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https://github.com/aljazceru/kata-containers.git
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3a1bbd0271
Add initial support for opentracing by using the `jaeger` package.
Since opentracing uses the `context` package, add a `context.Context`
as the first parameter to all the functions that we might want to
trace. Trace "spans" (trace points) are then added by extracting the
trace details from the specified context parameter.
Notes:
- Although the tracer is created in `main()`, the "root span"
(aka the first trace point) is not added until `beforeSubcommands()`.
This is by design and is a compromise: by delaying the creation of the
root span, the spans become much more readable since using the web-based
JaegerUI, you will see traces like this:
```
kata-runtime: kata-runtime create
------------ -------------------
^ ^
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Trace name First span name
(which clearly shows the CLI command that was run)
```
Creating the span earlier means it is necessary to expand 'n' spans in
the UI before you get to see the name of the CLI command that was run.
In adding support, this became very tedious, hence my design decision to
defer the creation of the root span until after signal handling has been
setup and after CLI options have been parsed, but still very early in
the code path.
- At this stage, the tracing stops at the `virtcontainers` call
boundary.
- Tracing is "always on" as there doesn't appear to be a way to toggle
it. However, its resolves to a "nop" unless the tracer can talk to a
jaeger agent.
Note that this commit required a bit of rework to `beforeSubcommands()`
to reduce the cyclomatic complexity.
Fixes #557.
Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>
65 lines
2.6 KiB
Go
65 lines
2.6 KiB
Go
package opentracing
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import "github.com/opentracing/opentracing-go/log"
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// A NoopTracer is a trivial, minimum overhead implementation of Tracer
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// for which all operations are no-ops.
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//
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// The primary use of this implementation is in libraries, such as RPC
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// frameworks, that make tracing an optional feature controlled by the
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// end user. A no-op implementation allows said libraries to use it
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// as the default Tracer and to write instrumentation that does
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// not need to keep checking if the tracer instance is nil.
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//
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// For the same reason, the NoopTracer is the default "global" tracer
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// (see GlobalTracer and SetGlobalTracer functions).
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//
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// WARNING: NoopTracer does not support baggage propagation.
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type NoopTracer struct{}
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type noopSpan struct{}
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type noopSpanContext struct{}
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var (
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defaultNoopSpanContext = noopSpanContext{}
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defaultNoopSpan = noopSpan{}
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defaultNoopTracer = NoopTracer{}
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)
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const (
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emptyString = ""
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)
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// noopSpanContext:
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func (n noopSpanContext) ForeachBaggageItem(handler func(k, v string) bool) {}
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// noopSpan:
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func (n noopSpan) Context() SpanContext { return defaultNoopSpanContext }
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func (n noopSpan) SetBaggageItem(key, val string) Span { return defaultNoopSpan }
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func (n noopSpan) BaggageItem(key string) string { return emptyString }
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func (n noopSpan) SetTag(key string, value interface{}) Span { return n }
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func (n noopSpan) LogFields(fields ...log.Field) {}
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func (n noopSpan) LogKV(keyVals ...interface{}) {}
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func (n noopSpan) Finish() {}
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func (n noopSpan) FinishWithOptions(opts FinishOptions) {}
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func (n noopSpan) SetOperationName(operationName string) Span { return n }
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func (n noopSpan) Tracer() Tracer { return defaultNoopTracer }
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func (n noopSpan) LogEvent(event string) {}
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func (n noopSpan) LogEventWithPayload(event string, payload interface{}) {}
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func (n noopSpan) Log(data LogData) {}
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// StartSpan belongs to the Tracer interface.
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func (n NoopTracer) StartSpan(operationName string, opts ...StartSpanOption) Span {
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return defaultNoopSpan
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}
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// Inject belongs to the Tracer interface.
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func (n NoopTracer) Inject(sp SpanContext, format interface{}, carrier interface{}) error {
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return nil
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}
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// Extract belongs to the Tracer interface.
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func (n NoopTracer) Extract(format interface{}, carrier interface{}) (SpanContext, error) {
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return nil, ErrSpanContextNotFound
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}
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