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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>
57 lines
2.2 KiB
Go
57 lines
2.2 KiB
Go
// Copyright (c) 2017 Uber Technologies, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package jaeger
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import (
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opentracing "github.com/opentracing/opentracing-go"
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)
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// ContribObserver can be registered with the Tracer to receive notifications
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// about new Spans. Modelled after github.com/opentracing-contrib/go-observer.
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type ContribObserver interface {
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// Create and return a span observer. Called when a span starts.
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// If the Observer is not interested in the given span, it must return (nil, false).
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// E.g :
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// func StartSpan(opName string, opts ...opentracing.StartSpanOption) {
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// var sp opentracing.Span
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// sso := opentracing.StartSpanOptions{}
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// if spanObserver, ok := Observer.OnStartSpan(span, opName, sso); ok {
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// // we have a valid SpanObserver
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// }
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// ...
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// }
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OnStartSpan(sp opentracing.Span, operationName string, options opentracing.StartSpanOptions) (ContribSpanObserver, bool)
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}
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// ContribSpanObserver is created by the Observer and receives notifications
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// about other Span events. This interface is meant to match
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// github.com/opentracing-contrib/go-observer, via duck typing, without
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// directly importing the go-observer package.
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type ContribSpanObserver interface {
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OnSetOperationName(operationName string)
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OnSetTag(key string, value interface{})
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OnFinish(options opentracing.FinishOptions)
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}
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// wrapper observer for the old observers (see observer.go)
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type oldObserver struct {
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obs Observer
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}
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func (o *oldObserver) OnStartSpan(sp opentracing.Span, operationName string, options opentracing.StartSpanOptions) (ContribSpanObserver, bool) {
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spanObserver := o.obs.OnStartSpan(operationName, options)
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return spanObserver, spanObserver != nil
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}
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