22 lines
1.4 KiB
Markdown
22 lines
1.4 KiB
Markdown
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# Logging structured traces
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In order to have meaningful and useful log traces, you should follow
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some general guidelines described in the [Project Guidelines](http://doc-internal.cartodb.net/platform/guidelines.html#structured-logging).
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In this project there is a specific logger in place that takes care of
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format and context of the traces for you. Take a look at [logger.js](https://github.com/CartoDB/CartoDB-SQL-API/blob/b28835ff56a4b3a98e5273d192d48a81974f5a14/lib/utils/logger.js)
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(NOTE: that file will be moved soon to a common module).
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The logger is instantiated as part of the [server startup process](https://github.com/CartoDB/CartoDB-SQL-API/blob/b28835ff56a4b3a98e5273d192d48a81974f5a14/lib/server.js#L17),
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then passed to middlewares and other client classes.
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There are many examples of how to use the logger to generate traces
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throughout the code. Here are a few of them:
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```
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lib/api/middlewares/log-query.js: logger.info({ sql: ensureMaxQueryLength(res.locals.params.sql) }, 'Input query');
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lib/api/middlewares/profiler.js: logger.info({ stats, duration: stats.response / 1000, duration_ms: stats.response }, 'Request profiling stats');
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lib/batch/batch.js: self.logger.info({ job: job.toJSON() }, 'Batch query job finished');
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lib/services/stream-copy-metrics.js: this.logger.info({ ingestion: logData }, 'Copy to/from query metrics');
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```
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