feat: Add instance-id capability to ensure headers are set (#287)

Author: keelerm84

docs/service_spec.md

@@ -104,6 +104,10 @@ v4 of the event schema originally required a `contextKeys` property on several d
 
 This capability is a superset of `"inline-context"`, as it was introduced afterwards.
 
+#### Capability `"instance-id"`
+
+Supports sending the `X-LaunchDarkly-Instance-Id` header in HTTP requests.
+
 #### Capability `"migrations"`
 
 This means that the SDK supports technology migrations, a feature which allows customers to migrate between data sources using well-defined migration stages.

sdktests/common_tests_instance_id.go

@@ -0,0 +1,101 @@
+package sdktests
+
+import (
+	"time"
+
+	"github.com/launchdarkly/go-sdk-common/v3/ldcontext"
+	"github.com/launchdarkly/go-sdk-common/v3/ldvalue"
+	"github.com/launchdarkly/sdk-test-harness/v2/framework/harness"
+	"github.com/launchdarkly/sdk-test-harness/v2/framework/ldtest"
+	o "github.com/launchdarkly/sdk-test-harness/v2/framework/opt"
+	"github.com/launchdarkly/sdk-test-harness/v2/servicedef"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// CommonInstanceIDTests groups together event-related test methods that are shared between server-side and client-side.
+type CommonInstanceIDTests struct {
+	commonTestsBase
+}
+
+func NewCommonInstanceIDTests(t *ldtest.T, testName string, baseSDKConfigurers ...SDKConfigurer) CommonInstanceIDTests {
+	return CommonInstanceIDTests{newCommonTestsBase(t, testName, baseSDKConfigurers...)}
+}
+
+func (c CommonInstanceIDTests) Run(t *ldtest.T) {
+	t.RequireCapability(servicedef.CapabilityInstanceID)
+
+	verifyRequestHeader := func(t *ldtest.T, endpoint *harness.MockEndpoint) {
+		request := endpoint.RequireConnection(t, time.Second)
+		assert.NotEmpty(t, request.Headers.Get("X-LaunchDarkly-Instance-Id"))
+	}
+
+	t.Run("stream requests", func(t *ldtest.T) {
+		dataSource := NewSDKDataSource(t, nil, DataSourceOptionStreaming())
+		configurers := c.baseSDKConfigurationPlus(dataSource)
+		if c.isClientSide {
+			// client-side SDKs in streaming mode may *also* need a polling data source
+			configurers = append(configurers,
+				NewSDKDataSource(t, nil, DataSourceOptionPolling()))
+		}
+		_ = NewSDKClient(t, configurers...)
+		verifyRequestHeader(t, dataSource.Endpoint())
+	})
+
+	t.Run("poll requests", func(t *ldtest.T) {
+		t.Capabilities().HasAny(servicedef.CapabilityServerSidePolling, servicedef.CapabilityClientSide)
+
+		dataSource := NewSDKDataSource(t, nil, DataSourceOptionPolling())
+		_ = NewSDKClient(t, c.baseSDKConfigurationPlus(dataSource)...)
+		verifyRequestHeader(t, dataSource.Endpoint())
+	})
+
+	t.Run("event posts", func(t *ldtest.T) {
+		dataSource := NewSDKDataSource(t, nil)
+		events := NewSDKEventSink(t)
+		client := NewSDKClient(t, c.baseSDKConfigurationPlus(
+			dataSource,
+			events)...)
+
+		c.sendArbitraryEvent(t, client)
+		client.FlushEvents(t)
+
+		verifyRequestHeader(t, events.Endpoint())
+	})
+}
+
+func (c CommonInstanceIDTests) RunPHP(t *ldtest.T) {
+	t.RequireCapability(servicedef.CapabilityInstanceID)
+
+	verifyRequestHeader := func(t *ldtest.T, endpoint *harness.MockEndpoint) {
+		request := endpoint.RequireConnection(t, time.Second)
+		assert.NotEmpty(t, request.Headers.Get("X-LaunchDarkly-Instance-Id"))
+	}
+
+	t.Run("poll requests", func(t *ldtest.T) {
+		dataSource := NewSDKDataSource(t, nil)
+		client := NewSDKClient(t, c.baseSDKConfigurationPlus(dataSource)...)
+		client.EvaluateFlag(t, servicedef.EvaluateFlagParams{
+			FlagKey:      "flag-key",
+			Context:      o.Some(ldcontext.New("key")),
+			ValueType:    servicedef.ValueTypeBool,
+			DefaultValue: ldvalue.Bool(false),
+			Detail:       false,
+		})
+
+		verifyRequestHeader(t, dataSource.Endpoint())
+	})
+
+	t.Run("event posts", func(t *ldtest.T) {
+		dataSource := NewSDKDataSource(t, nil)
+		events := NewSDKEventSink(t)
+		client := NewSDKClient(t, c.baseSDKConfigurationPlus(
+			dataSource,
+			events)...)
+
+		c.sendArbitraryEvent(t, client)
+		client.FlushEvents(t)
+
+		verifyRequestHeader(t, events.Endpoint())
+	})
+}

sdktests/testsuite_entry_point.go

@@ -87,6 +87,9 @@ func doAllServerSideTests(t *ldtest.T) {
 	t.Run("big segments", doServerSideBigSegmentsTests)
 	t.Run("service endpoints", doServerSideServiceEndpointsTests)
 	t.Run("tags", doServerSideTagsTests)
+	t.Run("instance id", func(t *ldtest.T) {
+		NewCommonInstanceIDTests(t, "doServerSideInstanceIdTests").Run(t)
+	})
 	t.Run("secure mode hash", doServerSideSecureModeHashTests)
 	t.Run("context type", doSDKContextTypeTests)
 	t.Run("migrations", doServerSideMigrationTests)
@@ -101,6 +104,9 @@ func doAllClientSideTests(t *ldtest.T) {
 	t.Run("streaming", doClientSideStreamTests)
 	t.Run("polling", doClientSidePollTests)
 	t.Run("tags", doClientSideTagsTests)
+	t.Run("instance id", func(t *ldtest.T) {
+		NewCommonInstanceIDTests(t, "doClientSideInstanceIdTests").Run(t)
+	})
 	t.Run("context type", doSDKContextTypeTests)
 	t.Run("autoEnvAttributes", doClientSideAutoEnvAttributesTests)
 	t.Run("client independence", doClientSideClientIndependenceTests)
@@ -115,6 +121,9 @@ func doAllPHPTests(t *ldtest.T) {
 	t.Run("secure mode hash", doServerSideSecureModeHashTests)
 	t.Run("migrations", doServerSideMigrationTests)
 	t.Run("big segments", doServerSideBigSegmentsTests)
+	t.Run("instance id", func(t *ldtest.T) {
+		NewCommonInstanceIDTests(t, "doPHPInstanceIdTests").RunPHP(t)
+	})
 }
 
 func allImportantServerSideCapabilities() framework.Capabilities {

servicedef/service_params.go

@@ -36,6 +36,7 @@ const (
 	CapabilityETagCaching                 = "etag-caching"
 	CapabilityInlineContext               = "inline-context"
 	CapabilityInlineContextAll            = "inline-context-all"
+	CapabilityInstanceID                  = "instance-id"
 	CapabilityAnonymousRedaction          = "anonymous-redaction"
 	CapabilityPollingGzip                 = "polling-gzip"
 	CapabilityEvaluationHooks             = "evaluation-hooks"