feat(image-build): add the ability to build images (#1672)

api/http/proxy/build.go

@@ -0,0 +1,56 @@
+package proxy
+
+import (
+	"bytes"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
+	"github.com/portainer/portainer/archive"
+)
+
+type postDockerfileRequest struct {
+	Content string
+}
+
+// buildOperation inspects the "Content-Type" header to determine if it needs to alter the request.
+// If the value of the header is empty, it means that a Dockerfile is posted via upload, the function
+// will extract the file content from the request body, tar it, and rewrite the body.
+// If the value of the header contains "application/json", it means that the content of a Dockerfile is posted
+// in the request payload as JSON, the function will create a new file called Dockerfile inside a tar archive and
+// rewrite the body of the request.
+// In any other case, it will leave the request unaltered.
+func buildOperation(request *http.Request) error {
+	contentTypeHeader := request.Header.Get("Content-Type")
+	if contentTypeHeader != "" && !strings.Contains(contentTypeHeader, "application/json") {
+		return nil
+	}
+
+	var dockerfileContent []byte
+
+	if contentTypeHeader == "" {
+		body, err := ioutil.ReadAll(request.Body)
+		if err != nil {
+			return err
+		}
+		dockerfileContent = body
+	} else {
+		var req postDockerfileRequest
+		if err := json.NewDecoder(request.Body).Decode(&req); err != nil {
+			return err
+		}
+		dockerfileContent = []byte(req.Content)
+	}
+
+	buffer, err := archive.TarFileInBuffer(dockerfileContent, "Dockerfile")
+	if err != nil {
+		return err
+	}
+
+	request.Body = ioutil.NopCloser(bytes.NewReader(buffer))
+	request.ContentLength = int64(len(buffer))
+	request.Header.Set("Content-Type", "application/x-tar")
+
+	return nil
+}