Implement PreSigned Url

We generated a Presigned Url for PUT and GET

PUT Presigned url will be used to make a put request to upload an image to our S3 bucket

GET presinged url will be used to load an image

Both links expires after 5 mins

FYI: I did some code refactoring in for our multiplexer. Route matching with the julienschmidt multiplexer was so bad!
gin-gonic/gin#1301

aws/filestore.go

@@ -0,0 +1,78 @@
+package aws
+
+import (
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/udacity/udagram-restapi-golang/config"
+)
+
+var (
+	c = config.NewConfig()
+)
+
+type S3client struct {
+	client *s3.S3
+}
+
+// Creates a S3 client
+func createS3Client() *s3.S3 {
+
+	/*
+		Initialize a session that the SDK will use to load
+		credentials from the shared credentials file ~/.aws/credentials
+		and region from the shared configuration file ~/.aws/config.
+	*/
+	sess := session.Must(session.NewSessionWithOptions(session.Options{
+		SharedConfigState: session.SharedConfigEnable,
+		Profile:           c.Aws_profile,
+	}))
+
+	svc := s3.New(sess, aws.NewConfig().WithRegion(c.Aws_region))
+	return svc
+}
+
+// NewDynamoDbRepo creates a new DynamoDb Repository
+func NewS3client() *S3client {
+	s3c := createS3Client()
+
+	return &S3client{s3c}
+}
+
+/* GetGetSignedUrl generates an aws signed url to retreive an item
+ * @Params
+ *    key: string - the filename to be put into the s3 bucket
+ * @Returns:
+ *    a url as a string and error
+ */
+func (s *S3client) GetGetSignedUrl(key string) (string, error) {
+
+	req, _ := s.client.GetObjectRequest(&s3.GetObjectInput{
+		Bucket: aws.String(c.Aws_media_bucket),
+		Key:    aws.String(key),
+	})
+
+	urlStr, err := req.Presign(5 * time.Minute) //we want the expire time of the url to be about 5 minutes
+
+	return urlStr, err
+
+}
+
+/* GetPutSignedUrl generates an aws signed url to put an item
+ * @Params
+ *    key: string - the filename to be retreived from s3 bucket
+ * @Returns:
+ *    a url as a string and error
+ */
+func (s *S3client) GetPutSignedUrl(key string) (string, error) {
+	req, _ := s.client.PutObjectRequest(&s3.PutObjectInput{
+		Bucket: aws.String(c.Aws_media_bucket),
+		Key:    aws.String(key),
+	})
+
+	urlStr, err := req.Presign(5 * time.Minute) //we want the expire time of the url to be about 5 minutes
+
+	return urlStr, err
+}

controllers/v0/feed/feed.router.go

@@ -5,10 +5,10 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/julienschmidt/httprouter"
+	"github.com/gorilla/mux"
 )
 
-func IndexHandler(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+func IndexHandler(w http.ResponseWriter, r *http.Request) {
 	fds, err := AllFeedItems()
 	if err != nil {
 		log.Printf("Problem getting all feeds: %s", err.Error())
@@ -22,7 +22,7 @@ func IndexHandler(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 	w.Write(body)
 }
 
-func CreateFeedItemHandler(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+func CreateFeedItemHandler(w http.ResponseWriter, r *http.Request) {
 	i, err := PostFeedItem(r)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusNotAcceptable)
@@ -34,10 +34,10 @@ func CreateFeedItemHandler(w http.ResponseWriter, r *http.Request, _ httprouter.
 	w.Write(body)
 }
 
-func GetFeedItemHandler(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
-	id := ps.ByName("id")
-	//validation to make sure there is an id present
-	if id == "" {
+func GetFeedItemHandler(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	id, ok := vars["id"]
+	if !ok {
 		http.Error(w, http.StatusText(400), http.StatusBadRequest)
 		return
 	}
@@ -52,3 +52,26 @@ func GetFeedItemHandler(w http.ResponseWriter, r *http.Request, ps httprouter.Pa
 	w.Header().Set("Content-Type", "application/json")
 	w.Write(body) //we return the record to the client in a sensible payload
 }
+
+func GetGetSignedUrlHandler(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	fn, ok := vars["fileName"]
+	if !ok {
+		http.Error(w, http.StatusText(400), http.StatusBadRequest)
+		return
+	}
+
+	url, err := GetGetSignedUrl(fn)
+	if err != nil {
+		log.Printf("Problem getting signed url for %s: %s", fn, err.Error())
+
+		http.Error(w, http.StatusText(500), http.StatusInternalServerError)
+		return
+	}
+
+	body, _ := json.Marshal(map[string]interface{}{
+		"url": url,
+	})
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Write(body) //we return the record to the client in a sensible payload
+}

controllers/v0/feed/feedItem.go

@@ -21,9 +21,13 @@ type FeedItem struct {
 
 type CreateFeedItemRequest struct {
 	Caption string `json:"caption"`
-	Url     string `json:"url"`
+	Url     string `json:"url"` //eg: imageName.jpeg
 }
 
+var (
+	s3s = aws.NewS3client()
+)
+
 func AllFeedItems() ([]FeedItem, error) {
 	rows, err := aws.DB.Query("SELECT id, caption, url, created_at, updated_at FROM feeditem;")
 	if err != nil {
@@ -43,6 +47,15 @@ func AllFeedItems() ([]FeedItem, error) {
 	if err = rows.Err(); err != nil {
 		return nil, err
 	}
+
+	for i, f := range fis {
+		u, err := s3s.GetGetSignedUrl(f.Url)
+		if err != nil {
+			log.Printf("Error getting getSignedUrl for key %s: %s", f.Url, err.Error())
+		}
+		fis[i].Url = u
+	}
+
 	return fis, nil
 }
 
@@ -57,7 +70,7 @@ func PostFeedItem(req *http.Request) (FeedItem, error) {
 	}
 
 	item.Caption = ni.Caption
-	item.Url = "https://s3-us-west-1.amazonaws.com/udacity-content/images/icon-eror.svg" //mock value for now
+	item.Url = ni.Url
 	item.CreatedAt = time.Now().Format(time.RFC3339)
 	item.UpdatedAt = time.Now().Format(time.RFC3339)
 
@@ -86,3 +99,9 @@ func GetFeedItem(id string) (FeedItem, error) {
 
 	return fi, nil
 }
+
+func GetGetSignedUrl(key string) (string, error) {
+	//c := aws.NewS3client()
+
+	return s3s.GetPutSignedUrl(key)
+}

go.mod

@@ -3,6 +3,8 @@ module github.com/udacity/udagram-restapi-golang
 go 1.16
 
 require (
+	github.com/aws/aws-sdk-go v1.38.40 // indirect
+	github.com/gorilla/mux v1.8.0 // indirect
 	github.com/julienschmidt/httprouter v1.3.0
 	github.com/lib/pq v1.10.1
 )

go.sum

@@ -1,4 +1,27 @@
+github.com/aws/aws-sdk-go v1.38.40 h1:VVqBFV24tGgXR11tFXPjmR+0ItbnUepbuQjdmhgu3U0=
+github.com/aws/aws-sdk-go v1.38.40/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/jmespath/go-jmespath v0.4.0 h1:BEgLn5cpjn8UN1mAw4NjwDrS35OdebyEtFe+9YPoQUg=
+github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHWvzYPziyZiYoo=
+github.com/jmespath/go-jmespath/internal/testify v1.5.1/go.mod h1:L3OGu8Wl2/fWfCI6z80xFu9LTZmf1ZRjMHUOPmWr69U=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/lib/pq v1.10.1 h1:6VXZrLU0jHBYyAqrSPa+MgPfnSvTPuMgK+k0o5kVFWo=
 github.com/lib/pq v1.10.1/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20201110031124-69a78807bb2b/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

@@ -5,7 +5,7 @@ import (
 	"net/http"
 	"os"
 
-	"github.com/julienschmidt/httprouter"
+	"github.com/gorilla/mux"
 	fh "github.com/udacity/udagram-restapi-golang/controllers/v0/feed"
 )
 
@@ -15,15 +15,35 @@ func main() {
 		port = "8080"
 	}
 
-	mux := httprouter.New()
+	r := mux.NewRouter()
 
-	mux.GET("/", index)
-	mux.GET("/api/v0/feed", fh.IndexHandler)
-	mux.POST("/api/v0/feed", fh.CreateFeedItemHandler)
-	mux.GET("/api/v0/feed/:id", fh.GetFeedItemHandler)
-	http.ListenAndServe(":"+port, mux)
+	/*
+		Create a "Subrouter" dedicated to /api which will use the PathPrefix
+		more on nesting routes with gorrila mux here https://stackoverflow.com/questions/25107763/nested-gorilla-mux-router-does-not-work
+		https://binx.io/blog/2018/11/27/go-gorilla/
+	*/
+	apiRouter := mux.NewRouter().PathPrefix("/api").Subrouter().StrictSlash(true)
+
+	// This step is where we connect our "root" router and our "Subrouter" together.
+	r.PathPrefix("/api").Handler(apiRouter)
+
+	// Define "root" routes using r
+	r.Methods("GET").Path("/").HandlerFunc(index)
+
+	// Define "Subrouter" routes using apiRouter, prefix is /api
+	apiRouter.Methods("GET").Path("/").HandlerFunc(api)
+	apiRouter.Methods("GET").Path("/v0/feed").HandlerFunc(fh.IndexHandler)
+	apiRouter.Methods("POST").Path("/v0/feed").HandlerFunc(fh.CreateFeedItemHandler)
+	apiRouter.Methods("GET").Path("/v0/feed/{id}").HandlerFunc(fh.GetFeedItemHandler)
+	apiRouter.Methods("GET").Path("/v0/feed/signed-url/{fileName}").HandlerFunc(fh.GetGetSignedUrlHandler)
+
+	http.ListenAndServe(":"+port, r)
 }
 
-func index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+func index(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprintln(w, "/api/v0/")
 }
+
+func api(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintln(w, "v0")
+}