Bump actions/setup-go from 4 to 5

Bumps [actions/setup-go](https://github.com/actions/setup-go) from 4 to 5.
- [Release notes](https://github.com/actions/setup-go/releases)
- [Commits](https://github.com/actions/setup-go/compare/v4...v5)

---
updated-dependencies:
- dependency-name: actions/setup-go
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docker-image.yml

@@ -7,6 +7,20 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3.1.0
+      - uses: actions/checkout@v4.1.1
       - name: Build the Docker image
-        run: docker build . --file Dockerfile --tag yosoy-local:$(date +%s)
+        run: docker build . --file Dockerfile --tag yosoy-local:latest
+      - name: Run simple integration test
+        run: |
+          docker run -p 3333:80 yosoy-local:latest > yosoy.log &
+          sleep 5
+          RESULT=$(curl -s -X DELETE -H 'x-api-key: abc123' 'http://0.0.0.0:3333/sample/path?with=params')
+          echo "$RESULT"
+          if [[ $RESULT =~ '"method":"DELETE"' ]]
+          then
+            echo 'Test successful'
+            exit 0
+          else
+            echo 'Test failure'
+            exit 1
+          fi

.github/workflows/docker-publish.yml

@@ -15,16 +15,16 @@ jobs:
       contents: read
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3.1.0
+        uses: actions/checkout@v4.1.1
 
       - name: Log in to Docker Hub
-        uses: docker/login-action@v2
+        uses: docker/login-action@v3
         with:
           username: ${{ secrets.DOCKER_HUB_USERNAME }}
           password: ${{ secrets.DOCKER_HUB_TOKEN }}
 
       - name: Log in to the Container registry
-        uses: docker/login-action@v2
+        uses: docker/login-action@v3
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
@@ -32,7 +32,7 @@ jobs:
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v4
+        uses: docker/metadata-action@v5
         with:
           images: |
             lukasz/yosoy
@@ -44,7 +44,7 @@ jobs:
             type=semver,pattern={{major}}
 
       - name: Build and push Docker images
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v5
         with:
           context: .
           push: true

.github/workflows/go.yml

@@ -6,12 +6,12 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3.1.0
+      - uses: actions/checkout@v4.1.1
 
       - name: Set up Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v5
         with:
-          go-version: 1.16
+          go-version: 1.19
 
       - name: Build
         run: go build -v ./...

.gitignore

@@ -1,2 +1,3 @@
 debug.test
+cover.out
 yosoy

Dockerfile

@@ -1,12 +1,16 @@
-FROM golang:1.17.3-alpine3.13 as builder
+FROM golang:1.21-alpine as builder
 
 LABEL maintainer="Łukasz Budnik lukasz.budnik@gmail.com"
 
+# install prerequisites
+RUN apk update && apk add git
+
 # build yosoy
 ADD . /go/yosoy
+RUN go env -w GOPROXY=direct
 RUN cd /go/yosoy && go build
 
-FROM alpine:3.16.2
+FROM alpine:3.18
 COPY --from=builder /go/yosoy/yosoy /bin
 
 # register entrypoint

README.md

@@ -1,15 +1,18 @@
 # yosoy ![Go](https://github.com/lukaszbudnik/yosoy/workflows/Go/badge.svg) ![Docker](https://github.com/lukaszbudnik/yosoy/workflows/Docker%20Image%20CI/badge.svg)
 
-yosoy is a HTTP service for stubbing and prototyping distributed applications. It is a service which will introduce itself to the caller and print some useful information about its environment. "Yo soy" in español means "I am".
+yosoy is an HTTP service for stubbing and prototyping distributed applications. It is a service that introduces itself to the caller and prints useful information about its runtime environment. 
 
-yosoy is extremely useful when creating a distributed application stub and you need to see more meaningful responses than a default nginx welcome page.
+yosoy is extremely useful when creating a stub for a distributed application, as it provides more meaningful responses than, for example, a default nginx welcome page. Further, yosoy incorporates a built-in reachability analyzer to facilitate troubleshooting connectivity issues in distributed systems. A dedicated reachability analyzer endpoint validates network connectivity between yosoy and remote endpoints.
 
 Typical use cases include:
 
-- testing HTTP routing & ingress
+- Testing HTTP routing and ingress
-- testing HTTP load balancing
+- Testing HTTP load balancing
-- testing HTTP caching
+- Testing HTTP caching
-- stubbing and prototyping distributed applications
+- Executing reachability analysis
+- Stubbing and prototyping distributed applications
+
+"Yo soy" means "I am" in Spanish.
 
 ## API
 
@@ -31,19 +34,25 @@ yosoy responds to all requests with a JSON containing the information about:
   - Env variables if `YOSOY_SHOW_ENVS` is set to `true`, `yes`, `on`, or `1`
   - Files' contents if `YOSOY_SHOW_FILES` is set to a comma-separated list of (valid) files
 
-Checkout out [Sample JSON response](#sample-json-response) below to see how useful yosoy is when troubleshooting/stubbing/prototyping distributed applications.
+Check [Sample JSON response](#sample-json-response) to see how you can use yosoy for stubbing/prototyping/troubleshooting distributed applications.
+
+## ping/reachability analyzer
+
+yosoy includes a simple ping/reachability analyzer. You can use this functionality when prototyping distributed systems to validate whether a given component can reach a specific endpoint. yosoy exposes a dedicated `/_/yosoy/ping` endpoint which accepts the following 4 query parameters:
+
+* `h` - required - hostname of the endpoint
+* `p` - required - port of the endpoint
+* `n` - optional - network, all valid Go networks are supported (including the most popular ones like `tcp`, `udp`, IPv4, IPV6, etc.). If `n` parameter is not provided, it defaults to `tcp`. If `n` parameter is set to unknown network, an error will be returned.
+* `t` - optional - timeout in seconds. If `t` parameter is not provided, it defaults to `10`. If `t` contains invalid integer literal, an error will be returned.
+
+Check [Sample ping/reachability analyzer responses](#sample-pingreachability-analyzer-responses) to see how you can use yosoy for troubleshooting network connectivity.
 
 ## Docker image
 
-The docker image is available on docker hub:
+The docker image is available on docker hub and ghcr.io:
 
 ```sh
 docker pull lukasz/yosoy
-```
-
-and ghcr.io:
-
-```sh
 docker pull ghcr.io/lukaszbudnik/yosoy
 ```
 
@@ -51,7 +60,7 @@ It exposes HTTP service on port 80.
 
 ## Kubernetes example
 
-There is a sample Kubernetes deployment file in the `test` folder. It uses both `YOSOY_SHOW_ENVS` and `YOSOY_SHOW_FILES`. The deployment uses Kubernetes Downward API to expose labels and annotations as volume files which are then returned by yosoy.
+There is a sample Kubernetes deployment file in the `test` folder. It uses both `YOSOY_SHOW_ENVS` and `YOSOY_SHOW_FILES` features. The deployment uses Kubernetes Downward API to expose labels and annotations as volume files which are then returned by yosoy.
 
 Deploy it to minikube and execute curl to the service a couple of times:
 
@@ -131,3 +140,58 @@ A sample yosoy JSON response to a request made from a single page application (S
   }
 }
 ```
+
+## Sample ping/reachability analyzer responses
+
+To test if yosoy can connect to `google.com` on port `443` using default `tcp` network use the following command:
+
+```bash
+curl -v "http://localhost/_/yosoy/ping?h=google.com&p=443"
+> GET /_/yosoy/ping?h=google.com&p=443 HTTP/1.1
+> Host: localhost
+> User-Agent: curl/7.86.0
+> Accept: */*
+>
+< HTTP/1.1 200 OK
+< Date: Fri, 17 Nov 2023 05:54:36 GMT
+< Content-Length: 29
+< Content-Type: text/plain; charset=utf-8
+<
+{"message":"ping succeeded"}
+```
+
+To see an unsuccessful response you may use localhost with some random port number:
+
+```bash
+curl -v "http://localhost/_/yosoy/ping?h=127.0.0.1&p=12345"
+> GET /_/yosoy/ping?h=127.0.0.1&p=12345 HTTP/1.1
+> Host: localhost
+> User-Agent: curl/7.86.0
+> Accept: */*
+>
+< HTTP/1.1 500 Internal Server Error
+< Date: Fri, 17 Nov 2023 05:53:48 GMT
+< Content-Length: 66
+< Content-Type: text/plain; charset=utf-8
+<
+{"error":"dial tcp 127.0.0.1:12345: connect: connection refused"}
+```
+
+## Building and testing locally
+
+Here are some commands to get you started.
+
+Run yosoy directly on port 80.
+
+```bash
+go test -coverprofile cover.out
+go tool cover -html=cover.out
+go run server.go
+```
+
+Building local Docker container and run it on port 8080:
+
+```bash
+docker build -t yosoy-local:latest .
+docker run --rm --name yosoy-local -p 8080:80 yosoy-local:latest
+```

go.mod

@@ -1,9 +1,16 @@
 module github.com/lukaszbudnik/yosoy
 
-go 1.16
+go 1.21
 
 require (
-	github.com/gorilla/handlers v1.5.1
+	github.com/gorilla/handlers v1.5.2
-	github.com/gorilla/mux v1.8.0
+	github.com/gorilla/mux v1.8.1
-	github.com/stretchr/testify v1.8.0
+	github.com/stretchr/testify v1.8.4
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/felixge/httpsnoop v1.0.3 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,21 +1,16 @@
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
+github.com/felixge/httpsnoop v1.0.3 h1:s/nj+GCswXYzN5v2DpNMuMQYe+0DDwt5WVCU6CWBdXk=
-github.com/felixge/httpsnoop v1.0.1/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/felixge/httpsnoop v1.0.3/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
-github.com/gorilla/handlers v1.5.1 h1:9lRY6j8DEeeBT10CvO9hGW0gmky0BprnvDI5vfhUHH4=
+github.com/gorilla/handlers v1.5.2 h1:cLTUSsNkgcwhgRqvCNmdbRWG0A3N4F+M2nWKdScwyEE=
-github.com/gorilla/handlers v1.5.1/go.mod h1:t8XrUpc4KVXb7HGyJ4/cEnwQiaxrX/hz1Zv/4g96P1Q=
+github.com/gorilla/handlers v1.5.2/go.mod h1:dX+xVpaxdSw+q0Qek8SSsl3dfMk3jNddUkMzo0GtH0w=
-github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.1 h1:TuBL49tXwgrFYWhqrNgrUNEY92u81SPhu7sTdzQEiWY=
-github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/gorilla/mux v1.8.1/go.mod h1:AKf9I4AEqPTmMytcMc0KkNouC66V3BtZ4qD5fmWSiMQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 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=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
-github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
-github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

server.go

@@ -2,16 +2,21 @@ package main
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
 )
 
+const PING_DEFAULT_TIMEOUT = 10
+const PING_DEFAULT_NETWORK = "tcp"
+
 type response struct {
 	Host         string              `json:"host"`
 	Proto        string              `json:"proto"`
@@ -27,6 +32,14 @@ type response struct {
 	Files        map[string]string   `json:"files,omitempty"`
 }
 
+type errorResponse struct {
+	Error string `json:"error"`
+}
+
+type successResponse struct {
+	Message string `json:"message"`
+}
+
 var counter = 0
 var hostname = os.Getenv("HOSTNAME")
 
@@ -71,7 +84,7 @@ func handler(w http.ResponseWriter, req *http.Request) {
 		response.Files = make(map[string]string)
 		files := strings.Split(showFiles, ",")
 		for _, file := range files {
-			bytes, err := ioutil.ReadFile(file)
+			bytes, err := os.ReadFile(file)
 			if err != nil {
 				log.Printf("Could not read file %v: %v\n", file, err)
 				continue
@@ -86,6 +99,73 @@ func handler(w http.ResponseWriter, req *http.Request) {
 	json.NewEncoder(w).Encode(response)
 }
 
+func ping(w http.ResponseWriter, req *http.Request) {
+	// get h, p, n, t parameters from query string
+	hostname := req.URL.Query().Get("h")
+	port := req.URL.Query().Get("p")
+	network := req.URL.Query().Get("n")
+	timeoutString := req.URL.Query().Get("t")
+	var timeout int64 = PING_DEFAULT_TIMEOUT
+
+	// return HTTP BadRequest when hostname is empty
+	if hostname == "" {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Header().Add("Content-Type", "application/json; charset=utf-8")
+		json.NewEncoder(w).Encode(&errorResponse{"hostname is empty"})
+		return
+	}
+	// return HTTP BadRequest when port is empty
+	if port == "" {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Header().Add("Content-Type", "application/json; charset=utf-8")
+		json.NewEncoder(w).Encode(&errorResponse{"port is empty"})
+		return
+	}
+	// check if timeoutString is a valid int64, return HTTP BadRequest when invalid, otherwise set timeout value
+	if timeoutString != "" {
+		timeoutInt, err := strconv.ParseInt(timeoutString, 10, 64)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Header().Add("Content-Type", "application/json; charset=utf-8")
+			json.NewEncoder(w).Encode(&errorResponse{"timeout is invalid"})
+			return
+		}
+		timeout = timeoutInt
+	}
+
+	// if network is empty set default to tcp
+	if network == "" {
+		network = PING_DEFAULT_NETWORK
+	}
+
+	// ping the hostname and port
+	err := pingHost(hostname, port, network, timeout)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Add("Content-Type", "application/json; charset=utf-8")
+		json.NewEncoder(w).Encode(&errorResponse{err.Error()})
+		return
+	}
+	// return HTTP OK
+	w.WriteHeader(http.StatusOK)
+	w.Header().Add("Content-Type", "application/json; charset=utf-8")
+	json.NewEncoder(w).Encode(&successResponse{"ping succeeded"})
+}
+
+func pingHost(hostname, port, network string, timeout int64) error {
+	// create timeoutDuration variable of Duration type using timeout as the value in seconds
+	timeoutDuration := time.Duration(timeout) * time.Second
+
+	// open a socket to hostname and port
+	conn, err := net.DialTimeout(network, hostname+":"+port, timeoutDuration)
+	if err != nil {
+		return err
+	}
+	// close the socket
+	conn.Close()
+	return nil
+}
+
 func remoteAddrWithoutPort(req *http.Request) string {
 	remoteAddr := req.RemoteAddr
 	if index := strings.LastIndex(remoteAddr, ":"); index > 0 {
@@ -100,6 +180,7 @@ func main() {
 	r := mux.NewRouter()
 
 	r.Handle("/favicon.ico", r.NotFoundHandler)
+	r.HandleFunc("/_/yosoy/ping", ping).Methods(http.MethodGet)
 	r.PathPrefix("/").HandlerFunc(preflight).Methods(http.MethodOptions)
 	r.PathPrefix("/").HandlerFunc(handler).Methods(http.MethodGet, http.MethodPut, http.MethodPatch, http.MethodPost, http.MethodDelete, http.MethodConnect, http.MethodHead, http.MethodTrace)
 

server_test.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -12,7 +14,7 @@ import (
 
 func TestHandler(t *testing.T) {
 	os.Setenv("YOSOY_SHOW_ENVS", "true")
-	os.Setenv("YOSOY_SHOW_FILES", ".gitignore")
+	os.Setenv("YOSOY_SHOW_FILES", ".gitignore,/file/does/not/exist")
 
 	req, err := http.NewRequest("GET", "https://example.org/sample/path?one=jeden&two=dwa", nil)
 	if err != nil {
@@ -29,8 +31,12 @@ func TestHandler(t *testing.T) {
 		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusOK)
 	}
 
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
 	var response response
-	json.Unmarshal(rr.Body.Bytes(), &response)
+	json.Unmarshal(buf.Bytes(), &response)
 
 	// test response
 	assert.Equal(t, 1, response.Counter)
@@ -43,5 +49,257 @@ func TestHandler(t *testing.T) {
 	assert.NotEmpty(t, response.Files[".gitignore"])
 
 	// test cors
-	assert.Contains(t, rr.HeaderMap["Access-Control-Allow-Origin"], "*")
+	assert.Contains(t, result.Header["Access-Control-Allow-Origin"], "*")
+}
+
+// write test for request /_/yosoy/ping without any query parameters, the request should return bad request 400 error and return JSON error about missing hostname parameter
+func TestHandlerPingNoParameters(t *testing.T) {
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusBadRequest {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusBadRequest)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
+	var response errorResponse
+	json.Unmarshal(buf.Bytes(), &response)
+
+	// test response
+	assert.Equal(t, "hostname is empty", response.Error)
+}
+
+// write test for request /_/yosoy/ping with h parameter, the request should return bad request 400 error and return JSON error about port is empty
+func TestHandlerPingWithHostname(t *testing.T) {
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=example.org", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusBadRequest {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusBadRequest)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
+	var response errorResponse
+	json.Unmarshal(buf.Bytes(), &response)
+
+	// test response
+	assert.Equal(t, "port is empty", response.Error)
+}
+
+// write test for request /_/yosoy/ping with h=127.0.0.1 parameter and p=8123 parameter, the request should return bad request 400 error and return JSON error about tcp connection issue
+func TestHandlerPingWithHostnameAndPort(t *testing.T) {
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=127.0.0.1&p=8123", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusInternalServerError {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusInternalServerError)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
+	var response errorResponse
+	json.Unmarshal(buf.Bytes(), &response)
+
+	// test response
+	assert.Equal(t, "dial tcp 127.0.0.1:8123: connect: connection refused", response.Error)
+}
+
+// write test for request /_/yosoy/ping with h=127.0.0.1 parameter and p=8123 parameter, the request should return 200 ok and return JSON with message ping succeeded
+func TestHandlerPingWithHostnameAndPortSuccess(t *testing.T) {
+
+	// create tcp process to listen on port 8123
+	listener, err := net.Listen("tcp", "localhost:8123")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=127.0.0.1&p=8123", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	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)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
+	var response successResponse
+	json.Unmarshal(buf.Bytes(), &response)
+
+	// test response
+	assert.Equal(t, "ping succeeded", response.Message)
+}
+
+// write test for request /_/yosoy/ping?h=127.0.0.1&p=8123&n=qwq, the request should return 500 internal server error and return JSON with error "dial qwq: unknown network qwq"
+func TestHandlerPingWithHostnameAndPortAndNetwork(t *testing.T) {
+
+	// create tcp process to listen on port 8123
+	listener, err := net.Listen("tcp", "localhost:8123")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=127.0.0.1&p=8123&n=qwq", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusInternalServerError {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusInternalServerError)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+	var response errorResponse
+	json.Unmarshal(buf.Bytes(), &response)
+	// test response
+	assert.Equal(t, "dial qwq: unknown network qwq", response.Error)
+}
+
+// write test for preflight HTTP Options request, verify that all headers are set
+func TestHandlerPreflight(t *testing.T) {
+	req, err := http.NewRequest("OPTIONS", "https://example.org/test", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(preflight)
+
+	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)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+
+	// test response
+	assert.Equal(t, "*", result.Header.Get("Access-Control-Allow-Origin"))
+	assert.Equal(t, "*", result.Header.Get("Access-Control-Allow-Methods"))
+	assert.Equal(t, "*", result.Header.Get("Access-Control-Allow-Headers"))
+	assert.Equal(t, "true", result.Header.Get("Access-Control-Allow-Credentials"))
+	assert.Equal(t, "600", result.Header.Get("Access-Control-Max-Age"))
+	assert.Equal(t, "*", result.Header.Get("Access-Control-Expose-Headers"))
+}
+
+// write test for request /_/yosoy/ping?h=127.0.0.1&p=8123&n=tcp&t=5, the request should return 200 ok and return JSON with message "ping succeeded"
+func TestHandlerPingWithHostnameAndPortAndNetworkAndTimeout(t *testing.T) {
+
+	// create tcp process to listen on port 8123
+	listener, err := net.Listen("tcp", "localhost:8123")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=127.0.0.1&p=8123&n=tcp&t=5", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	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)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+	var response successResponse
+	json.Unmarshal(buf.Bytes(), &response)
+	// test response
+	assert.Equal(t, "ping succeeded", response.Message)
+}
+
+// write test for request /_/yosoy/ping?h=127.0.0.1&p=8123&n=tcp&t=invalid, the request should return 400 bad request and return JSON with error "timeout is invalid"
+func TestHandlerPingWithHostnameAndPortAndNetworkAndTimeoutInvalid(t *testing.T) {
+
+	// create tcp process to listen on port 8123
+	listener, err := net.Listen("tcp", "localhost:8123")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+
+	req, err := http.NewRequest("GET", "https://example.org/_/yosoy/ping?h=127.0.0.1&p=8123&n=tcp&t=invalid", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Header.Set("Accept", "*/*")
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(ping)
+
+	handler.ServeHTTP(rr, req)
+
+	if status := rr.Code; status != http.StatusBadRequest {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusBadRequest)
+	}
+
+	result := rr.Result()
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(result.Body)
+	var response errorResponse
+	json.Unmarshal(buf.Bytes(), &response)
+	// test response
+	assert.Equal(t, "timeout is invalid", response.Error)
 }

test/deployment.yaml

@@ -16,7 +16,7 @@ spec:
     spec:
       containers:
       - name: yosoy
-        image: lukasz/yosoy:2.0.3
+        image: lukasz/yosoy:edge
         env:
           - name: YOSOY_SHOW_ENVS
             value: "true"