CDPCP-13131 - Implement an exponential backoff in the Cloudera Terraf…

…orm provider

cdp-sdk-go/cdp/backoff.go

@@ -0,0 +1,51 @@
+// Copyright 2024 Cloudera. All Rights Reserved.
+//
+// This file is licensed under the Apache License Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, either express or implied. Refer to the License for the specific
+// permissions and limitations governing your use of the file.
+
+package cdp
+
+import (
+	"log"
+	"math"
+	"math/rand"
+	"os"
+	"time"
+)
+
+const (
+	expDeltaMin = 0.75
+	expDeltaMax = 1.0
+)
+
+func backoff(retries int) time.Duration {
+	switch os.Getenv("CDP_TF_BACKOFF_STRATEGY") {
+	case "linear":
+		{
+			step := intFromEnvOrDefault("CDP_TF_BACKOFF_STEP", defaultLinearBackoffStep)
+			log.Default().Println("Using linear backoff strategy with step: ", step)
+			return linearBackoff(retries, step)
+		}
+	default:
+		{
+			log.Default().Println("Using exponential backoff strategy")
+			return exponentialBackoff(retries)
+		}
+	}
+}
+
+func exponentialBackoff(retries int) time.Duration {
+	rndSrc := rand.NewSource(time.Now().UnixNano())
+	delta := expDeltaMax - expDeltaMin
+	jitter := expDeltaMin + rand.New(rndSrc).Float64()*(delta)
+	return time.Duration((math.Pow(2, float64(retries))*jitter)*float64(time.Millisecond)) * 1000
+}
+
+func linearBackoff(retries int, step int) time.Duration {
+	return time.Duration((retries+1)*step) * time.Second
+}

cdp-sdk-go/cdp/backoff_test.go

@@ -0,0 +1,144 @@
+// Copyright 2024 Cloudera. All Rights Reserved.
+//
+// This file is licensed under the Apache License Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, either express or implied. Refer to the License for the specific
+// permissions and limitations governing your use of the file.
+
+package cdp
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func TestLinearBackoffWithPositiveRetries(t *testing.T) {
+	retries := 3
+	step := 2
+	expected := 8 * time.Second
+
+	result := linearBackoff(retries, step)
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestLinearBackoffWithZeroRetries(t *testing.T) {
+	retries := 0
+	step := 2
+	expected := 2 * time.Second
+
+	result := linearBackoff(retries, step)
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestLinearBackoffWithNegativeRetries(t *testing.T) {
+	retries := -1
+	step := 2
+	expected := 0 * time.Second
+
+	result := linearBackoff(retries, step)
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestLinearBackoffWithLargeStep(t *testing.T) {
+	retries := 2
+	step := 1000
+	expected := 3000 * time.Second
+
+	result := linearBackoff(retries, step)
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestExponentialBackoffWithPositiveRetries(t *testing.T) {
+	retries := 3
+	expectedMin := 6 * time.Second
+	expectedMax := 8 * time.Second
+
+	result := exponentialBackoff(retries)
+	if result < expectedMin || result > expectedMax {
+		t.Fatalf("Expected between %v and %v, got %v", expectedMin, expectedMax, result)
+	}
+}
+
+func TestExponentialBackoffWithZeroRetries(t *testing.T) {
+	retries := 0
+	expectedMin := 0.75 * float64(time.Second)
+	expectedMax := 1 * time.Second
+
+	result := exponentialBackoff(retries)
+	if result < time.Duration(int(expectedMin)) || result > expectedMax {
+		t.Fatalf("Expected between %v and %v, got %v", time.Duration(int(expectedMin)), expectedMax, result)
+	}
+}
+
+func TestExponentialBackoffWithHighRetries(t *testing.T) {
+	retries := 10
+	expectedMin := 768 * time.Second
+	expectedMax := 1024 * time.Second
+
+	result := exponentialBackoff(retries)
+	if result < expectedMin || result > expectedMax {
+		t.Fatalf("Expected between %v and %v, got %v", expectedMin, expectedMax, result)
+	}
+}
+
+func TestLinearBackoffStrategyWithDefaultStep(t *testing.T) {
+	_ = os.Setenv("CDP_TF_BACKOFF_STRATEGY", "linear")
+	defer func() {
+		_ = os.Unsetenv("CDP_TF_BACKOFF_STRATEGY")
+	}()
+
+	result := backoff(2)
+	expected := defaultLinearBackoffStep * 3 * time.Second
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestExponentialBackoffStrategyWithDefault(t *testing.T) {
+	_ = os.Unsetenv("CDP_TF_BACKOFF_STRATEGY")
+
+	result := backoff(3)
+	expectedMin := 6 * time.Second
+	expectedMax := 8 * time.Second
+	if result < expectedMin || result > expectedMax {
+		t.Fatalf("Expected between %v and %v, got %v", expectedMin, expectedMax, result)
+	}
+}
+
+func TestLinearBackoffStrategyWithCustomStep(t *testing.T) {
+	_ = os.Setenv("CDP_TF_BACKOFF_STRATEGY", "linear")
+	_ = os.Setenv("CDP_TF_BACKOFF_STEP", "5")
+	defer func() {
+		_ = os.Unsetenv("CDP_TF_BACKOFF_STRATEGY")
+		_ = os.Unsetenv("CDP_TF_BACKOFF_STEP")
+	}()
+
+	result := backoff(1)
+	expected := 10 * time.Second
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}
+
+func TestExponentialBackoffStrategyWithHighRetries(t *testing.T) {
+	_ = os.Unsetenv("CDP_TF_BACKOFF_STRATEGY")
+
+	result := backoff(10)
+	expectedMin := 768 * time.Second
+	expectedMax := 1024 * time.Second
+	if result < expectedMin || result > expectedMax {
+		t.Fatalf("Expected between %v and %v, got %v", expectedMin, expectedMax, result)
+	}
+}

cdp-sdk-go/cdp/retryable_transport.go

@@ -0,0 +1,68 @@
+// Copyright 2024 Cloudera. All Rights Reserved.
+//
+// This file is licensed under the Apache License Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, either express or implied. Refer to the License for the specific
+// permissions and limitations governing your use of the file.
+
+package cdp
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"time"
+)
+
+type RetryableTransport struct {
+	transport http.RoundTripper
+}
+
+func shouldRetry(err error, resp *http.Response) bool {
+	if err != nil {
+		return true
+	} else if resp == nil {
+		return false
+	}
+	return sliceContains(retryableStatusCodes, resp.StatusCode)
+}
+
+func drainBody(resp *http.Response) {
+	if resp != nil && resp.Body != nil {
+		_, err := io.Copy(io.Discard, resp.Body)
+		if err != nil {
+			log.Default().Println("Error while draining body: ", err)
+		}
+		defer func(Body io.ReadCloser) {
+			_ = Body.Close()
+		}(resp.Body)
+	}
+}
+
+func (t *RetryableTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	var bodyBytes []byte
+	if req.Body != nil {
+		bodyBytes, _ = io.ReadAll(req.Body)
+		req.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
+	}
+	resp, err := t.transport.RoundTrip(req)
+	retries := 0
+	retryCount := intFromEnvOrDefault("CDP_TF_CALL_RETRY_COUNT", 10)
+	for shouldRetry(err, resp) && retries < retryCount {
+		log.Default().Printf("Retrying request (caused by: %+v;%+v)\n", err, resp)
+		time.Sleep(backoff(retries))
+		drainBody(resp)
+		if req.Body != nil {
+			req.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
+		}
+		resp, err = t.transport.RoundTrip(req)
+		fmt.Printf("%v retry out of %v\n", retries+1, retryCount)
+		retries++
+	}
+	return resp, err
+}