Trickster instruments Distributed Tracing with OpenTelemetry. We import the OpenTelemetry golang packages to instrument support for tracing.
As OpenTelemetry evolves to support additional exporter formats, we will work to extend Trickster to support those as quickly as possible. We also make a best effort to update our otel package imports to the latest releases, whenever we publish a new Trickster release. You can check the go.mod file to see which release of opentelemetry-go we are is using. In this view, to see which version of otel a specific Trickster release imports, use the branch selector dropdown to switch to the tag corresponding to that version of Trickster.
- Jaeger (via OTLP)
- Zipkin
- Console/Stdout (printed locally by the Trickster process)
Trickster allows the operator to configure multiple tracing configurations, which can be associated into each Backend configuration by name.
The example config has exhaustive examples of configuring Trickster for distributed tracing.
Trickster can insert several spans to the traces that it captures, depending upon the type and cacheability of the inbound client request, as described in the table below.
| Span Name | Observes when Trickster is: |
|---|---|
| request | initially handling the client request by a Backend |
| QueryCache | querying the cache for an object |
| WriteCache | writing an object to the cache |
| DeltaProxyCacheRequest | handling a Time Series-based client request |
| FastForward | making a Fast Forward request for time series data |
| ProxyRequest | communicating with an Origin server to fulfill a client request |
| PrepareFetchReader | preparing a client response from a cached or Origin response |
| CacheRevalidation | revalidating a stale cache object against its Origin |
| FetchObject | retrieving a non-time-series object from an Origin |
Trickster supports adding custom tags to every span via the configuration. Depending upon your preferred tracing backend, these may be referred to as attributes. See the example config for examples of adding custom attributes.
Trickster also supports omitting any tags that Trickster inserts by default. The list of default tags are below. For example on the "request" span, an http.url tag is attached with the current full URL. In deployments where that tag may introduce too much cardinality in your backend trace storage system, you may wish to omit that tag and rely on the more concise path tag. Each tracer config can be provided a string list of tags to omit from traces.
http.url- the full HTTP request URLbackend.namebackend.providercache.namecache.providerrouter.path- request path trimmed to the route match path for the request (e.g.,/api/v1/query), good for aggregating when there are large variations in the full URL path
cache.status- the lookup status of cache query. See the cache status reference for a description of the attribute values.
isRange- is true if the client request includes an HTTPRangeheader
isPCF- is true if the origin is configured for Progressive Collapsed Forwarding