Documentation
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Overview ¶
Command telemetrysampler is a reference post-trace sampler plugin that demonstrates well-behaved use of the sdk.HostAware telemetry façade. It implements both sdk.Sampler and sdk.HostAware: the engine calls UseHost once (per group, before the first Decide) and the sampler caches the Host to emit bounded metrics and structured logs from Decide.
Decision logic: keep all traces, but increment a "decisions" counter (with a "verdict" label set to "keep") and emit a sparse Info log so the host's rate-limiter and cardinality cap are exercised in a benign way. The sampler is nil-safe: if UseHost was never called (host is nil) Decide proceeds silently without emitting any telemetry.
Config JSON (from SamplerPlugin.config Struct):
{ "logEvery": 100 }
logEvery controls how many batches are processed between Info log emissions; the default is 100. 0 or a negative value is treated as 100.
Build it as a Go plugin (the leading-underscore directory is intentionally excluded from `go build ./...` and linters, exactly like the reference _example directory, yet remains buildable by explicit path):
CGO_ENABLED=1 go build -buildmode=plugin -trimpath \ -o telemetrysampler.so \ ./test/plugins/_telemetrysampler
Source Files