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proxy.go
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proxy.go
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package dispatch
import (
"context"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/aws/aws-lambda-go/events"
)
// HTTPProxy is a handler function suitable for use in http.HandleFunc.
// For example:
//
// http.HandleFunc("/", api.HTTPProxy)
// log.Fatal(http.ListenAndServe(":8000", nil))
//
// The provided handler takes care of access control headers, CORS requests,
// JSON marshalling, and error handling.
func (api *API) HTTPProxy(w http.ResponseWriter, r *http.Request) {
wroteHeader := 200
wroteStatus := http.StatusText(200)
startTime := time.Now()
defer func() {
fmt.Printf("%v %s%s - %d %s\n", time.Since(startTime), r.Method, r.URL.Path, wroteHeader, wroteStatus)
}()
writeError := func(w http.ResponseWriter, error string, code int) {
wroteHeader = code
wroteStatus = http.StatusText(code)
http.Error(w, error, code)
}
w.Header().Set("Access-Control-Allow-Origin", "*")
// w.Header().Set("Access-Control-Allow-Methods", "PUT, POST, GET, DELETE, OPTIONS")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
if r.Method == "OPTIONS" {
validMethods := api.GetMethodsForPath(r.URL.Path)
w.Header().Set("Access-Control-Allow-Methods", strings.Join(validMethods, ", "))
w.WriteHeader(200)
return
}
data, err := ioutil.ReadAll(r.Body)
if err != nil {
writeError(w, err.Error(), http.StatusInternalServerError)
return
}
// TODO: Limit each call with timeout
ctx := context.Background()
output, err := api.Call(ctx, r.Method, r.URL.Path, data)
if err != nil {
switch err {
case ErrNotFound:
writeError(w, err.Error(), http.StatusNotFound)
case ErrBadRequest:
writeError(w, err.Error(), http.StatusBadRequest)
default:
writeError(w, err.Error(), http.StatusInternalServerError)
}
return
}
outBytes, err := json.Marshal(output)
if err != nil {
writeError(w, err.Error(), http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "application/json")
w.Write(outBytes)
}
// LambdaProxy returns a handler function suitable for use with github.com/aws/aws-lambda-go/lambda.
// For example:
//
// import "github.com/aws/aws-lambda-go/lambda"
// func main() {
// lambda.Start(api.LambdaProxy("*"))
// }
//
// The provided handler takes care of access control headers, CORS requests,
// JSON marshalling, and error handling.
func (api *API) LambdaProxy(corsAllowedOrigin string) func(*events.APIGatewayProxyRequest) (*events.APIGatewayProxyResponse, error) {
return func(apr *events.APIGatewayProxyRequest) (*events.APIGatewayProxyResponse, error) {
response := &events.APIGatewayProxyResponse{
Headers: make(map[string]string),
}
startTime := time.Now()
defer func() {
fmt.Printf("%v %s%s - %d\n", time.Since(startTime), apr.HTTPMethod, apr.Path, response.StatusCode)
}()
writeError := func(err string, code int) {
response.Body = err
response.StatusCode = code
}
response.Headers["Access-Control-Allow-Origin"] = corsAllowedOrigin
response.Headers["Access-Control-Allow-Headers"] = "Authorization, Content-Type"
if apr.HTTPMethod == "OPTIONS" {
validMethods := api.GetMethodsForPath(apr.Path)
response.Headers["Access-Control-Allow-Methods"] = strings.Join(validMethods, ", ")
response.StatusCode = http.StatusOK
return response, nil
}
data := []byte(apr.Body)
// TODO: Limit each call with timeout
ctx := context.Background()
ctx = SetContextLambdaRequest(ctx, apr)
ctx = SetContextLambdaResponse(ctx, response)
output, err := api.Call(ctx, apr.HTTPMethod, apr.Path, data)
if err != nil {
if apiErr, ok := err.(*APIError); ok {
writeError(apiErr.Error(), apiErr.StatusCode)
return response, nil
}
switch err {
case ErrNotFound:
writeError(err.Error(), http.StatusNotFound)
case ErrBadRequest:
writeError(err.Error(), http.StatusBadRequest)
default:
writeError(err.Error(), http.StatusInternalServerError)
}
return response, nil
}
outBytes, err := json.Marshal(output)
if err != nil {
writeError(err.Error(), http.StatusInternalServerError)
return response, nil
}
response.Headers["Content-Type"] = "application/json"
response.Body = string(outBytes)
response.StatusCode = http.StatusOK
return response, nil
}
}
// APIGatewayUserID returns the subject from the proxy request's authorizer.
func APIGatewayUserID(ctx events.APIGatewayProxyRequestContext) string {
if ctx.Authorizer == nil {
return ""
}
claims := ctx.Authorizer["claims"]
if claims == nil {
return ""
}
claimsMap, ok := claims.(map[string]interface{})
if !ok {
return ""
}
userID := claimsMap["sub"]
if userID == nil {
return ""
}
id, ok := userID.(string)
if !ok {
return ""
}
return id
}