@cumulus/logger

# @cumulus/logger > A logging library for use on the Cumulus project. The `@cumulus/logger` library exports a `Logger` class, which generates JSON-formated log events. Log events always have the following keys: - **level** (string) - the priority level of the message - **message** (string) - the message itself - **sender** (string) - the resource that created the message - **timestamp** (string) - an ISO-8601 timestamp Log events may have the following options keys: - **executions** (string) - **granules** (string [stringified array of objects]) - **parentArn** (string) - **stackName** (string) - **version** (string) - **asyncOperationId** (string) Log events may also contain user-specified keys. Example log event: ```json { "level": "info", "message": "hello world", "sender": "greetingFunction", "timestamp": "2018-10-19T19:12:47.501Z" } ``` ## Install ```bash npm install @cumulus/logger ``` ## Usage ```js const Logger = require('@cumulus/logger'); const log = new Logger({ sender: 'example' }); log.info('hello, world'); ``` ## API ### `new Logger({ [asyncOperationId], [executions], [granules], [parentArn], [sender], [stackName], [version] })` #### asyncOperationId Type: `string` An optional async operation id associated with a workflow. #### executions Type: `string` An optional description of the executions. #### granules type: `string` An optional granules string. Generally a stringified array of granule objects. #### parentArn type: `string` An optional stepfunction ARN of the parent workflow that triggered the current execution. #### sender Type: `string` The sender of the log event. Typically a Lambda Function Name or ECS Task Name. Defaults to "unknown". #### stackName type: `string` Cumulus stack name. #### version Type: `string` An optional version. ### `log.debug([...messageArgs])` Writes a log event to stdout with level set to "debug". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ### `log.error([...messageArgs][, error])` Writes a log event to stderr with level set to "error". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). #### error Type: `Error` If the last argument is an Error then the following additional properties will be set on the log event: - **error** (Object) - **name** (string) - **message** (string) - **stack** (Array\<string\>) - the lines of the stack trace ### `log.fatal([...messageArgs])` Writes a log event to stdout with level set to "fatal". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ### `log.info([...messageArgs])` Writes a log event to stdout with level set to "info". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ### `log.infoWithAdditionalKeys(additionalKeys, ...messageArgs)` Writes a log event to stdout with level set to "info". In addition to the standard keys, additional keys will be added to the event. If an additional key is specified with the same name as a standard key, the value standard key will be displayed. #### additionalKeys Type: `Object` Additional key/value pairs to be added to the event. #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ### `log.trace([...messageArgs])` Writes a log event to stdout with level set to "trace". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ### `log.warn([...messageArgs])` Writes a log event to stdout with level set to "debug". #### args Type: `...any` See [console.log()](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args). ## About Cumulus Cumulus is a cloud-based data ingest, archive, distribution and management prototype for NASA's future Earth science data streams. [Cumulus Documentation](https://nasa.github.io/cumulus) ## Contributing To make a contribution, please [see our contributing guidelines](https://github.com/nasa/cumulus/blob/master/CONTRIBUTING.md).