Add support for ALB for the Chi adapter

chi/adapterALB.go

@@ -0,0 +1,59 @@
+package chiadapter
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/aws/aws-lambda-go/events"
+	"github.com/awslabs/aws-lambda-go-api-proxy/core"
+	"github.com/go-chi/chi/v5"
+)
+
+// ChiLambdaALB makes it easy to send ALB proxy events to a chi.Mux.
+// The library transforms the proxy event into an HTTP request and then
+// creates a proxy response object from the http.ResponseWriter
+type ChiLambdaALB struct {
+	core.RequestAccessorALB
+
+	Chi *chi.Mux
+}
+
+// NewALB creates a new instance of the ChiLambdaALB object.
+// Receives an initialized *chi.Mux object - normally created with chi.New().
+// It returns the initialized instance of the ChiLambdaALB object.
+func NewALB(chi *chi.Mux) *ChiLambdaALB {
+	return &ChiLambdaALB{Chi: chi}
+}
+
+// Proxy receives an ALB proxy event, transforms it into an http.Request
+// object, and sends it to the chi.Mux for routing.
+// It returns a proxy response object generated from the http.ResponseWriter.
+func (c *ChiLambdaALB) Proxy(req events.ALBTargetGroupRequest) (events.ALBTargetGroupResponse, error) {
+	chiRequest, err := c.ProxyEventToHTTPRequest(req)
+	return c.proxyInternal(chiRequest, err)
+}
+
+// ProxyWithContext receives an ALB proxy event, transforms it into an http.Request
+// object, and sends it to the chi.Mux for routing.
+// It returns a proxy response object generated from the http.ResponseWriter.
+func (c *ChiLambdaALB) ProxyWithContext(ctx context.Context, req events.ALBTargetGroupRequest) (events.ALBTargetGroupResponse, error) {
+	chiRequest, err := c.EventToRequestWithContext(ctx, req)
+	return c.proxyInternal(chiRequest, err)
+}
+
+func (c *ChiLambdaALB) proxyInternal(req *http.Request, err error) (events.ALBTargetGroupResponse, error) {
+
+	if err != nil {
+		return core.GatewayTimeoutALB(), core.NewLoggedError("Could not convert proxy event to request: %v", err)
+	}
+
+	respWriter := core.NewProxyResponseWriterALB()
+	c.Chi.ServeHTTP(http.ResponseWriter(respWriter), req)
+
+	proxyResponse, err := respWriter.GetProxyResponse()
+	if err != nil {
+		return core.GatewayTimeoutALB(), core.NewLoggedError("Error while generating proxy response: %v", err)
+	}
+
+	return proxyResponse, nil
+}

chi/chilambda_test.go

@@ -41,3 +41,30 @@ var _ = Describe("ChiLambda tests", func() {
 		})
 	})
 })
+
+var _ = Describe("ChiLambdaALB tests", func() {
+	Context("Simple ping request", func() {
+		It("Proxies the event correctly", func() {
+			log.Println("Starting test")
+
+			r := chi.NewRouter()
+			r.Get("/ping", func(w http.ResponseWriter, r *http.Request) {
+				w.Write([]byte("pong"))
+			})
+
+			adapter := chiadapter.NewALB(r)
+
+			req := events.ALBTargetGroupRequest{
+				HTTPMethod: "GET",
+				Path:       "/ping",
+				RequestContext: events.ALBTargetGroupRequestContext{
+					ELB: events.ELBContext{TargetGroupArn: " ad"},
+				}}
+
+			resp, err := adapter.Proxy(req)
+
+			Expect(err).To(BeNil())
+			Expect(resp.StatusCode).To(Equal(200))
+		})
+	})
+})

core/requestALB.go

@@ -115,7 +115,15 @@ func (r *RequestAccessorALB) EventToRequest(req events.ALBTargetGroupRequest) (*
 	if !strings.HasPrefix(path, "/") {
 		path = "/" + path
 	}
-	serverAddress := "https://" + req.Headers["host"]
+
+	host := req.Headers["host"]
+	if _, ok := req.Headers["host"]; !ok {
+		if req.MultiValueHeaders["host"] != nil && len(req.MultiValueHeaders["host"]) > 0 {
+			host = req.MultiValueHeaders["host"][0]
+		}
+	}
+
+	serverAddress := "https://" + host
 	//  if customAddress, ok := os.LookupEnv(CustomHostVariable); ok {
 	//  	serverAddress = customAddress
 	//  }