Add github action to run lint on PRs (#6)

* add github action to run lint on PRs

.github/workflows/pr.yml

@@ -0,0 +1,21 @@
+name: PR
+on: [pull_request]
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Go 1.13
+        uses: actions/setup-go@v1
+        with:
+          go-version: 1.13
+        id: go
+
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v1
+
+      - name: Setup Lint
+        run: curl -LO https://github.com/golangci/golangci-lint/releases/download/v1.19.1/golangci-lint-1.19.1-linux-amd64.tar.gz && tar -xf golangci-lint-1.19.1-linux-amd64.tar.gz
+
+      - name: Lint
+        run: golangci-lint-1.19.1-linux-amd64/golangci-lint run

system_certificate_local.go

@@ -128,10 +128,18 @@ func createCertificateForm(name, password string, cert, key []byte) (form *bytes
 	w := multipart.NewWriter(&b)
 	defer w.Close()
 
-	w.WriteField("mkey", name)
-	w.WriteField("vdom", "global")
-	w.WriteField("type", "CertKey")
-	w.WriteField("passwd", password)
+	fields := map[string]string{
+		"mkey":   name,
+		"vdom":   "global",
+		"type":   "CertKey",
+		"passwd": password,
+	}
+	for field, value := range fields {
+		err := w.WriteField(field, value)
+		if err != nil {
+			return &b, contentType, err
+		}
+	}
 
 	certPart, err := w.CreateFormFile("cert", "tls.crt")
 	if err != nil {