chore(lint): fix revive, unconvert, and testifylint in image generation and tracing

- Ignore unused parameters in tests and translator (revive)\n- Remove unnecessary string conversions now that model types are strings (unconvert)\n- Use require.Empty for empty string check (testifylint)\n- Remove unused test variable in span tests (unused)\n- Keep extractUsageFromBufferEvent with lint ignore for future parity

Signed-off-by: Hrushikesh Patil <[email protected]>

Author: nutanix-Hrushikesh

.gitignore

@@ -49,3 +49,5 @@ inference-extension-conformance-test-report.yaml
 
 .goose
 tests/e2e-inference-extension/logs/
+
+/aigw

cmd/aigw/README.md

@@ -61,6 +61,21 @@ Here are values we use for Ollama:
      ```
      This calls the kiwi MCP server through aigw's MCP Gateway at `/mcp`.
 
+   - Image generation:
+     - Using service:
+       ```bash
+       docker compose run --rm image-generation
+       ```
+     - Using curl (save to file):
+       ```bash
+       curl -s \
+         -X POST http://localhost:1975/v1/images/generations \
+         -H "Authorization: Bearer unused" \
+         -H "Content-Type: application/json" \
+         -d '{"model":"gpt-image-1","prompt":"A watercolor painting of a red fox in a birch forest","size":"512x512"}' \
+         | jq -r '.data[0].b64_json' | base64 -d > image.png
+       ```
+
 4. **Create embeddings**:
 
    The `create-embeddings` service uses `curl` to send an embeddings request
@@ -163,6 +178,8 @@ This configures the OTLP endpoint to otel-tui on port 4318.
    COMPOSE_PROFILES="<profile>" docker compose -f docker-compose-otel.yaml run --build --rm chat-completion
    COMPOSE_PROFILES="<profile>" docker compose -f docker-compose-otel.yaml run --build --rm create-embeddings
    COMPOSE_PROFILES="<profile>" docker compose -f docker-compose-otel.yaml run --build --rm mcp
+   # Image generation
+   COMPOSE_PROFILES="<profile>" docker compose -f docker-compose-otel.yaml run --build --rm image-generation
    ```
 
 3. **Check telemetry output**:

cmd/aigw/docker-compose.yaml

@@ -135,3 +135,23 @@ services:
       - flyTo=LAX
       - --tool-arg
       - departureDate=15/12/2025
+
+  # image-generation is a simple curl-based test client for sending image
+  # generation requests to aigw.
+  image-generation:
+    image: golang:1.25
+    container_name: image-generation
+    profiles: ["test"]
+    env_file:
+      - ../../.env.ollama
+    command:
+      - sh
+      - -c
+      - |
+        curl -s -w %{http_code} \
+          -X POST http://aigw:1975/v1/images/generations \
+          -H "Authorization: Bearer unused" \
+          -H "Content-Type: application/json" \
+          -d "{\"model\":\"$$CHAT_MODEL\",\"prompt\":\"A watercolor painting of a red fox in a birch forest\",\"size\":\"256x256\"}"
+    extra_hosts:  # localhost:host-gateway trick doesn't work with aigw
+      - "host.docker.internal:host-gateway"

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.12.0
 	github.com/a8m/envsubst v1.4.3
 	github.com/alecthomas/kong v1.12.1
+	github.com/andybalholm/brotli v1.2.0
 	github.com/anthropics/anthropic-sdk-go v1.12.0
 	github.com/aws/aws-sdk-go-v2 v1.39.1
 	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.1
@@ -83,7 +84,6 @@ require (
 	github.com/AzureAD/microsoft-authentication-library-for-go v1.5.0 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/NYTimes/gziphandler v1.1.1 // indirect
-	github.com/andybalholm/brotli v1.2.0 // indirect
 	github.com/antlr4-go/antlr/v4 v4.13.1 // indirect
 	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
 	github.com/avast/retry-go v3.0.0+incompatible // indirect

go.sum

@@ -447,6 +447,8 @@ github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
 github.com/xiang90/probing v0.0.0-20221125231312-a49e3df8f510 h1:S2dVYn90KE98chqDkyE9Z4N61UnQd+KOfgp5Iu53llk=
 github.com/xiang90/probing v0.0.0-20221125231312-a49e3df8f510/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
+github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
+github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
 github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
 github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

internal/extproc/imagegeneration_processor.go

@@ -18,6 +18,7 @@ import (
 	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
 	extprocv3http "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/http/ext_proc/v3"
 	extprocv3 "github.com/envoyproxy/go-control-plane/envoy/service/ext_proc/v3"
+	openaisdk "github.com/openai/openai-go/v2"
 	"google.golang.org/protobuf/types/known/structpb"
 
 	"github.com/envoyproxy/ai-gateway/internal/extproc/backendauth"
@@ -27,7 +28,6 @@ import (
 	"github.com/envoyproxy/ai-gateway/internal/internalapi"
 	"github.com/envoyproxy/ai-gateway/internal/metrics"
 	tracing "github.com/envoyproxy/ai-gateway/internal/tracing/api"
-	openaisdk "github.com/openai/openai-go/v2"
 )
 
 // ImageGenerationProcessorFactory returns a factory method to instantiate the image generation processor.
@@ -215,11 +215,11 @@ func (i *imageGenerationProcessorUpstreamFilter) ProcessRequestHeaders(ctx conte
 	// Start tracking metrics for this request.
 	i.metrics.StartRequest(i.requestHeaders)
 	// Set the original model from the request body before any overrides
-	i.metrics.SetOriginalModel(internalapi.OriginalModel(i.originalRequestBody.Model))
+	i.metrics.SetOriginalModel(i.originalRequestBody.Model)
 	// Set the request model for metrics from the original model or override if applied.
-	reqModel := cmp.Or(i.requestHeaders[i.config.modelNameHeaderKey], string(i.originalRequestBody.Model))
-	i.metrics.SetRequestModel(internalapi.RequestModel(reqModel))
-	i.metrics.SetResponseModel(internalapi.ResponseModel(reqModel))
+	reqModel := cmp.Or(i.requestHeaders[i.config.modelNameHeaderKey], i.originalRequestBody.Model)
+	i.metrics.SetRequestModel(reqModel)
+	i.metrics.SetResponseModel(reqModel)
 
 	// We force the body mutation in the following cases:
 	// * The request is a retry request because the body mutation might have happened the previous iteration.
@@ -471,9 +471,9 @@ func (i *imageGenerationProcessorUpstreamFilter) SetBackend(ctx context.Context,
 	i.headerMutator = headermutator.NewHeaderMutator(b.HeaderMutation, rp.requestHeaders)
 	// Sync header with backend model so header-derived labels/CEL use the actual model.
 	if i.modelNameOverride != "" {
-		i.requestHeaders[i.config.modelNameHeaderKey] = string(i.modelNameOverride)
+		i.requestHeaders[i.config.modelNameHeaderKey] = i.modelNameOverride
 		// Update metrics with the overridden model
-		i.metrics.SetRequestModel(internalapi.RequestModel(i.modelNameOverride))
+		i.metrics.SetRequestModel(i.modelNameOverride)
 	}
 	i.originalRequestBody = rp.originalRequestBody
 	i.originalRequestBodyRaw = rp.originalRequestBodyRaw
@@ -498,5 +498,5 @@ func parseOpenAIImageGenerationBody(body *extprocv3.HttpBody) (modelName string,
 	if err := json.Unmarshal(body.Body, &openAIReq); err != nil {
 		return "", nil, fmt.Errorf("failed to unmarshal body: %w", err)
 	}
-	return string(openAIReq.Model), &openAIReq, nil
+	return openAIReq.Model, &openAIReq, nil
 }

internal/extproc/imagegeneration_processor_test.go

@@ -15,13 +15,13 @@ import (
 
 	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
 	extprocv3 "github.com/envoyproxy/go-control-plane/envoy/service/ext_proc/v3"
+	openaisdk "github.com/openai/openai-go/v2"
 	"github.com/stretchr/testify/require"
 
 	"github.com/envoyproxy/ai-gateway/internal/extproc/translator"
 	"github.com/envoyproxy/ai-gateway/internal/filterapi"
 	"github.com/envoyproxy/ai-gateway/internal/llmcostcel"
 	tracing "github.com/envoyproxy/ai-gateway/internal/tracing/api"
-	openaisdk "github.com/openai/openai-go/v2"
 )
 
 func TestImageGeneration_Schema(t *testing.T) {
@@ -95,7 +95,7 @@ func (m *mockImageGenerationSpan) EndSpanOnError(status int, body []byte) {
 	m.errBody = string(body)
 }
 
-func (m *mockImageGenerationSpan) RecordResponse(resp *openaisdk.ImagesResponse) {
+func (m *mockImageGenerationSpan) RecordResponse(_ *openaisdk.ImagesResponse) {
 	// Mock implementation
 }
 
@@ -390,7 +390,7 @@ type mockImageGenerationTranslator struct {
 	retImageMetadata            translator.ImageGenerationMetadata
 }
 
-func (m *mockImageGenerationTranslator) RequestBody(original []byte, req *openaisdk.ImageGenerateParams, forceBodyMutation bool) (*extprocv3.HeaderMutation, *extprocv3.BodyMutation, error) {
+func (m *mockImageGenerationTranslator) RequestBody(_ []byte, req *openaisdk.ImageGenerateParams, forceBodyMutation bool) (*extprocv3.HeaderMutation, *extprocv3.BodyMutation, error) {
 	if m.expRequestBody != nil {
 		require.Equal(m.t, m.expRequestBody, req)
 	}
@@ -410,6 +410,7 @@ func (m *mockImageGenerationTranslator) ResponseHeaders(headers map[string]strin
 }
 
 func (m *mockImageGenerationTranslator) ResponseBody(headers map[string]string, body io.Reader, endOfStream bool) (*extprocv3.HeaderMutation, *extprocv3.BodyMutation, translator.LLMTokenUsage, translator.ImageGenerationMetadata, error) {
+	_ = headers
 	if m.expResponseBody != nil {
 		bodyBytes, _ := io.ReadAll(body)
 		require.Equal(m.t, m.expResponseBody.Body, bodyBytes)
@@ -419,13 +420,15 @@ func (m *mockImageGenerationTranslator) ResponseBody(headers map[string]string,
 }
 
 func (m *mockImageGenerationTranslator) ResponseError(headers map[string]string, body io.Reader) (*extprocv3.HeaderMutation, *extprocv3.BodyMutation, error) {
+	_ = headers
+	_ = body
 	return m.retHeaderMutation, m.retBodyMutation, m.retErr
 }
 
 // imageGenerationBodyFromModel returns a minimal valid image generation request for tests.
 func imageGenerationBodyFromModel(t *testing.T, model string) []byte {
 	t.Helper()
-	b, err := json.Marshal(&openaisdk.ImageGenerateParams{Model: openaisdk.ImageModel(model), Prompt: "a cat"})
+	b, err := json.Marshal(&openaisdk.ImageGenerateParams{Model: model, Prompt: "a cat"})
 	require.NoError(t, err)
 	return b
 }

internal/extproc/mocks_test.go

@@ -410,47 +410,57 @@ func (m *mockImageGenerationMetrics) StartRequest(map[string]string) {}
 func (m *mockImageGenerationMetrics) SetOriginalModel(originalModel string) {
 	m.model = originalModel
 }
+
 func (m *mockImageGenerationMetrics) SetRequestModel(requestModel string) {
 	m.model = requestModel
 }
+
 func (m *mockImageGenerationMetrics) SetResponseModel(responseModel string) {
 	m.model = responseModel
 }
-func (m *mockImageGenerationMetrics) SetModel(requestModel, responseModel string) {
+
+func (m *mockImageGenerationMetrics) SetModel(_ string, responseModel string) {
 	m.model = responseModel
 }
 func (m *mockImageGenerationMetrics) SetBackend(b *filterapi.Backend) { m.backend = b.Name }
 func (m *mockImageGenerationMetrics) RecordTokenUsage(_ context.Context, input, output uint32, _ map[string]string) {
 	m.tokenUsageCount += int(input + output)
 }
+
 func (m *mockImageGenerationMetrics) RecordRequestCompletion(_ context.Context, success bool, _ map[string]string) {
 	if success {
 		m.requestSuccessCount++
 	} else {
 		m.requestErrorCount++
 	}
 }
+
 func (m *mockImageGenerationMetrics) RecordImageGeneration(_ context.Context, _ int, _ string, _ string, _ map[string]string) {
 }
 
 func (m *mockImageGenerationMetrics) RequireRequestFailure(t *testing.T) {
 	require.Equal(t, 0, m.requestSuccessCount)
 	require.Equal(t, 1, m.requestErrorCount)
 }
+
 func (m *mockImageGenerationMetrics) RequireRequestNotCompleted(t *testing.T) {
 	require.Equal(t, 0, m.requestSuccessCount)
 	require.Equal(t, 0, m.requestErrorCount)
 }
+
 func (m *mockImageGenerationMetrics) RequireRequestSuccess(t *testing.T) {
 	require.Equal(t, 1, m.requestSuccessCount)
 	require.Equal(t, 0, m.requestErrorCount)
 }
+
 func (m *mockImageGenerationMetrics) RequireSelectedModel(t *testing.T, model string) {
 	require.Equal(t, model, m.model)
 }
+
 func (m *mockImageGenerationMetrics) RequireSelectedBackend(t *testing.T, backend string) {
 	require.Equal(t, backend, m.backend)
 }
+
 func (m *mockImageGenerationMetrics) RequireTokensRecorded(t *testing.T, count int) {
 	require.Equal(t, count, m.tokenUsageCount)
 }

internal/extproc/translator/imagegeneration_openai_openai.go

@@ -14,11 +14,11 @@ import (
 
 	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
 	extprocv3 "github.com/envoyproxy/go-control-plane/envoy/service/ext_proc/v3"
+	openaisdk "github.com/openai/openai-go/v2"
 	"github.com/tidwall/sjson"
 
 	"github.com/envoyproxy/ai-gateway/internal/internalapi"
 	tracing "github.com/envoyproxy/ai-gateway/internal/tracing/api"
-	openaisdk "github.com/openai/openai-go/v2"
 )
 
 // NewImageGenerationOpenAIToOpenAITranslator implements [Factory] for OpenAI to OpenAI image generation translation.
@@ -36,7 +36,7 @@ type openAIToOpenAIImageGenerationTranslator struct {
 }
 
 // RequestBody implements [ImageGenerationTranslator.RequestBody].
-func (o *openAIToOpenAIImageGenerationTranslator) RequestBody(original []byte, req *openaisdk.ImageGenerateParams, forceBodyMutation bool) (
+func (o *openAIToOpenAIImageGenerationTranslator) RequestBody(original []byte, _ *openaisdk.ImageGenerateParams, forceBodyMutation bool) (
 	headerMutation *extprocv3.HeaderMutation, bodyMutation *extprocv3.BodyMutation, err error,
 ) {
 	var newBody []byte
@@ -172,7 +172,9 @@ func (o *openAIToOpenAIImageGenerationTranslator) ResponseBody(_ map[string]stri
 // extractUsageFromBufferEvent extracts token usage from buffered streaming events.
 // This is currently not applicable for image generation as it doesn't use streaming.
 // TODO: Implement if streaming support is added for image generation in the future.
-func (o *openAIToOpenAIImageGenerationTranslator) extractUsageFromBufferEvent(span tracing.ImageGenerationSpan) LLMTokenUsage {
-	// Image generation doesn't use streaming, so no token usage to extract
+// NOTE: image generation currently does not use streaming; keep for future parity with other translators.
+//
+//lint:ignore U1000 kept for parity and future use
+func (o *openAIToOpenAIImageGenerationTranslator) extractUsageFromBufferEvent(_ tracing.ImageGenerationSpan) LLMTokenUsage {
 	return LLMTokenUsage{}
 }

internal/extproc/translator/imagegeneration_openai_openai_test.go

@@ -10,9 +10,8 @@ import (
 	"encoding/json"
 	"testing"
 
-	"github.com/stretchr/testify/require"
-
 	openaisdk "github.com/openai/openai-go/v2"
+	"github.com/stretchr/testify/require"
 )
 
 func TestOpenAIToOpenAIImageTranslator_RequestBody_ModelOverrideAndPath(t *testing.T) {
@@ -32,7 +31,7 @@ func TestOpenAIToOpenAIImageTranslator_RequestBody_ModelOverrideAndPath(t *testi
 	mutated := bm.GetBody()
 	var got openaisdk.ImageGenerateParams
 	require.NoError(t, json.Unmarshal(mutated, &got))
-	require.Equal(t, "gpt-image-1", string(got.Model))
+	require.Equal(t, "gpt-image-1", got.Model)
 }
 
 func TestOpenAIToOpenAIImageTranslator_RequestBody_ForceMutation(t *testing.T) {
@@ -81,6 +80,6 @@ func TestOpenAIToOpenAIImageTranslator_ResponseBody_OK(t *testing.T) {
 	require.Equal(t, uint32(0), usage.InputTokens)
 	require.Equal(t, uint32(0), usage.TotalTokens)
 	require.Equal(t, 0, metadata.ImageCount)
-	require.Equal(t, "", metadata.Model)
+	require.Empty(t, metadata.Model)
 	require.Equal(t, string(openaisdk.ImagesResponseSize1024x1024), metadata.Size)
 }