feat: support Cloudflare Workers AI (#1068)

Co-authored-by: Kent Dong <ch3cho@qq.com>

plugins/wasm-go/extensions/ai-proxy/provider/cloudflare.go

@@ -0,0 +1,108 @@
+package provider
+
+import (
+	"errors"
+	"fmt"
+	"github.com/alibaba/higress/plugins/wasm-go/extensions/ai-proxy/util"
+	"github.com/alibaba/higress/plugins/wasm-go/pkg/wrapper"
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
+	"strings"
+)
+
+const (
+	cloudflareDomain = "api.cloudflare.com"
+	// https://developers.cloudflare.com/workers-ai/configuration/open-ai-compatibility/
+	cloudflareChatCompletionPath = "/client/v4/accounts/{account_id}/ai/v1/chat/completions"
+)
+
+type cloudflareProviderInitializer struct {
+}
+
+func (c *cloudflareProviderInitializer) ValidateConfig(config ProviderConfig) error {
+	return nil
+}
+
+func (c *cloudflareProviderInitializer) CreateProvider(config ProviderConfig) (Provider, error) {
+	return &cloudflareProvider{
+		config:       config,
+		contextCache: createContextCache(&config),
+	}, nil
+}
+
+type cloudflareProvider struct {
+	config       ProviderConfig
+	contextCache *contextCache
+}
+
+func (c *cloudflareProvider) GetProviderType() string {
+	return providerTypeCloudflare
+}
+
+func (c *cloudflareProvider) OnRequestHeaders(ctx wrapper.HttpContext, apiName ApiName, log wrapper.Log) (types.Action, error) {
+	if apiName != ApiNameChatCompletion {
+		return types.ActionContinue, errUnsupportedApiName
+	}
+	_ = util.OverwriteRequestPath(strings.Replace(cloudflareChatCompletionPath, "{account_id}", c.config.cloudflareAccountId, 1))
+	_ = util.OverwriteRequestHost(cloudflareDomain)
+	_ = proxywasm.ReplaceHttpRequestHeader("Authorization", "Bearer "+c.config.GetRandomToken())
+
+	if c.config.context == nil && c.config.protocol == protocolOriginal {
+		ctx.DontReadRequestBody()
+	}
+	_ = proxywasm.RemoveHttpRequestHeader("Accept-Encoding")
+	_ = proxywasm.RemoveHttpRequestHeader("Content-Length")
+
+	return types.ActionContinue, nil
+}
+
+func (c *cloudflareProvider) OnRequestBody(ctx wrapper.HttpContext, apiName ApiName, body []byte, log wrapper.Log) (types.Action, error) {
+	if apiName != ApiNameChatCompletion {
+		return types.ActionContinue, errUnsupportedApiName
+	}
+
+	request := &chatCompletionRequest{}
+	if err := decodeChatCompletionRequest(body, request); err != nil {
+		return types.ActionContinue, err
+	}
+	model := request.Model
+	if model == "" {
+		return types.ActionContinue, errors.New("missing model in chat completion request")
+	}
+	ctx.SetContext(ctxKeyOriginalRequestModel, model)
+	mappedModel := getMappedModel(model, c.config.modelMapping, log)
+	if mappedModel == "" {
+		return types.ActionContinue, errors.New("model becomes empty after applying the configured mapping")
+	}
+	request.Model = mappedModel
+	ctx.SetContext(ctxKeyFinalRequestModel, request.Model)
+
+	streaming := request.Stream
+	if streaming {
+		_ = proxywasm.ReplaceHttpRequestHeader("Accept", "text/event-stream")
+	}
+
+	if c.contextCache == nil {
+		if err := replaceJsonRequestBody(request, log); err != nil {
+			_ = util.SendResponse(500, util.MimeTypeTextPlain, fmt.Sprintf("failed to replace request body: %v", err))
+		}
+		return types.ActionContinue, nil
+	}
+	err := c.contextCache.GetContent(func(content string, err error) {
+		defer func() {
+			_ = proxywasm.ResumeHttpRequest()
+		}()
+		if err != nil {
+			log.Errorf("failed to load context file: %v", err)
+			_ = util.SendResponse(500, util.MimeTypeTextPlain, fmt.Sprintf("failed to load context file: %v", err))
+		}
+		insertContextMessage(request, content)
+		if err := replaceJsonRequestBody(request, log); err != nil {
+			_ = util.SendResponse(500, util.MimeTypeTextPlain, fmt.Sprintf("failed to replace request body: %v", err))
+		}
+	}, log)
+	if err == nil {
+		return types.ActionPause, nil
+	}
+	return types.ActionContinue, err
+}