/traceback-{pid}-{count}.log"; event = "debug_traceback/triggered"; }; } ``` If the filename template matches the traceback path, both logs and traceback will be combined into the same file. Of course separate files can be specified if preferred. # Compatibility 0.11 and later.