cc-metric-collector/pkg/ccMetric/README.md

ClusterCockpit metrics

As described in the ClusterCockpit specifications, the whole ClusterCockpit stack uses metrics in the InfluxDB line protocol format. This is also the input and output format for the ClusterCockpit Metric Collector but internally it uses an extended format while processing, named CCMetric.

It is basically a copy of the InfluxDB line protocol MutableMetric interface with one extension. Besides the tags and fields, it contains a list of meta information (re-using the Tag structure of the original protocol):

type ccMetric struct {
    name   string                 // Measurement name
    meta   map[string]string      // map of meta data tags
    tags   map[string]string      // map of of tags
    fields map[string]interface{} // map of of fields
    tm     time.Time              // timestamp
}

type CCMetric interface {
    ToPoint(metaAsTags map[string]bool) *write.Point  // Generate influxDB point for data type ccMetric
    ToLineProtocol(metaAsTags map[string]bool) string // Generate influxDB line protocol for data type ccMetric
    String() string                                   // Return line-protocol like string

    Name() string        // Get metric name
    SetName(name string) // Set metric name

    Time() time.Time     // Get timestamp
    SetTime(t time.Time) // Set timestamp

    Tags() map[string]string                   // Map of tags
    AddTag(key, value string)                  // Add a tag
    GetTag(key string) (value string, ok bool) // Get a tag by its key
    HasTag(key string) (ok bool)               // Check if a tag key is present
    RemoveTag(key string)                      // Remove a tag by its key

    Meta() map[string]string                    // Map of meta data tags
    AddMeta(key, value string)                  // Add a meta data tag
    GetMeta(key string) (value string, ok bool) // Get a meta data tab addressed by its key
    HasMeta(key string) (ok bool)               // Check if a meta data key is present
    RemoveMeta(key string)                      // Remove a meta data tag by its key

    Fields() map[string]interface{}                   // Map of fields
    AddField(key string, value interface{})           // Add a field
    GetField(key string) (value interface{}, ok bool) // Get a field addressed by its key
    HasField(key string) (ok bool)                    // Check if a field key is present
    RemoveField(key string)                           // Remove a field addressed by its key
}

func New(name string, tags map[string]string, meta map[string]string, fields map[string]interface{}, tm time.Time) (CCMetric, error)
func FromMetric(other CCMetric) CCMetric
func FromInfluxMetric(other lp.Metric) CCMetric

The CCMetric interface provides the same functions as the MutableMetric like {Add, Get, Remove, Has}{Tag, Field} and additionally provides {Add, Get, Remove, Has}Meta.

The InfluxDB protocol creates a new metric with influx.New(name, tags, fields, time) while CCMetric uses ccMetric.New(name, tags, meta, fields, time) where tags and meta are both of type map[string]string.

You can copy a CCMetric with FromMetric(other CCMetric) CCMetric. If you get an influx.Metric from a function, like the line protocol parser, you can use FromInfluxMetric(other influx.Metric) CCMetric to get a CCMetric out of it (see NatsReceiver for an example).

Although the cc-specifications defines that there is only a value field for the metric value, the CCMetric still can have multiple values similar to the InfluxDB line protocol.