Graphite - allow to silently skip infinity and NaN values

[piotrp]

Feature Request

Allow Graphite parser to silently ignore values that are supported by Graphite but unsupported by InfluxDB (NaN, infinity).

Proposal:

Introduce a flag that would allow to drop these values without writing anything to log.

Current behavior:

Parser logs an error after encountering such value:

telegraf/plugins/parsers/graphite/parser.go

Lines 124 to 126 in 3f03fa6

	if math.IsNaN(v) || math.IsInf(v, 0) {
	return nil, &UnsupposedValueError{Field: fields[0], Value: v}
	}

Desired behavior:

Silently drop infinity and NaN values (Inf, -Inf, NaN, Infinity, -Infinity). They are already properly parsed, but currently log an error.

Use case:

I want to process some Graphite metrics in Telegraf and pass them to InfluxDB, but currently Telegraf generates an error message to system journal for each dropped metric value, resulting in an unacceptable amount of logs.