Add native support for modifying the log level programmatically at runtime

[daneshk]

Summary

We need a new Java API to change the log level programmatically at runtime without restarting the application. At the moment, the only way of changing the log level is from the Config.toml file that needs to restart the application. We need a new API to change the level programmatically.

[daneshk]

Related issue: #4633

[daneshk]

The proposed native API

  /**
   * Set the log level dynamically globally or for a specific module.
   * This is a native implementation of the setLogLevel function in the log-api module.
   * 
   * @param logLevel   The log level to be set
   * @param packageName The package name of the module
   * @param moduleName  The module name
   */
  public static void setLogLevel(Environment env, String logLevel, String packageName, String moduleName);

This log level change is applied temporary for the running instance and it is not persisted. It resets after restarting the instance.

[daneshk]

This support needs calling the ballerina util method from the Java side. This support is addressed in the issue[1]

1. [New Feature]: Runtime API to start the new Runtime and call ballerina function ballerina-lang#42128

[daneshk]

This task is deprioritized because the initial control plan version will not support changing log levels in Ballerina nodes. So we are not going to ship this support in update 09. Move this issue onto hold till we get the requirement.

[daneshk]

We(@anuruddhal, @warunalakshitha, @ThisaruGuruge, @TharmiganK and me) discussed how to support dynamically changing log levels at runtime. Here’s a summary of our conclusions:

1. We will enable the ability to change log levels via ICP.
2. This feature will be included in the next ICP release, scheduled for the end of March. The Alpha pack will be ready by the end of February.
3. Initially, we will only support changing the log level for the root logger. Users will not be able to change log levels dynamically for custom loggers, as defined in [1].
4. If users have defined any module-level log configurations in the Config.toml file [2], those modules will also be listed under the root logger in ICP, allowing users to change the log level for those specific modules.
5. From the log module level, we will be providing two native APIs to be utilized by the ICP
   • Get current log levels
   • Update the log level

https://ballerina.io/learn/by-example/custom-logger/
https://ballerina.io/learn/by-example/logging-configuration/

[daneshk]

We will provide two Java APIs from the log module for use in the ICP agent, enabling it to function as a service API. The ICP dashboard will call these APIs to retrieve the list of loggers and the modules configured in the application. Additionally, ICP will support adding new module entries with updated log level configurations. Users will have the ability to:

Can Do:

• Remove specific module-level log configurations.
• Add new module-level log configurations.
• Update the log levels for a module.
• Adjust the global root logger's log levels.
• Modify custom loggers created by passing new configurations to the fromConfig API.

Can't Do:

• Users cannot change the log level configurations for custom loggers created from scratch using the logger interface.

From the log package, we will provide the necessary Java APIs for the agent to use.