feat: init dynamic modules work

.github/workflows/pr_style_check.yaml

@@ -87,6 +87,7 @@ jobs:
             refactor
             mcp
             aigw
+            dynamic_module
           subjectPattern: ^(?![A-Z]).+$
           subjectPatternError: |
             The subject "{subject}" found in the pull request title "{title}"

Makefile

@@ -270,6 +270,11 @@ build.%: ## Build a binary for the given command under the internal/cmd director
 build: ## Build all binaries under cmd/ directory.
 	@$(foreach COMMAND_NAME,$(COMMANDS),$(MAKE) build.$(COMMAND_NAME);)
 
+# This builds the dynamic module filter for Envoy. This is the shared library that can be loaded by Envoy to run the AI Gateway filter.
+.PHONE: build-dm
+build-dm: ## Build the dynamic module for Envoy.
+	CGO_ENABLED=1 go build -tags "envoy_1.36" -buildmode=c-shared -o $(OUTPUT_DIR)/libaigateway.so ./cmd/dynamic_module
+
 # This builds the docker images for the controller, extproc and testupstream for the e2e tests.
 .PHONY: build-e2e
 build-e2e: ## Build the docker images for the controller, extproc and testupstream for the e2e tests.

cmd/dynamic_module/main.go

@@ -0,0 +1,114 @@
+// Copyright Envoy AI Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	otelprom "go.opentelemetry.io/otel/exporters/prometheus"
+
+	"github.com/envoyproxy/ai-gateway/internal/backendauth"
+	"github.com/envoyproxy/ai-gateway/internal/dynamicmodule"
+	"github.com/envoyproxy/ai-gateway/internal/dynamicmodule/sdk"
+	"github.com/envoyproxy/ai-gateway/internal/filterapi"
+	"github.com/envoyproxy/ai-gateway/internal/internalapi"
+	"github.com/envoyproxy/ai-gateway/internal/metrics"
+)
+
+func main() {} // This must be present to make a shared library.
+
+// Set the envoy.NewHTTPFilter function to create a new http filter.
+func init() {
+	g := &globalState{}
+	if err := g.initializeEnv(); err != nil {
+		panic("failed to create env config: " + err.Error())
+	}
+
+	// TODO: use a writer implemented with the Logger ABI of Envoy.
+	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelDebug, // Adjust log level from environment variable if needed.
+	}))
+	if err := filterapi.StartConfigWatcher(context.Background(),
+		os.Getenv("AI_GATEWAY_dynamicmodule_FILTER_CONFIG_PATH"), g, logger, time.Second*5); err != nil {
+		panic("failed to start filter config watcher: " + err.Error())
+	}
+	sdk.NewHTTPFilterConfig = g.newHTTPFilterConfig
+}
+
+// globalState implements [filterapi.ConfigReceiver] to load filter configuration.
+type globalState struct {
+	fc  *filterapi.RuntimeConfig
+	env *dynamicmodule.Env
+}
+
+// newHTTPFilterConfig creates a new http filter based on the config.
+//
+// `config` is the configuration string that is specified in the Envoy configuration.
+func (g *globalState) newHTTPFilterConfig(name string, _ []byte) sdk.HTTPFilterConfig {
+	switch name {
+	case "ai_gateway.router":
+		return dynamicmodule.NewRouterFilterConfig(g.env, &g.fc)
+	case "ai_gateway.upstream":
+		return dynamicmodule.NewUpstreamFilterConfig(g.env)
+	default:
+		panic("unknown filter: " + name)
+	}
+}
+
+// LoadConfig implements [filterapi.ConfigReceiver.LoadConfig].
+func (g *globalState) LoadConfig(ctx context.Context, config *filterapi.Config) error {
+	newConfig, err := filterapi.NewRuntimeConfig(ctx, config, backendauth.NewHandler)
+	if err != nil {
+		return fmt.Errorf("cannot create runtime filter config: %w", err)
+	}
+	g.fc = newConfig // This is racy but we don't care.
+	return nil
+}
+
+func (g *globalState) initializeEnv() error {
+	ctx := context.Background()
+	promRegistry := prometheus.NewRegistry()
+	promReader, err := otelprom.New(otelprom.WithRegisterer(promRegistry))
+	if err != nil {
+		return fmt.Errorf("failed to create prometheus reader: %w", err)
+	}
+
+	meter, _, err := metrics.NewMeterFromEnv(ctx, os.Stdout, promReader)
+	if err != nil {
+		return fmt.Errorf("failed to create metrics: %w", err)
+	}
+
+	endpointPrefixes, err := internalapi.ParseEndpointPrefixes(os.Getenv(
+		"AI_GATEWAY_dynamicmodule_FILTER_ENDPOINT_PREFIXES",
+	))
+	if err != nil {
+		return fmt.Errorf("failed to parse endpoint prefixes: %w", err)
+	}
+
+	metricsRequestHeaderAttributes, err := internalapi.ParseRequestHeaderAttributeMapping(os.Getenv(
+		"AI_GATEWAY_dynamicmodule_FILTER_METRICS_REQUEST_HEADER_ATTRIBUTES",
+	))
+	if err != nil {
+		return fmt.Errorf("failed to parse metrics header mapping: %w", err)
+	}
+
+	g.env = &dynamicmodule.Env{
+		RootPrefix:                    os.Getenv("AI_GATEWAY_dynamicmodule_ROOT_PREFIX"),
+		EndpointPrefixes:              endpointPrefixes,
+		ChatCompletionMetricsFactory:  metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationChat),
+		MessagesMetricsFactory:        metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationMessages),
+		CompletionMetricsFactory:      metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationCompletion),
+		EmbeddingsMetricsFactory:      metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationEmbedding),
+		ImageGenerationMetricsFactory: metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationImageGeneration),
+		RerankMetricsFactory:          metrics.NewMetricsFactory(meter, metricsRequestHeaderAttributes, metrics.GenAIOperationRerank),
+	}
+	return nil
+}

internal/dynamicmodule/dynamic_module.go

@@ -0,0 +1,43 @@
+// Copyright Envoy AI Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package dynamicmodule
+
+import (
+	"github.com/envoyproxy/ai-gateway/internal/internalapi"
+	"github.com/envoyproxy/ai-gateway/internal/metrics"
+)
+
+// endpoint represents the type of the endpoint that the request is targeting.
+type endpoint int
+
+const (
+	// chatCompletionsEndpoint represents the /v1/chat/completions endpoint.
+	chatCompletionsEndpoint endpoint = iota
+	// completionsEndpoint represents the /v1/completions endpoint.
+	completionsEndpoint
+	// embeddingsEndpoint represents the /v1/embeddings endpoint.
+	embeddingsEndpoint
+	// imagesGenerationsEndpoint represents the /v1/images/generations endpoint.
+	imagesGenerationsEndpoint
+	// rerankEndpoint represents the /v2/rerank endpoint of cohere.
+	rerankEndpoint
+	// messagesEndpoint represents the /v1/messages endpoint of anthropic.
+	messagesEndpoint
+	// modelsEndpoint represents the /v1/models endpoint.
+	modelsEndpoint
+)
+
+// Env holds the environment configuration for the dynamic module that is process-wide.
+type Env struct {
+	RootPrefix       string
+	EndpointPrefixes internalapi.EndpointPrefixes
+	ChatCompletionMetricsFactory,
+	MessagesMetricsFactory,
+	CompletionMetricsFactory,
+	EmbeddingsMetricsFactory,
+	ImageGenerationMetricsFactory,
+	RerankMetricsFactory metrics.Factory
+}

internal/dynamicmodule/router_filter.go

@@ -0,0 +1,194 @@
+// Copyright Envoy AI Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package dynamicmodule
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"path"
+	"strings"
+	"unsafe"
+
+	openaisdk "github.com/openai/openai-go/v2"
+
+	"github.com/envoyproxy/ai-gateway/internal/apischema/anthropic"
+	cohereschema "github.com/envoyproxy/ai-gateway/internal/apischema/cohere"
+	"github.com/envoyproxy/ai-gateway/internal/apischema/openai"
+	"github.com/envoyproxy/ai-gateway/internal/dynamicmodule/sdk"
+	"github.com/envoyproxy/ai-gateway/internal/filterapi"
+	"github.com/envoyproxy/ai-gateway/internal/internalapi"
+)
+
+const routerFilterPointerDynamicMetadataKey = "router_filter_pointer"
+
+type (
+	// routerFilterConfig implements [sdk.HTTPFilterConfig].
+	//
+	// This is mostly for debugging purposes, it does not do anything except
+	// setting a response header with the version of the dynamic module.
+	routerFilterConfig struct {
+		fcr              **filterapi.RuntimeConfig
+		prefixToEndpoint map[string]endpoint
+	}
+	// routerFilter implements [sdk.HTTPFilter].
+	routerFilter struct {
+		routerFilterConfig     *routerFilterConfig
+		runtimeFilterConfig    *filterapi.RuntimeConfig
+		endpoint               endpoint
+		originalHeaders        map[string]string
+		originalRequestBody    any
+		originalRequestBodyRaw []byte
+		span                   any
+		attemptCount           int
+	}
+)
+
+// NewRouterFilterConfig creates a new instance of an implementation of [sdk.HTTPFilterConfig] for the router filter.
+func NewRouterFilterConfig(env *Env, fcr **filterapi.RuntimeConfig) sdk.HTTPFilterConfig {
+	prefixToEndpoint := map[string]endpoint{
+		path.Join(env.RootPrefix, env.EndpointPrefixes.OpenAI, "/v1/chat/completions"):   chatCompletionsEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.OpenAI, "/v1/completions"):        completionsEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.OpenAI, "/v1/embeddings"):         embeddingsEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.OpenAI, "/v1/images/generations"): imagesGenerationsEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.Cohere, "/v2/rerank"):             rerankEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.OpenAI, "/v1/models"):             modelsEndpoint,
+		path.Join(env.RootPrefix, env.EndpointPrefixes.Anthropic, "/v1/messages"):        messagesEndpoint,
+	}
+	return &routerFilterConfig{
+		fcr:              fcr,
+		prefixToEndpoint: prefixToEndpoint,
+	}
+}
+
+// NewFilter implements [sdk.HTTPFilterConfig].
+func (f *routerFilterConfig) NewFilter() sdk.HTTPFilter {
+	return &routerFilter{routerFilterConfig: f, runtimeFilterConfig: *f.fcr}
+}
+
+// RequestHeaders implements [sdk.HTTPFilter].
+func (f *routerFilter) RequestHeaders(e sdk.EnvoyHTTPFilter, _ bool) sdk.RequestHeadersStatus {
+	p, _ := e.GetRequestHeader(":path") // The :path pseudo header is always present.
+	// Strip query parameters for processor lookup.
+	if queryIndex := strings.Index(p, "?"); queryIndex != -1 {
+		p = p[:queryIndex]
+	}
+	ep, ok := f.routerFilterConfig.prefixToEndpoint[p]
+	if !ok {
+		e.SendLocalReply(404, nil, []byte(fmt.Sprintf("unsupported path: %s", p)))
+		return sdk.RequestHeadersStatusStopIteration
+	}
+	f.endpoint = ep
+	if f.endpoint == modelsEndpoint {
+		return f.handleModelsEndpoint(e)
+	}
+	return sdk.RequestHeadersStatusContinue
+}
+
+// RequestBody implements [sdk.HTTPFilter].
+func (f *routerFilter) RequestBody(e sdk.EnvoyHTTPFilter, endOfStream bool) sdk.RequestBodyStatus {
+	if !endOfStream {
+		return sdk.RequestBodyStatusStopIterationAndBuffer
+	}
+	b, ok := e.GetRequestBody()
+	if !ok {
+		e.SendLocalReply(400, nil, []byte("failed to read request body"))
+		return sdk.RequestBodyStatusStopIterationAndBuffer
+	}
+	raw, err := io.ReadAll(b)
+	if err != nil {
+		e.SendLocalReply(400, nil, []byte("failed to read request body: "+err.Error()))
+		return sdk.RequestBodyStatusStopIterationAndBuffer
+	}
+	f.originalRequestBodyRaw = raw
+	var parsed any
+	var modelName string
+	switch f.endpoint {
+	case chatCompletionsEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *openai.ChatCompletionRequest) string { return req.Model })
+	case completionsEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *openai.CompletionRequest) string { return req.Model })
+	case embeddingsEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *openai.EmbeddingRequest) string { return req.Model })
+	case imagesGenerationsEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *openaisdk.ImageGenerateParams) string { return req.Model })
+	case rerankEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *cohereschema.RerankV2Request) string { return req.Model })
+	case messagesEndpoint:
+		parsed, modelName, err = parseBodyWithModel(raw, func(req *anthropic.MessagesRequest) string { return req.GetModel() })
+	default:
+		e.SendLocalReply(500, nil, []byte("BUG: unsupported endpoint at body parsing: "+fmt.Sprintf("%d", f.endpoint)))
+	}
+	if err != nil {
+		e.SendLocalReply(400, nil, []byte("failed to parse request body: "+err.Error()))
+		return sdk.RequestBodyStatusStopIterationAndBuffer
+	}
+	f.originalRequestBody = parsed
+	if !e.SetRequestHeader(internalapi.ModelNameHeaderKeyDefault, []byte(modelName)) {
+		e.SendLocalReply(500, nil, []byte("failed to set model name header"))
+		return sdk.RequestBodyStatusStopIterationAndBuffer
+	}
+	// Store the pointer to the filter in dynamic metadata for later retrieval in the upstream filter.
+	e.SetDynamicMetadataString(internalapi.AIGatewayFilterMetadataNamespace, routerFilterPointerDynamicMetadataKey,
+		fmt.Sprintf("%d", uintptr(unsafe.Pointer(f))))
+
+	f.originalHeaders = multiValueHeadersToSingleValue(e.GetRequestHeaders())
+	return sdk.RequestBodyStatusContinue
+}
+
+// ResponseHeaders implements [sdk.HTTPFilter].
+func (f *routerFilter) ResponseHeaders(sdk.EnvoyHTTPFilter, bool) sdk.ResponseHeadersStatus {
+	return sdk.ResponseHeadersStatusContinue
+}
+
+// ResponseBody implements [sdk.HTTPFilter].
+func (f *routerFilter) ResponseBody(sdk.EnvoyHTTPFilter, bool) sdk.ResponseBodyStatus {
+	return sdk.ResponseBodyStatusContinue
+}
+
+// handleModelsEndpoint handles the /v1/models endpoint by returning the list of declared models in the filter configuration.
+//
+// This is called on request headers phase.
+func (f *routerFilter) handleModelsEndpoint(e sdk.EnvoyHTTPFilter) sdk.RequestHeadersStatus {
+	config := f.runtimeFilterConfig
+	models := openai.ModelList{
+		Object: "list",
+		Data:   make([]openai.Model, 0, len(config.DeclaredModels)),
+	}
+	for _, m := range config.DeclaredModels {
+		models.Data = append(models.Data, openai.Model{
+			ID:      m.Name,
+			Object:  "model",
+			OwnedBy: m.OwnedBy,
+			Created: openai.JSONUNIXTime(m.CreatedAt),
+		})
+	}
+
+	body, _ := json.Marshal(models)
+	e.SendLocalReply(200, [][2]string{
+		{"content-type", "application/json"},
+	}, body)
+	return sdk.RequestHeadersStatusStopIteration
+}
+
+func parseBodyWithModel[T any](body []byte, modelExtractFn func(req *T) string) (interface{}, string, error) {
+	var req T
+	if err := json.Unmarshal(body, &req); err != nil {
+		return nil, "", fmt.Errorf("failed to unmarshal body: %w", err)
+	}
+	return req, modelExtractFn(&req), nil
+}
+
+// multiValueHeadersToSingleValue converts a map of headers with multiple values to a map of headers with single values by taking the first value for each header.
+//
+// TODO: this is purely for feature parity with the old filter where we ignore the case of multiple header values.
+func multiValueHeadersToSingleValue(headers map[string][]string) map[string]string {
+	singleValueHeaders := make(map[string]string, len(headers))
+	for k, v := range headers {
+		singleValueHeaders[k] = v[0]
+	}
+	return singleValueHeaders
+}