Remote Sampling - XRay (Part 1) (Fetching Sampling Rules)

samplers/aws/go.mod

@@ -3,8 +3,8 @@ module go.opentelemetry.io/contrib/samplers/aws
 go 1.16
 
 require (
-	github.com/go-logr/logr v1.2.1 // indirect
-	github.com/go-logr/stdr v1.2.0 // indirect
+	github.com/go-logr/logr v1.2.1
+	github.com/go-logr/stdr v1.2.0
 	github.com/stretchr/testify v1.7.0
 	go.opentelemetry.io/otel/sdk v1.3.0
 )

samplers/aws/xray/client.go

@@ -15,65 +15,52 @@
 package xray
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"net/url"
 )
 
 type xrayClient struct {
 	// http client for sending unsigned proxied requests to the collector
 	httpClient *http.Client
 
-	endpoint string
+	endpoint *url.URL
 }
 
-// newClient returns a http client with proxy endpoint
+// newClient returns an HTTP client with proxy endpoint
 func newClient(d string) *xrayClient {
 	endpoint := "http://" + d
 
+	endpointURL, err := url.Parse(endpoint)
+	if err != nil {
+		globalLogger.Error(err, "unable to parse endpoint from string")
+	}
+
 	return &xrayClient{
 		httpClient: &http.Client{},
-		endpoint:   endpoint,
+		endpoint:   endpointURL,
 	}
 }
 
 // getSamplingRules calls the collector(aws proxy enabled) for sampling rules
 func (p *xrayClient) getSamplingRules(ctx context.Context) (*getSamplingRulesOutput, error) {
-	rulesInput := getSamplingRulesInput{}
-
-	statisticsByte, _ := json.Marshal(rulesInput)
-	body := bytes.NewReader(statisticsByte)
-
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost, p.endpoint+"/GetSamplingRules", body)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, p.endpoint.String()+"/GetSamplingRules", nil)
 	if err != nil {
-		globalLogger.Error(err, "failed to create http request")
 		return nil, fmt.Errorf("xray client: failed to create http request: %w", err)
 	}
 
 	output, err := p.httpClient.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("xray client: unable to retrieve sampling settings: %w", err)
 	}
+	defer output.Body.Close()
 
-	buf := new(bytes.Buffer)
-	_, err = buf.ReadFrom(output.Body)
-	if err != nil {
-		return nil, fmt.Errorf("xray client: unable to read response body: %w", err)
-	}
-
-	// Unmarshalling json data to populate getSamplingTargetsOutput struct
-	var samplingRulesOutput getSamplingRulesOutput
-	err = json.Unmarshal(buf.Bytes(), &samplingRulesOutput)
-	if err != nil {
+	var samplingRulesOutput *getSamplingRulesOutput
+	if err := json.NewDecoder(output.Body).Decode(&samplingRulesOutput); err != nil {
 		return nil, fmt.Errorf("xray client: unable to unmarshal the response body: %w", err)
 	}
 
-	err = output.Body.Close()
-	if err != nil {
-		globalLogger.Error(err, "failed to close http response body")
-	}
-
-	return &samplingRulesOutput, nil
+	return samplingRulesOutput, nil
 }

samplers/aws/xray/client_test.go

@@ -17,25 +17,92 @@ package xray
 import (
 	"context"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
 	"testing"
 )
 
 func TestGetSamplingRules(t *testing.T) {
-	body := "{\"NextToken\":null,\"SamplingRuleRecords\":[{\"CreatedAt\":0.0,\"ModifiedAt\":1.639517389E9,\"SamplingRule\":{\"Attributes\":{},\"FixedRate\":0.5,\"HTTPMethod\":\"*\",\"Host\":\"*\",\"Priority\":10000,\"ReservoirSize\":60,\"ResourceARN\":\"*\",\"RuleARN\":\"arn:aws:xray:us-west-2:836082170990:sampling-rule/Default\",\"RuleName\":\"Default\",\"ServiceName\":\"*\",\"ServiceType\":\"*\",\"URLPath\":\"*\",\"Version\":1}},{\"CreatedAt\":1.637691613E9,\"ModifiedAt\":1.643748669E9,\"SamplingRule\":{\"Attributes\":{},\"FixedRate\":0.09,\"HTTPMethod\":\"GET\",\"Host\":\"*\",\"Priority\":1,\"ReservoirSize\":3,\"ResourceARN\":\"*\",\"RuleARN\":\"arn:aws:xray:us-west-2:836082170990:sampling-rule/test-rule\",\"RuleName\":\"test-rule\",\"ServiceName\":\"test-rule\",\"ServiceType\":\"local\",\"URLPath\":\"/aws-sdk-call\",\"Version\":1}},{\"CreatedAt\":1.639446197E9,\"ModifiedAt\":1.639446197E9,\"SamplingRule\":{\"Attributes\":{},\"FixedRate\":0.09,\"HTTPMethod\":\"*\",\"Host\":\"*\",\"Priority\":100,\"ReservoirSize\":100,\"ResourceARN\":\"*\",\"RuleARN\":\"arn:aws:xray:us-west-2:836082170990:sampling-rule/test-rule-1\",\"RuleName\":\"test-rule-1\",\"ServiceName\":\"*\",\"ServiceType\":\"*\",\"URLPath\":\"*\",\"Version\":1}}]}"
+	body := []byte(`{
+  "NextToken": null,
+  "SamplingRuleRecords": [
+    {
+      "CreatedAt": 0,
+      "ModifiedAt": 1639517389,
+      "SamplingRule": {
+        "Attributes": {},
+        "FixedRate": 0.5,
+        "HTTPMethod": "*",
+        "Host": "*",
+        "Priority": 10000,
+        "ReservoirSize": 60,
+        "ResourceARN": "*",
+        "RuleARN": "arn:aws:xray:us-west-2:xxxxxxx:sampling-rule/Default",
+        "RuleName": "Default",
+        "ServiceName": "*",
+        "ServiceType": "*",
+        "URLPath": "*",
+        "Version": 1
+      }
+    },
+    {
+      "CreatedAt": 1637691613,
+      "ModifiedAt": 1643748669,
+      "SamplingRule": {
+        "Attributes": {},
+        "FixedRate": 0.09,
+        "HTTPMethod": "GET",
+        "Host": "*",
+        "Priority": 1,
+        "ReservoirSize": 3,
+        "ResourceARN": "*",
+        "RuleARN": "arn:aws:xray:us-west-2:xxxxxxx:sampling-rule/test-rule",
+        "RuleName": "test-rule",
+        "ServiceName": "test-rule",
+        "ServiceType": "local",
+        "URLPath": "/aws-sdk-call",
+        "Version": 1
+      }
+    },
+    {
+      "CreatedAt": 1639446197,
+      "ModifiedAt": 1639446197,
+      "SamplingRule": {
+        "Attributes": {},
+        "FixedRate": 0.09,
+        "HTTPMethod": "*",
+        "Host": "*",
+        "Priority": 100,
+        "ReservoirSize": 100,
+        "ResourceARN": "*",
+        "RuleARN": "arn:aws:xray:us-west-2:xxxxxxx:sampling-rule/test-rule-1",
+        "RuleName": "test-rule-1",
+        "ServiceName": "*",
+        "ServiceType": "*",
+        "URLPath": "*",
+        "Version": 1
+      }
+    }
+  ]
+}`)
 	ctx := context.Background()
 
 	// generate a test server so we can capture and inspect the request
 	testServer := httptest.NewServer(http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
-		_, _ = res.Write([]byte(body))
+		_, err := res.Write([]byte(body))
+		require.NoError(t, err)
 	}))
 
-	u, _ := url.Parse(testServer.URL)
+	u, err := url.Parse(testServer.URL)
+	require.NoError(t, err)
+
 	client := newClient(u.Host)
 
-	samplingRules, _ := client.getSamplingRules(ctx)
+	samplingRules, err := client.getSamplingRules(ctx)
+	require.NoError(t, err)
+
 	assert.Equal(t, *samplingRules.SamplingRuleRecords[0].SamplingRule.RuleName, "Default")
 	assert.Equal(t, *samplingRules.SamplingRuleRecords[0].SamplingRule.ServiceType, "*")
 	assert.Equal(t, *samplingRules.SamplingRuleRecords[0].SamplingRule.Host, "*")
@@ -57,3 +124,56 @@ func TestGetSamplingRules(t *testing.T) {
 	assert.Equal(t, *samplingRules.SamplingRuleRecords[2].SamplingRule.ReservoirSize, int64(100))
 	assert.Equal(t, *samplingRules.SamplingRuleRecords[2].SamplingRule.FixedRate, 0.09)
 }
+
+func TestGetSamplingRulesWithMissingValues(t *testing.T) {
+	body := []byte(`{
+  "NextToken": null,
+  "SamplingRuleRecords": [
+    {
+      "CreatedAt": 0,
+      "ModifiedAt": 1639517389,
+      "SamplingRule": {
+        "Attributes": {},
+        "FixedRate": 0.5,
+        "HTTPMethod": "*",
+        "Host": "*",
+        "ResourceARN": "*",
+        "RuleARN": "arn:aws:xray:us-west-2:xxxxxxx:sampling-rule/Default",
+        "RuleName": "Default",
+        "ServiceName": "*",
+        "ServiceType": "*",
+        "URLPath": "*",
+        "Version": 1
+      }
+    }
+  ]
+}`)
+	ctx := context.Background()
+
+	// generate a test server so we can capture and inspect the request
+	testServer := httptest.NewServer(http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
+		_, err := res.Write([]byte(body))
+		require.NoError(t, err)
+	}))
+
+	u, err := url.Parse(testServer.URL)
+	require.NoError(t, err)
+
+	client := newClient(u.Host)
+
+	samplingRules, err := client.getSamplingRules(ctx)
+	require.NoError(t, err)
+
+	// Priority and ReservoirSize are missing in API response so they are assigned as nil
+	assert.Nil(t, samplingRules.SamplingRuleRecords[0].SamplingRule.Priority)
+	assert.Nil(t, samplingRules.SamplingRuleRecords[0].SamplingRule.ReservoirSize)
+
+	// other values are stored as expected
+	assert.Equal(t, *samplingRules.SamplingRuleRecords[0].SamplingRule.RuleName, "Default")
+}
+
+func TestNewClient(t *testing.T) {
+	xrayClient := newClient("127.0.0.1:2020")
+
+	assert.Equal(t, xrayClient.endpoint.String(), "http://127.0.0.1:2020")
+}

samplers/aws/xray/clock.go

@@ -18,15 +18,15 @@ import (
 	"time"
 )
 
-// Clock provides an interface to implement method for getting current time.
-type Clock interface {
-	Now() time.Time
+// clock provides an interface to implement method for getting current time.
+type clock interface {
+	now() time.Time
 }
 
-// DefaultClock is an implementation of Clock interface.
-type DefaultClock struct{}
+// defaultClock is an implementation of Clock interface.
+type defaultClock struct{}
 
-// Now returns current time.
-func (t *DefaultClock) Now() time.Time {
+// now returns current time.
+func (t *defaultClock) now() time.Time {
 	return time.Now()
 }

samplers/aws/xray/rand.go

@@ -91,24 +91,24 @@ type Rand interface {
 
 // DefaultRand is an implementation of Rand interface.
 // It is safe for concurrent use by multiple goroutines.
-type DefaultRand struct{}
+type defaultRand struct{}
 
 var globalRand = newGlobalRand()
 
 // Int63n returns, as an int64, a non-negative pseudo-random number in [0,n)
 // from the default Source.
-func (r *DefaultRand) Int63n(n int64) int64 {
+func (r *defaultRand) Int63n(n int64) int64 {
 	return globalRand.Int63n(n)
 }
 
 // Intn returns, as an int, a non-negative pseudo-random number in [0,n)
 // from the default Source.
-func (r *DefaultRand) Intn(n int) int {
+func (r *defaultRand) Intn(n int) int {
 	return globalRand.Intn(n)
 }
 
 // Float64 returns, as a float64, a pseudo-random number in [0.0,1.0)
 // from the default Source.
-func (r *DefaultRand) Float64() float64 {
+func (r *defaultRand) Float64() float64 {
 	return globalRand.Float64()
 }