Add env endpoint (#21)

Author: maruina

README.md

@@ -1,11 +1,12 @@
 # go-infrabin
 
-[![Build Status](https://travis-ci.org/maruina/go-infrabin.svg?branch=master)](https://travis-ci.org/maruina/go-infrabin)
 [![Go Report Card](https://goreportcard.com/badge/github.com/maruina/go-infrabin)](https://goreportcard.com/report/github.com/maruina/go-infrabin)
 [![Coverage Status](https://coveralls.io/repos/github/maruina/go-infrabin/badge.svg?branch=master)](https://coveralls.io/github/maruina/go-infrabin?branch=master)
 
 [infrabin](https://github.com/maruina/infrabin) written in go.
 
+**Warning: `go-infrabin` exposes sensitive endpoints and should NEVER be used on the public Internet.**
+
 ## Usage
 
 `go-infrabin` exposes two ports:
@@ -52,6 +53,17 @@ To override the default values:
     }
     ```
 
+* `GET /env/<env_var>`
+  * _returns_: a JSON response with the requested `<env_var>` or `404` if the environment variable does not exist
+
+    ```json
+    {
+        "env": {
+            "<env_var>": "<env_var_value>"
+        }
+    }
+    ```
+
 ## Admin Endpoints
 
 * `GET /liveness`

cmd/go-infrabin/main.go

@@ -97,6 +97,36 @@ func HeadersHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// EnvHandler handles the env endpoint
+func EnvHandler(w http.ResponseWriter, r *http.Request) {
+	var resp helpers.Response
+	vars := mux.Vars(r)
+	w.Header().Set("Content-Type", "application/json")
+	value := helpers.GetEnv(vars["env_var"], "")
+
+	if value == "" {
+		data := helpers.MarshalResponseToString(resp)
+		w.WriteHeader(http.StatusNotFound)
+		_, err := io.WriteString(w, data)
+		if err != nil {
+			log.Fatal("error writing to ResponseWriter", err)
+		}
+	} else {
+
+		resp.Env = map[string]string{
+			vars["env_var"]: value,
+		}
+		data := helpers.MarshalResponseToString(resp)
+
+		w.WriteHeader(http.StatusOK)
+		_, err := io.WriteString(w, data)
+		if err != nil {
+			log.Fatal("error writing to ResponseWriter", err)
+		}
+
+	}
+}
+
 func main() {
 	r := mux.NewRouter()
 	a := mux.NewRouter()
@@ -105,6 +135,7 @@ func main() {
 	r.HandleFunc("/", RootHandler)
 	r.HandleFunc("/delay/{seconds}", DelayHandler)
 	r.HandleFunc("/headers", HeadersHandler)
+	r.HandleFunc("/env/{env_var}", EnvHandler)
 
 	a.HandleFunc("/liveness", LivenessHandler)
 

cmd/go-infrabin/main_test.go

@@ -191,3 +191,51 @@ func TestHeadersHandler(t *testing.T) {
 			rr.Body.String(), data)
 	}
 }
+
+func TestEnvHandler(t *testing.T) {
+	if err := os.Setenv("TEST_ENV", "foo"); err != nil {
+		t.Errorf("cannot set environment variable")
+	}
+	req, err := http.NewRequest("GET", "/env", nil)
+	req = mux.SetURLVars(req, map[string]string{"env_var": "TEST_ENV"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(EnvHandler)
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusOK {
+		t.Errorf("handler returned wrong status code: got %v want %v",
+			status, http.StatusOK)
+	}
+
+	var expected helpers.Response
+	expected.Env = map[string]string{
+		"TEST_ENV": "foo",
+	}
+	data := helpers.MarshalResponseToString(expected)
+
+	if rr.Body.String() != data {
+		t.Errorf("handler returned unexpected body: got %v want %v",
+			rr.Body.String(), data)
+	}
+}
+
+func TestEnvHandlerNotFound(t *testing.T) {
+	req, err := http.NewRequest("GET", "/env", nil)
+	req = mux.SetURLVars(req, map[string]string{"env_var": "NOT_FOUND"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(EnvHandler)
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusNotFound {
+		t.Errorf("handler returned wrong status code: got %v want %v",
+			status, http.StatusNotFound)
+	}
+}

internal/helpers/struct.go

@@ -8,12 +8,13 @@ import (
 
 // Response creates the go-infrabin main response
 type Response struct {
-	Hostname     string        `json:"hostname,omitempty"`
-	KubeResponse *KubeResponse `json:"kubernetes,omitempty"`
-	Liveness     string        `json:"liveness,omitempty"`
-	Delay        string        `json:"delay,omitempty"`
-	Error        string        `json:"error,omitempty"`
-	Headers      *http.Header  `json:"headers,omitempty"`
+	Hostname     string            `json:"hostname,omitempty"`
+	KubeResponse *KubeResponse     `json:"kubernetes,omitempty"`
+	Liveness     string            `json:"liveness,omitempty"`
+	Delay        string            `json:"delay,omitempty"`
+	Error        string            `json:"error,omitempty"`
+	Headers      *http.Header      `json:"headers,omitempty"`
+	Env          map[string]string `json:"env,omitempty"`
 }
 
 // KubeResponse creates the response if running on Kubernetes