uk-gov-mirror / nationalarchives.tdr-prototype-json-logging

A prototype for demonstrating structured JSON logging in a Scala app

TDR JSON logging prototype

This is a prototype app designed to be run on AWS Lambda. It demonstrates how to configure a Scala application to write JSON-formatted logs.

It was built to help us work out how to save logs on the Transfer Digital Records project.

The application just writes logs at a variety of log levels. Some log messages include exceptions, and some include extra custom fields.

It uses the logstash-logback-encoder to write the logs as JSON. See the logback.xml for the JSON log configuration.

Run the project locally

Run sbt run, or run the LambdaLoggingApp object in IntelliJ.

Run the project on AWS Lambda

• Run sbt assembly, which generates a file at target/scala-2.13/example-lambda-logging.jar
• Create a new Lambda function in AWS which uses the Java runtime
• Upload the jar file to the Lambda
• Create a test event to send to the Lambda - the app doesn't actually use this event, so the contents can be anything. The default 'Hello world' message is fine.
• Send the test event to the Lambda
• Inspect the logs in the CloudWatch log group