feat(backup): Add backup/restore to the server

api/http/offlinegate/offlinegate.go

@@ -0,0 +1,71 @@
+package offlinegate
+
+import (
+	"log"
+	"net/http"
+	"sync"
+	"time"
+
+	httperror "github.com/portainer/libhttp/error"
+)
+
+// OfflineGate is a entity that works similar to a mutex with a signaling
+// Only the caller that have Locked an gate can unlock it, otherw will be blocked with a call to Lock.
+// Gate provides a passthrough http middleware that will wait for a locked gate to be unlocked.
+// For a safety reasons, middleware will timeout
+type OfflineGate struct {
+	lock        *sync.Mutex
+	signalingCh chan interface{}
+}
+
+// NewOfflineGate creates a new gate
+func NewOfflineGate() *OfflineGate {
+	return &OfflineGate{
+		lock: &sync.Mutex{},
+	}
+}
+
+// Lock locks readonly gate and returns a function to unlock
+func (o *OfflineGate) Lock() func() {
+	o.lock.Lock()
+	o.signalingCh = make(chan interface{})
+	return o.unlock
+}
+
+func (o *OfflineGate) unlock() {
+	if o.signalingCh == nil {
+		return
+	}
+
+	close(o.signalingCh)
+	o.signalingCh = nil
+	o.lock.Unlock()
+}
+
+// Watch returns a signaling channel.
+// Unless channel is nil, client needs to watch for a signal on a channel to know when gate is unlocked.
+// Signal channel is disposable: onced signaled, has to be disposed and acquired again.
+func (o *OfflineGate) Watch() chan interface{} {
+	return o.signalingCh
+}
+
+// WaitingMiddleware returns an http handler that waits for the gate to be unlocked before continuing
+func (o *OfflineGate) WaitingMiddleware(timeout time.Duration, next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		signalingCh := o.Watch()
+
+		if signalingCh != nil {
+			if r.Method != "GET" && r.Method != "HEAD" && r.Method != "OPTIONS" {
+				select {
+				case <-signalingCh:
+				case <-time.After(timeout):
+					log.Println("error: Timeout waiting for the offline gate to signal")
+					httperror.WriteError(w, http.StatusRequestTimeout, "Timeout waiting for the offline gate to signal", http.ErrHandlerTimeout)
+				}
+			}
+		}
+
+		next.ServeHTTP(w, r)
+
+	})
+}

api/http/offlinegate/offlinegate_test.go

@@ -0,0 +1,217 @@
+package offlinegate
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_canLockAndUnlock(t *testing.T) {
+	o := NewOfflineGate()
+
+	unlock := o.Lock()
+	unlock()
+}
+
+func Test_hasToBeUnlockedToLockAgain(t *testing.T) {
+	// scenario:
+	// 1. first routine starts and locks the gate
+	// 2. first routine starts a second and wait for the second to start
+	// 3. second start but waits for the gate to be released
+	// 4. first continues and unlocks the gate, when done
+	// 5. second be able to continue
+	// 6. second lock the gate, does the job and unlocks it
+
+	o := NewOfflineGate()
+
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	result := make([]string, 0, 2)
+	go func() {
+		unlock := o.Lock()
+		defer unlock()
+		waitForSecondToStart := sync.WaitGroup{}
+		waitForSecondToStart.Add(1)
+		go func() {
+			waitForSecondToStart.Done()
+			unlock := o.Lock()
+			defer unlock()
+			result = append(result, "second")
+			wg.Done()
+		}()
+		waitForSecondToStart.Wait()
+		result = append(result, "first")
+		wg.Done()
+	}()
+
+	wg.Wait()
+
+	if len(result) != 2 || result[0] != "first" || result[1] != "second" {
+		t.Error("Second call have disresregarded a raised lock")
+	}
+
+}
+
+func Test_waitChannelWillBeEmpty_ifGateIsUnlocked(t *testing.T) {
+	o := NewOfflineGate()
+
+	signalingCh := o.Watch()
+	if signalingCh != nil {
+		t.Error("Signaling channel should be empty")
+	}
+}
+
+func Test_startWaitingForSignal_beforeGateGetsUnlocked(t *testing.T) {
+	// scenario:
+	// 1. main routing locks the gate and waits for a consumer to start up
+	// 2. consumer starts up, notifies main and begins waiting for the gate to be unlocked
+	// 3. main unlocks the gate
+	// 4. consumer be able to continue
+
+	o := NewOfflineGate()
+	unlock := o.Lock()
+
+	signalingCh := o.Watch()
+
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+	readerIsReady := sync.WaitGroup{}
+	readerIsReady.Add(1)
+
+	go func(t *testing.T) {
+		readerIsReady.Done()
+
+		// either wait for a signal or timeout
+		select {
+		case <-signalingCh:
+		case <-time.After(10 * time.Second):
+			t.Error("Failed to wait for a signal, exit by timeout")
+		}
+		wg.Done()
+	}(t)
+
+	readerIsReady.Wait()
+	unlock()
+
+	wg.Wait()
+}
+
+func Test_startWaitingForSignal_afterGateGetsUnlocked(t *testing.T) {
+	// scenario:
+	// 1. main routing locks, gets waiting channel and unlocks
+	// 2. consumer starts up and begins waiting for the gate to be unlocked
+	// 3. consumer gets signal immediately and continues
+
+	o := NewOfflineGate()
+	unlock := o.Lock()
+	signalingCh := o.Watch()
+	unlock()
+
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+
+	go func(t *testing.T) {
+		// either wait for a signal or timeout
+		select {
+		case <-signalingCh:
+		case <-time.After(10 * time.Second):
+			t.Error("Failed to wait for a signal, exit by timeout")
+		}
+		wg.Done()
+	}(t)
+
+	wg.Wait()
+}
+
+func Test_waitingMiddleware_executesImmediately_whenNotLocked(t *testing.T) {
+	// scenario:
+	// 1. create an gate
+	// 2. kick off a waiting middleware that will release immediately as gate wasn't locked
+	// 3. middleware shouldn't timeout
+
+	o := NewOfflineGate()
+
+	request := httptest.NewRequest(http.MethodPost, "/", nil)
+	response := httptest.NewRecorder()
+
+	timeout := 2 * time.Second
+	start := time.Now()
+	o.WaitingMiddleware(timeout, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		elapsed := time.Since(start)
+		if elapsed >= timeout {
+			t.Error("WaitingMiddleware had likely timeout, when it shouldn't")
+		}
+		w.Write([]byte("success"))
+	})).ServeHTTP(response, request)
+
+	body, _ := io.ReadAll(response.Body)
+	if string(body) != "success" {
+		t.Error("Didn't receive expected result from the hanlder")
+	}
+}
+
+func Test_waitingMiddleware_waitsForTheLockToBeReleased(t *testing.T) {
+	// scenario:
+	// 1. create an gate and lock it
+	// 2. kick off a routing that will unlock the gate after 1 second
+	// 3. kick off a waiting middleware that will wait for lock to be eventually released
+	// 4. middleware shouldn't timeout
+
+	o := NewOfflineGate()
+	unlock := o.Lock()
+
+	request := httptest.NewRequest(http.MethodPost, "/", nil)
+	response := httptest.NewRecorder()
+
+	go func() {
+		time.Sleep(1 * time.Second)
+		unlock()
+	}()
+
+	timeout := 10 * time.Second
+	start := time.Now()
+	o.WaitingMiddleware(timeout, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		elapsed := time.Since(start)
+		if elapsed >= timeout {
+			t.Error("WaitingMiddleware had likely timeout, when it shouldn't")
+		}
+		w.Write([]byte("success"))
+	})).ServeHTTP(response, request)
+
+	body, _ := io.ReadAll(response.Body)
+	if string(body) != "success" {
+		t.Error("Didn't receive expected result from the hanlder")
+	}
+}
+
+func Test_waitingMiddleware_mayTimeout_whenLockedForTooLong(t *testing.T) {
+	/*
+		scenario:
+		1. create an gate and lock it
+		2. kick off a waiting middleware that will wait for lock to be eventually released
+		3. because we never unlocked the gate, middleware suppose to timeout
+	*/
+	o := NewOfflineGate()
+	o.Lock()
+
+	request := httptest.NewRequest(http.MethodPost, "/", nil)
+	response := httptest.NewRecorder()
+
+	timeout := 1 * time.Second
+	start := time.Now()
+	o.WaitingMiddleware(timeout, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		elapsed := time.Since(start)
+		if elapsed < timeout {
+			t.Error("WaitingMiddleware suppose to timeout, but it didnt")
+		}
+		w.Write([]byte("success"))
+	})).ServeHTTP(response, request)
+
+	assert.Equal(t, http.StatusRequestTimeout, response.Result().StatusCode, "Request support to timeout waiting for the gate")
+}