Centralized Application Logs with the Elastic Stack

This repository dives into five different logging patterns:

Parse: Take the log files of your applications and extract the relevant pieces of information.
Send: Add a log appender to send out your events directly without persisting them to a log file.
Structure: Write your events in a structured file, which you can then centralize.
Containerize: Keep track of short-lived containers and configure their logging correctly.
Orchestrate: Stay on top of your logs even when services are short lived and dynamically allocated on Kubernetes.

Dependencies

Docker (and Docker Compose) to run all the required components of the Elastic Stack (Filebeat, Logstash, Elasticsearch, and Kibana) and the containerized Java application. The application is built in Docker, so you don't need to have Java or Gradle installed locally.

Bring up the Elastic Stack and the monitored application: $ docker compose up
Rerun the Java application to generate more logs: $ docker restart java_app
Rebuild the Java application (for example to apply any code changes): $ docker compose up -d --no-deps --build java_app
Remove the Elastic Stack and its volumes: $ docker compose down -v

Start the demo with $ docker compose up or $ docker compose up --build if you want to rebuild the custom images.
Look at the code — which pattern are we building with log statements here?
Look at Management -> Index Management in Kibana.

How many log events should we have? 40. But we have 42 entries instead. Even though 42 would be the perfect number, here it's not.
See the _grokparsefailure in the tag field. Enable the multiline rules in Filebeat. It should automatically refresh and when you run the application again, it should now only collect 40 events.
Show that this works as expected now and drill down to the errors to see which emoji we are logging.
Copy a log line and parse it with the Grok Debugger in Kibana, for example, with the pattern ^\[%{TIMESTAMP_ISO8601:timestamp}\]%{SPACE}%{LOGLEVEL:level} — show https://github.com/logstash-plugins/logstash-patterns-core/blob/master/patterns/grok-patterns to get started. We can copy the rest of the pattern from logstash.conf.
Point to https://github.com/elastic/ecs for the naming conventions.
Show the Data Visualizer in Machine Learning by uploading the LOG file. The output is actually quite good already, but we are sticking to our manual rules for now.
Find the log statements in Kibana's Discover view for the parse index.
Show the pipeline in Kibana's Monitoring view and the other components in Monitoring.
Create a vertical bar chart visualization on the level field. Further break it down into session.

Show that the logs are missing from the first run, since no connection to Logstash could be established before the Java application shut down in the initial run.
Rerun the application with docker restart java_app and see it works now. And we have already seen the main downside of this approach.
Finally, you would need to rename the fields to match ECS in a Logstash filter.

Run the application and show the data in the structure index.
Show the Logback configuration for JSON, since it is a little more complicated than the others.

Show the metadata we are collecting now.
Point to the ingest pipeline and show how everything is working.
See why we needed the grok failure rule, because of the startup error from sending to Logstash directly.
Filter to down to container.name : "java_app" and point out the hinting that stops the multiline statements from being broken up.
Point out how you could break up the output into two indices — docker-* and docker-java-*.
Show the new Logs UI (adapt the pattern to match the right index).