feat: added option for custom logging (Teku only)

[lucassaldanha]

What/Why

The idea here is to bypass the global logging configuration, inject a log4j.xml directly into the container, and use it in Teku for fine-grained logging control.

One recent use case is during the implementation of partial messages, which requires changes to libp2p. Even during startup, we need to see TRACE messages from libp2p, but if we set the level to trace globally, or even just for the node, the amount of logging generated is absurd. Using a custom log4j.xml file, we were able to selectively enable TRACE messages for specific classes or packages.

Implementation details

• Introduced a new option to participant called custom_log_config.
• When custom_log_config is not set, or is false, we default to the standard behaviour, setting --logging and --log-destination;
• When custom_log_config is true, we set -log-destination=CUSTOM what makes Teku skip any particular log configuration and expects a log4j configuration file.
• It is up to the user to provide the correct configuration, the easiest way is to use an environment variable (refer to example).

Example

Here is an example of what the config would look like for Teku using a custom log4j.xml file:

extra_files:
  log4j.xml: |
    <?xml version="1.0" encoding="UTF-8"?>
    <Configuration status="INFO">
      <Properties>
        <Property name="root.log.level">INFO</Property>
      </Properties>

      <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
          <PatternLayout
            pattern="%d{yyyy-MM-dd HH:mm:ss.SSSZZZ} | %t | %-5level | %c{1} | %msg %throwable%n" />
        </Console>
      </Appenders>

      <Loggers>
        <Logger name="io.libp2p.pubsub.gossip" level="TRACE" additivity="false">
          <AppenderRef ref="Console" />
        </Logger>

        <Root level="${sys:root.log.level}">
          <AppenderRef ref="Console" />
        </Root>
      </Loggers>
    </Configuration>

participants_matrix:
  el:
    - el_type: geth
      el_image: ethpandaops/geth:master
  cl:
    - cl_type: teku
      cl_image: ethpandaops/teku:master
      custom_log_config: true
      cl_extra_mounts:
        "/configs": "log4j.xml" #File available at: /configs/log4j.xml
      cl_extra_env_vars:
        LOG4J_CONFIGURATION_FILE: "/configs/log4j.xml" 
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