lb_Docker_cAdvisor

Agent that parses input metrics from cAdvisor https://github.com/google/cadvisor about a Docker service cluster, and then summarizes such input metrics into a single scalar value to implement Dynamic Weighted Round Robin for a LB.

(Another option where to take the input metrics would be to take the metrics from the Docker Engine API directly, https://docs.docker.com/engine/api/v1.21/, -e.g., the query GET /containers/(id or name)/stats-, or to take them from monitoring systems like Prometheus.)

WIP

This project is a work in progress. The implementation is incomplete and subject to change. The documentation can be inaccurate.

How to Run:

Run Maven:

    mvn

By default, it queries the cAdvisor at localhost:8080 address. (In fact, the program accepts the hostname/IP address of the cAdvisor server as the first command-line argument -add this address explicitly in the Maven pom.xml in this project, for the corresponding argument element. To change the port name to query cAdvisor from the default of 8080 also is easily doable in the next argument element in the pom.xml file.)

Notes

cAdvisor returns multiple stats (under the "stats" subtree) for each Docker container, including a timestamp for each complete measure (see the timestamp at the bottom) for it returns multiple sets of measures for each Docker container. An example is below (the JSON from cAdvisor has been very abbreviated):

  {
      "/docker/cfc0fb6f62f9cc35b38d5d8647667739e7efb90e15b4bab869f34682387be0d7": {
          "aliases": [ ... ],
          ...,
          "stats": [    <<<--- note that "stats" is an array
           {
              "cpu": {
                "load_average": 0,
                "usage": {
                    ...,
                    "system": 1410360000000,
                    "total": 2895301641397,
                    "user": 1138870000000
                }
            },
            "diskio": { ... },
            "memory": {
                "cache": 65536,
                ...,
                "max_usage": 84123648,
                "rss": 73531392,
                "swap": 0,
                "usage": 73707520,
                "working_set": 73674752
            },
            "network": { ... },
            ...,
            "timestamp": "2018-10-15T00:02:55.142234734Z"
        },
        ... more complete "stats" samples from cAdvisor about this same
        ... Docker container