only one additional dimension possible?

[smaldon-bjss]

An issue that has come up for me is that I want to send metrics to cloudwatch from many different sources for consumption in grafana later. To filter my metrics and construct sensible dashboards I want labels for categories, call "servergroup" and "environment", and within these categories metrics can also come from multiple instances, so I also want a label for "instance_id".

However I found that when I specified multiple -additional_dimension arguments to the program it would only label my metrics with the last argument specified. I looked at the code.

prometheus-to-cloudwatch/main.go

Line 121 in d28e9f2

var additionalDimensions = map[string]string{}

var additionalDimensions = map[string]string{}
if *additionalDimension != "" {
	key, val := keyValMustParse(*additionalDimension, "-additionalDimension must be formatted as NAME=VALUE")
	additionalDimensions[key] = val
}

var replaceDims = map[string]string{}
if *replaceDimensions != "" {
	kvs := strings.Split(*replaceDimensions, ",")
	if len(kvs) > 0 {
		for _, rd := range kvs {
			key, val := keyValMustParse(rd, "-replaceDimensions must be formatted as NAME=VALUE,...")
			replaceDims[key] = val
		}
	}
}

It looks like an map was used just like with replaceDimensions yet the actual code seems limited to only ever populating that map with at most a single key-value pair. This seems like a disappointing limitation?

Would there be any drawback to changing additional_dimension to additional_dimensions (or adding additional_dimensions for backwards compatibility) and copying the same pattern for parsing it as is already in use for replace_dimensions? It looks at a glance like the rest of the code is already there.

[smaldon-bjss]

#38

Something like this?