setup code sharing between go apps

.circleci/config.yml

@@ -60,6 +60,17 @@ jobs:
           name: Run tests
           command: make test-ci
 
+  shared:
+    docker:
+      - image: circleci/golang:1.12
+    working_directory: ~/offen/shared
+    steps:
+      - checkout:
+          path: ~/offen
+      - run:
+          name: Run tests
+          command: make test
+
   vault:
     docker:
       - image: circleci/node:10-browsers
@@ -150,3 +161,4 @@ workflows:
       - script
       - auditorium
       - packages
+      - shared

docker-compose.yml

@@ -3,11 +3,11 @@ version: '3'
 services:
   kms:
     image: golang:1.12
-    working_dir: /kms
+    working_dir: /code/kms
     volumes:
-      - ./kms:/kms
-      - ./local.offen.dev.pem:/kms/local.offen.dev.pem
-      - ./local.offen.dev-key.pem:/kms/local.offen.dev-key.pem
+      - .:/code
+      - ./local.offen.dev.pem:/code/kms/local.offen.dev.pem
+      - ./local.offen.dev-key.pem:/code/kms/local.offen.dev-key.pem
       - $GOPATH/pkg/mod:/go/pkg/mod
     environment:
       - GOPATH=/go
@@ -18,11 +18,11 @@ services:
 
   server:
     image: golang:1.12
-    working_dir: /server
+    working_dir: /code/server
     volumes:
-      - ./server:/server
-      - ./local.offen.dev.pem:/server/local.offen.dev.pem
-      - ./local.offen.dev-key.pem:/server/local.offen.dev-key.pem
+      - .:/code
+      - ./local.offen.dev.pem:/code/server/local.offen.dev.pem
+      - ./local.offen.dev-key.pem:/code/server/local.offen.dev-key.pem
       - $GOPATH/pkg/mod:/go/pkg/mod
     environment:
       - GOPATH=/go

shared/Makefile

@@ -0,0 +1,2 @@
+test:
+	@go test -race -cover ./...

shared/README.md

@@ -0,0 +1,15 @@
+# shared
+
+`shared` contains Go packages shared across applications. Consumers need to symlink the folder into their app directory.
+
+---
+
+## Development
+
+### Commands
+
+#### Run the tests
+
+```
+make test
+```

shared/http/errors.go

@@ -0,0 +1,22 @@
+package http
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type errorResponse struct {
+	Error  string `json:"error"`
+	Status int    `json:"status"`
+}
+
+func jsonError(err error, status int) []byte {
+	r := errorResponse{err.Error(), status}
+	b, _ := json.Marshal(r)
+	return b
+}
+
+func RespondWithJSONError(w http.ResponseWriter, err error, status int) {
+	w.WriteHeader(status)
+	w.Write(jsonError(err, status))
+}

shared/http/errors_test.go

@@ -0,0 +1,19 @@
+package http
+
+import (
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestRespondWithJSONError(t *testing.T) {
+	w := httptest.NewRecorder()
+	RespondWithJSONError(w, errors.New("does not work"), http.StatusInternalServerError)
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("Unexpected status code %d", w.Code)
+	}
+	if w.Body.String() != `{"error":"does not work","status":500}` {
+		t.Errorf("Unexpected response body %s", w.Body.String())
+	}
+}

shared/http/middleware.go

@@ -0,0 +1,29 @@
+package http
+
+import "net/http"
+
+func CorsMiddleware(next http.Handler, origin string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Credentials", "true")
+		w.Header().Set("Access-Control-Allow-Methods", "POST,GET")
+		w.Header().Set("Access-Control-Allow-Origin", origin)
+		next.ServeHTTP(w, r)
+	})
+}
+
+func ContentTypeMiddleware(next http.Handler, contentType string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("Content-Type", contentType)
+		next.ServeHTTP(w, r)
+	})
+}
+
+func DoNotTrackMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if dnt := r.Header.Get("DNT"); dnt == "1" {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}

shared/http/middleware_test.go

@@ -0,0 +1,82 @@
+package http
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestCorsMiddleware(t *testing.T) {
+	t.Run("default", func(t *testing.T) {
+		wrapped := CorsMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write([]byte("OK"))
+		}), "https://www.example.net")
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		wrapped.ServeHTTP(w, r)
+		if h := w.Header().Get("Access-Control-Allow-Origin"); h != "https://www.example.net" {
+			t.Errorf("Unexpected header value %v", h)
+		}
+	})
+}
+
+func TestContentTypeMiddleware(t *testing.T) {
+	t.Run("default", func(t *testing.T) {
+		wrapped := ContentTypeMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write([]byte("OK"))
+		}), "application/json")
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		wrapped.ServeHTTP(w, r)
+		if h := w.Header().Get("Content-Type"); h != "application/json" {
+			t.Errorf("Unexpected header value %v", h)
+		}
+	})
+}
+
+func TestDoNotTrackMiddleware(t *testing.T) {
+	wrapped := DoNotTrackMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("hey there"))
+	}))
+	t.Run("with header", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		r.Header.Set("DNT", "1")
+		wrapped.ServeHTTP(w, r)
+
+		if w.Code != http.StatusNoContent {
+			t.Errorf("Unexpected status code %d", w.Code)
+		}
+
+		if w.Body.String() != "" {
+			t.Errorf("Unexpected response body %s", w.Body.String())
+		}
+	})
+	t.Run("without header", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		wrapped.ServeHTTP(w, r)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Unexpected status code %d", w.Code)
+		}
+
+		if w.Body.String() != "hey there" {
+			t.Errorf("Unexpected response body %s", w.Body.String())
+		}
+	})
+	t.Run("with header allowing", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		r.Header.Set("DNT", "0")
+		wrapped.ServeHTTP(w, r)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Unexpected status code %d", w.Code)
+		}
+
+		if w.Body.String() != "hey there" {
+			t.Errorf("Unexpected response body %s", w.Body.String())
+		}
+	})
+}