[Bugfix] Fix JMX merging logic to append multiple jvm configurations

[lisguo]

Description of the issue

Currently if you try to use the "append-config" action on two configurations that have separate JVM configurations, it will fail.

Kafka Config:

{
  "metrics": {
    "namespace": "CWAgent",
    "metrics_collected": {
      "jmx": [
        {
          "endpoint": "localhost:1111",
          "kafka": {
            "measurement": [
              "kafka.request.time.avg",
            ]
          },
          "append_dimensions": {
            "ClusterName": "MyKafkaCluster"
          }
        },
        {
          "endpoint": "localhost:1111",
          "jvm": {
            "measurement": [
              "jvm.classes.loaded",
            ]
          },
          "append_dimensions": {
            "ProcessGroupName": "MyKafkaCluster"
          }
        }
      ]
    }
  }
}

Tomcat config:

{
  "metrics": {
    "namespace": "CWAgent",
    "metrics_collected": {
      "jmx": [
        {
          "endpoint": "localhost:2222",
          "tomcat": {
            "measurement": [
              "tomcat.sessions",
            ]
          },
          "append_dimensions": {
            "AppName": "MyTomcatServer"
          }
        },
        {
          "endpoint": "localhost:2222",
          "jvm": {
            "measurement": [
              "jvm.classes.loaded",
            ]
          },
          "append_dimensions": {
            "ProcessGroupName": "MyTomcatServer"
          }
        }
      ]
    }
  }
}

I expect this to merge the jvm configurations to this valid config:

{
  "metrics": {
    "namespace": "CWAgent",
    "metrics_collected": {
      "jmx": [
        {
          "endpoint": "localhost:1111",
          "kafka": {
            "measurement": [
              "kafka.request.time.avg",
            ]
          },
          "append_dimensions": {
            "ClusterName": "MyKafkaCluster"
          }
        },
        {
          "endpoint": "localhost:1111",
          "jvm": {
            "measurement": [
              "jvm.classes.loaded",
            ]
          },
          "append_dimensions": {
            "ProcessGroupName": "MyKafkaCluster"
          }
        },
        {
          "endpoint": "localhost:2222",
          "tomcat": {
            "measurement": [
              "tomcat.sessions",
            ]
          },
          "append_dimensions": {
            "AppName": "MyTomcatServer"
          }
        },
        {
          "endpoint": "localhost:2222",
          "jvm": {
            "measurement": [
              "jvm.classes.loaded",
            ]
          },
          "append_dimensions": {
            "ProcessGroupName": "MyTomcatServer"
          }
        }
      ]
    }
  }
}

Description of changes

Modify the mergeMap function in the translator to add a conditional if we see a "jmx" configuration, then merge the incoming jmx config into the list.

License

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Tests

Added unit test and manual testing. I appended 4 jmx configurations and see the otel receivers populated:

receivers:
    jmx/0:
        collection_interval: 1m0s
        endpoint: localhost:1111
        jar_path: /opt/aws/amazon-cloudwatch-agent/bin/opentelemetry-jmx-metrics.jar
        otlp:
            endpoint: 0.0.0.0:0
            timeout: 5s
        resource_attributes:
            ProcessGroupName: CinchJVM
        target_system: jvm
    jmx/1:
        collection_interval: 1m0s
        endpoint: localhost:2222
        jar_path: /opt/aws/amazon-cloudwatch-agent/bin/opentelemetry-jmx-metrics.jar
        otlp:
            endpoint: 0.0.0.0:0
            timeout: 5s
        resource_attributes:
            ClusterName: MyKafkaCluster
        target_system: kafka
    jmx/2:
        collection_interval: 1m0s
        endpoint: localhost:2222
        jar_path: /opt/aws/amazon-cloudwatch-agent/bin/opentelemetry-jmx-metrics.jar
        otlp:
            endpoint: 0.0.0.0:0
            timeout: 5s
        resource_attributes:
            ProcessGroupName: MyKafkaCluster
        target_system: jvm
    jmx/3:
        collection_interval: 1m0s
        endpoint: localhost:3333
        jar_path: /opt/aws/amazon-cloudwatch-agent/bin/opentelemetry-jmx-metrics.jar
        otlp:
            endpoint: 0.0.0.0:0
            timeout: 5s
        resource_attributes:
            AppName: MyTomcatServer
        target_system: tomcat
    jmx/4:
        collection_interval: 1m0s
        endpoint: localhost:3333
        jar_path: /opt/aws/amazon-cloudwatch-agent/bin/opentelemetry-jmx-metrics.jar
        otlp:
            endpoint: 0.0.0.0:0
            timeout: 5s
        resource_attributes:
            ProcessGroupName: MyTomcatServer
        target_system: jvm

Requirements

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1. Run make fmt and make fmt-sh
2. Run make lint

---

Integration Tests

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[musa-asad]

Can we make this more general? Can we verify if we're looking at a list and then attempt to merge the list instead of specifying "jmx" specifically?

[JayPolanco]

But then how would the append-config look when objects are used instead of an array?

[musa-asad]

I think we can have two cases: 1) two arrays and 2) an array and an object. We could set up two conditions that check for each case and we can implement logic to merge an array and an object together (if we don't have that.)

[lisguo]

added an allowlist, not sure the best way to detect the case where we are merging two jmx objects and turn it into an array.

Right now I have it so that we have multiple different cases:

1. Merging two jvm sections which are maps, if both are identical we only have a single configuration
2. Merge two jvm sections which are maps, they are not identical -> have an array with two jvm objects
3. Merge one jvm section that is an array with a map that are not identical -> two jvm objects in an array
4. Merge two jvm sections which are arrays, they are not identical -> two jvm objects in array
5. Merge two jvm sections which are arrays, they are identical -> an array with a single object