Make metrictank/publish/kafka instantiable with parameters

[D3luxee]

Hi @Dieterbe ,
i've started to look into grafana/carbon-relay-ng#442 and the first issue i've found was that the publisher is configured via flags.
carbon-relay-ng has to instantiate multiple instances of the publisher (one per route) with different configs, since flags are globally this is no option here.

I would suggest to implement a second "New" function which allows passing the parameters:

func NewWithOptions(brokers []string, topic, codecOption, partitionSchemes, schemaFile, kafkaVersionString string, onlyOrgIdsOption []int64, flushFrequency, clearInterval time.Duration, producerMaxMessages int, useV2, encodeOrgID, autoInterval bool) *mtPublisher {
	enabled = true                         // enable metric publishing
	topicsStr = topic                      // set topic
	onlyOrgIds = onlyOrgIdsOption          // restrict publishing data belonging to org id; 0 means no restriction (may be given multiple times, once per topic specified in 'metrics-topic', as a comma-separated list)
	codec = codecOption                    // "compression: none|gzip|snappy"
	partitionSchemesStr = partitionSchemes // method used for partitioning metrics. (byOrg|bySeries|bySeriesWithTags|bySeriesWithTagsFnv) (may be given multiple times, once per topic, as a comma-separated list)
	flushFreq = flushFrequency             // The best-effort frequency of flushes to kafka
	maxMessages = producerMaxMessages      // The maximum number of messages the producer will send in a single request
	schemasConf = schemaFile               // path to carbon storage-schemas.conf file
	v2 = useV2                             // enable optimized MetricPoint payload
	v2Org = encodeOrgID                    // encode org-id in messages
	v2ClearInterval = clearInterval        // interval after which we always resend a full MetricData
	kafkaVersionStr = kafkaVersionString   // Kafka version in semver format. All brokers must be this version or newer.
	return New(brokers, autoInterval)
}

https://github.com/grafana/metrictank/blob/master/publish/kafka/publish.go

What is your opinion on this?

[Dieterbe]

have a look at some of the other plugins, for example store/cassandra/config.go. note how it has a config struct, you can create a cliconfig and register flags on it, but also build a config however you like (e.g. externally)

[stale]

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