Adding unit tests to opentelemetry tracing

Refractor newExporter and newTracer, add unit tests to them
This PR is part of issue 7493

Signed-off-by: Tony Fang <nenghui.fang@gmail.com>

tracing/plugin/otlp.go

@@ -23,6 +23,7 @@ import (
 	"net/url"
 	"time"
 
+	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/tracing"
@@ -63,7 +64,26 @@ func init() {
 		Requires: []plugin.Type{plugin.TracingProcessorPlugin},
 		Config:   &TraceConfig{ServiceName: "containerd", TraceSamplingRatio: 1.0},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			return newTracer(ic)
+			//get TracingProcessorPlugin which is a dependency
+			plugins, err := ic.GetByType(plugin.TracingProcessorPlugin)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get tracing processors: %w", err)
+			}
+			procs := make([]sdktrace.SpanProcessor, 0, len(plugins))
+			for id, pctx := range plugins {
+				p, err := pctx.Instance()
+				if err != nil {
+					if plugin.IsSkipPlugin(err) {
+						log.G(ic.Context).WithError(err).Infof("skipping tracing processor initialization (no tracing plugin)")
+					} else {
+						log.G(ic.Context).WithError(err).Errorf("failed to initialize a tracing processor %q", id)
+					}
+					continue
+				}
+				proc := p.(sdktrace.SpanProcessor)
+				procs = append(procs, proc)
+			}
+			return newTracer(ic.Context, ic.Config.(*TraceConfig), procs)
 		},
 	})
 
@@ -105,7 +125,7 @@ func newExporter(ctx context.Context, cfg *OTLPConfig) (*otlptrace.Exporter, err
 	if cfg.Protocol == "http/protobuf" || cfg.Protocol == "" {
 		u, err := url.Parse(cfg.Endpoint)
 		if err != nil {
-			return nil, fmt.Errorf("OpenTelemetry endpoint %q is invalid: %w", cfg.Endpoint, err)
+			return nil, fmt.Errorf("OpenTelemetry endpoint %q %w : %v", cfg.Endpoint, errdefs.ErrInvalidArgument, err)
 		}
 		opts := []otlptracehttp.Option{
 			otlptracehttp.WithEndpoint(u.Host),
@@ -124,7 +144,7 @@ func newExporter(ctx context.Context, cfg *OTLPConfig) (*otlptrace.Exporter, err
 		return otlptracegrpc.New(ctx, opts...)
 	} else {
 		// Other protocols such as "http/json" are not supported.
-		return nil, fmt.Errorf("OpenTelemetry protocol %q is not supported", cfg.Protocol)
+		return nil, fmt.Errorf("OpenTelemetry protocol %q : %w", cfg.Protocol, errdefs.ErrNotImplemented)
 	}
 }
 
@@ -132,9 +152,7 @@ func newExporter(ctx context.Context, cfg *OTLPConfig) (*otlptrace.Exporter, err
 // its sampling ratio and returns io.Closer.
 //
 // Note that this function sets process-wide tracing configuration.
-func newTracer(ic *plugin.InitContext) (io.Closer, error) {
-	ctx := ic.Context
-	config := ic.Config.(*TraceConfig)
+func newTracer(ctx context.Context, config *TraceConfig, procs []sdktrace.SpanProcessor) (io.Closer, error) {
 
 	res, err := resource.New(ctx,
 		resource.WithHost(),
@@ -154,25 +172,8 @@ func newTracer(ic *plugin.InitContext) (io.Closer, error) {
 		sdktrace.WithResource(res),
 	}
 
-	ls, err := ic.GetByType(plugin.TracingProcessorPlugin)
-	if err != nil {
-		return nil, fmt.Errorf("failed to get tracing processors: %w", err)
-	}
-
-	procs := make([]sdktrace.SpanProcessor, 0, len(ls))
-	for id, pctx := range ls {
-		p, err := pctx.Instance()
-		if err != nil {
-			if plugin.IsSkipPlugin(err) {
-				log.G(ctx).WithError(err).Infof("skipping tracing processor initialization (no tracing plugin)")
-			} else {
-				log.G(ctx).WithError(err).Errorf("failed to initialize a tracing processor %q", id)
-			}
-			continue
-		}
-		proc := p.(sdktrace.SpanProcessor)
+	for _, proc := range procs {
 		opts = append(opts, sdktrace.WithSpanProcessor(proc))
-		procs = append(procs, proc)
 	}
 
 	provider := sdktrace.NewTracerProvider(opts...)
@@ -189,6 +190,7 @@ func newTracer(ic *plugin.InitContext) (io.Closer, error) {
 		}
 		return nil
 	}}, nil
+
 }
 
 // Returns a composite TestMap propagator

tracing/plugin/otlp_test.go

@@ -0,0 +1,118 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package plugin
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/containerd/containerd/errdefs"
+	"go.opentelemetry.io/otel/sdk/trace"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+)
+
+// TestNewExporter runs tests with different combinations of configuration for NewExporter function
+func TestNewExporter(t *testing.T) {
+
+	for _, testcase := range []struct {
+		name   string
+		input  OTLPConfig
+		output error
+	}{
+		{
+			name: "Test http/protobuf protocol, expect no error",
+			input: OTLPConfig{Endpoint: "http://localhost:4318",
+				Protocol: "http/protobuf",
+				Insecure: false},
+			output: nil,
+		},
+		{
+			name: "Test invalid endpoint, expect ErrInvalidArgument error",
+			input: OTLPConfig{Endpoint: "http://localhost\n:4318",
+				Protocol: "http/protobuf",
+				Insecure: false},
+			output: errdefs.ErrInvalidArgument,
+		},
+		{
+			name: "Test default protocol, expect no error",
+			input: OTLPConfig{Endpoint: "http://localhost:4318",
+				Protocol: "",
+				Insecure: false},
+			output: nil,
+		},
+		{
+			name: "Test grpc protocol, expect no error",
+			input: OTLPConfig{Endpoint: "http://localhost:4317",
+				Protocol: "grpc",
+				Insecure: false},
+			output: nil,
+		},
+		{
+			name: "Test http/json protocol which is not supported, expect not implemented error",
+			input: OTLPConfig{Endpoint: "http://localhost:4318",
+				Protocol: "http/json",
+				Insecure: false},
+			output: errdefs.ErrNotImplemented,
+		},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			t.Logf("input: %v", testcase.input)
+
+			ctx := context.TODO()
+			exp, err := newExporter(ctx, &testcase.input)
+			t.Logf("output: %v", err)
+
+			if err == nil {
+				if err != testcase.output {
+					t.Fatalf("Expect to get error: %v, however no error got\n", testcase.output)
+				} else if exp == nil {
+					t.Fatalf("Something went wrong, Exporter not created as expected\n")
+				}
+			} else {
+				if !errors.Is(err, testcase.output) {
+					t.Fatalf("Expect to get error: %v, however error %v returned\n", testcase.output, err)
+				}
+			}
+
+		})
+	}
+}
+
+// TestNewTracer runs test for NewTracer function
+func TestNewTracer(t *testing.T) {
+
+	config := &TraceConfig{ServiceName: "containerd", TraceSamplingRatio: 1.0}
+	t.Logf("config: %v", config)
+
+	procs := make([]sdktrace.SpanProcessor, 0, 1)
+
+	//Create a dummy in memory exporter for test
+	exp := tracetest.NewInMemoryExporter()
+	proc := trace.NewBatchSpanProcessor(exp)
+
+	procs = append(procs, proc)
+
+	ctx := context.TODO()
+	tracerCloser, err := newTracer(ctx, config, procs)
+	if err != nil {
+		t.Fatalf("Something went wrong, Tracer not created as expected\n")
+	}
+
+	defer tracerCloser.Close()
+}