ECS-based logging for Java applications

Centralized logging for Java applications with the Elastic stack made easy

What is ECS?

Elastic Common Schema (ECS) defines a common set of fields for ingesting data into Elasticsearch. For more information about ECS, visit the ECS Reference Documentation.

What is ECS logging?

This library helps to log ECS-compatible JSON into a file

Example:

{"@timestamp":"2019-08-06T12:09:12.375Z", "log.level": "INFO", "message":"Tomcat started on port(s): 8080 (http) with context path ''", "service.name":"spring-petclinic","process.thread.name":"restartedMain","log.logger":"org.springframework.boot.web.embedded.tomcat.TomcatWebServer"}
{"@timestamp":"2019-08-06T12:09:12.379Z", "log.level": "INFO", "message":"Started PetClinicApplication in 7.095 seconds (JVM running for 9.082)", "service.name":"spring-petclinic","process.thread.name":"restartedMain","log.logger":"org.springframework.samples.petclinic.PetClinicApplication"}
{"@timestamp":"2019-08-06T14:08:40.199Z", "log.level":"DEBUG", "message":"init find form", "service.name":"spring-petclinic","process.thread.name":"http-nio-8080-exec-8","log.logger":"org.springframework.samples.petclinic.owner.OwnerController","transaction.id":"28b7fb8d5aba51f1","trace.id":"2869b25b5469590610fea49ac04af7da"}

Why ECS logging?

Logging in ECS-compatible JSON has the advantage that you don't need to set up a logstash/ingest node pipeline to parse logs using grok. Another benefit is that you are automatically using the field names the Logs UI expects, which means that getting started with it is straightforward.

APM Log correlation

If you are using the Elastic APM Java agent, you can leverage the log correlation feature without any additional configuration.

This lets you jump from the Span timeline in the APM UI to the Logs UI, showing only the logs which belong to the corresponding request. Vice versa, you can also jump from a log line in the Logs UI to the Span Timeline of the APM UI.

Advantages

• No external dependencies
• Highly efficient by manually serializing JSON
• Low/Zero allocations (reduces GC pauses)
  The log4j2 EcsLayout does not allocate any memory (unless the log event contains an Exception)
• No parsing of the log file required
• Decently human-readable JSON structure
  The first three fields are always @timestamp, log.level and message.
• Use the Kibana Logs UI without additional configuration
  As this library adheres to ECS, the Logs UI knows which fields to show

Additional advantages when using in combination with Filebeat

We recommend using this library to log into a JSON log file and let Filebeat send the logs to Elasticsearch

• Resilient in case of outages
  Guaranteed at-least-once delivery without buffering within the application, thus no risk of OutOfMemoryErrors or lost events. There's also the option to use either the JSON logs or plain-text logs as a fallback.
• Loose coupling
  The application does not need to know the details of the logging backend (URI, credentials, etc.). You can also leverage alternative Filebeat outputs, like Logstash, Kafka or Redis.
• Index Lifecycle management
  Leverage Filebeat's default index lifemanagement settings. This is much more efficient than using daily indices.
• Efficient Elasticsearch mappings
  Leverage Filebeat's default ECS-compatible index template

Getting Started

Logging configuration

• Logback
• Log4j2
• Log4j

Filebeat configuration

With filebeat.yml configuration file

filebeat.inputs:
- type: log
  paths: /path/to/logs.json
  json.keys_under_root: true

# no further processing required, logs can directly be sent to Elasticsearch  
output.elasticsearch:
  hosts: ["https://localhost:9200"]
  
# Or to Elastic cloud
# Example:
#cloud.id: "staging:dXMtZWFzdC0xLmF3cy5mb3VuZC5pbyRjZWM2ZjI2MWE3NGJmMjRjZTMzYmI4ODExYjg0Mjk0ZiRjNmMyY2E2ZDA0MjI0OWFmMGNjN2Q3YTllOTYyNTc0Mw=="
#cloud.auth: "elastic:YOUR_PASSWORD"

For more information, check the Filebeat documentation

With Beats Central Management

• Enroll the beat
  In Kibana, go to Management > Beats > Central Management > Enroll Beats and follow the instructions.
• Add a Filebeat input configuration block
  • Configure the path of the log file(s)
  • Set Other config

    type: log
    json.keys_under_root: true

• Add an Output configuration block
  • Set Output type to Elasticsearch
  • Configure the hosts
  • For secured Elasticsearch deployments (like Elastic cloud) set Username and Password