Honor the Retry-After HTTP header in case of 413 status code.

Issue-ID: DCAEGEN2-1483
Signed-off-by: tkogut <tomasz.kogut@nokia.com>
Change-Id: I429474d4a0565f5aa9bd542daa0db814c5504ef6

15 files changed, 464 insertions, 45 deletions

diff --git a/Changelog.md b/Changelog.md
index 619ed7ba..bfaeb9f5 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -4,10 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).    
 
-## [1.7.0] - 10/02/2021
+## [1.7.0] - 25/02/2021
 ### Added
     - [DCAEGEN2-1483] (https://jira.onap.org/browse/DCAEGEN2-1483) - VESCollector Event ordering
         - Add possibility to modify the configuration for persistent connection
+        - Support retry-after header in DCAE-SDK DMaaP-Client
      
 ## [1.6.0] ##
     - Add configurable timeout in dmaap-client
diff --git a/rest-services/cbs-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/cbs/client/impl/CbsClientImplTest.java b/rest-services/cbs-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/cbs/client/impl/CbsClientImplTest.java
index 40cf7100..c9f92717 100644
--- a/rest-services/cbs-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/cbs/client/impl/CbsClientImplTest.java
+++ b/rest-services/cbs-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/cbs/client/impl/CbsClientImplTest.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START====================================
  * DCAEGEN2-SERVICES-SDK
  * =========================================================
- * Copyright (C) 2019 Nokia. All rights reserved.
+ * Copyright (C) 2019-2021 Nokia. All rights reserved.
  * =========================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@
 package org.onap.dcaegen2.services.sdk.rest.services.cbs.client.impl;
 
 import com.google.gson.JsonObject;
+import io.vavr.collection.HashMultimap;
 import org.junit.jupiter.api.Test;
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpMethod;
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpRequest;
@@ -58,6 +59,7 @@ class CbsClientImplTest {
                 .url("http://xxx")
                 .statusCode(200)
                 .rawBody("{}".getBytes())
+                .headers(HashMultimap.withSeq().empty())
                 .build();
         given(httpClient.call(any(HttpRequest.class))).willReturn(Mono.just(httpResponse));
         RequestDiagnosticContext diagnosticContext = RequestDiagnosticContext.create();
@@ -74,4 +76,4 @@ class CbsClientImplTest {
                 .build());
         assertThat(result.toString()).isEqualTo(httpResponse.bodyAsString());
     }
-}
\ No newline at end of file
+}
diff --git a/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterPublisherImplTest.java b/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterPublisherImplTest.java
index 2fde441d..6c6ded16 100644
--- a/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterPublisherImplTest.java
+++ b/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterPublisherImplTest.java
@@ -28,6 +28,7 @@ import com.google.gson.JsonPrimitive;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.handler.codec.http.HttpHeaderValues;
 import io.netty.handler.timeout.ReadTimeoutException;
+import io.vavr.collection.HashMultimap;
 import io.vavr.collection.List;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
@@ -545,6 +546,7 @@ class MessageRouterPublisherImplTest {
                 .url(TOPIC_URL)
                 .statusReason(statusReason)
                 .rawBody("[]".getBytes())
+                .headers(HashMultimap.withSeq().empty())
                 .build();
     }
 
diff --git a/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterSubscriberImplTest.java b/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterSubscriberImplTest.java
index 74b21ad6..006965c2 100644
--- a/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterSubscriberImplTest.java
+++ b/rest-services/dmaap-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/dmaap/client/impl/MessageRouterSubscriberImplTest.java
@@ -30,6 +30,7 @@ import static org.mockito.Mockito.verify;
 
 import com.google.gson.JsonSyntaxException;
 import io.netty.handler.timeout.ReadTimeoutException;
+import io.vavr.collection.HashMultimap;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 import org.onap.dcaegen2.services.sdk.model.streams.dmaap.ImmutableMessageRouterSource;
@@ -72,24 +73,28 @@ class MessageRouterSubscriberImplTest {
             .statusReason("OK")
             .url(sourceDefinition.topicUrl())
             .rawBody("[]".getBytes())
+            .headers(HashMultimap.withSeq().empty())
             .build();
     private final HttpResponse retryableHttpResponse = ImmutableHttpResponse.builder()
             .statusCode(500)
             .statusReason("Something braked")
             .url(sourceDefinition.topicUrl())
             .rawBody("[]".getBytes())
+            .headers(HashMultimap.withSeq().empty())
             .build();
     private final HttpResponse httpResponseWithWrongStatusCode = ImmutableHttpResponse.builder()
             .statusCode(301)
             .statusReason("Something braked")
             .url(sourceDefinition.topicUrl())
             .rawBody("[]".getBytes())
+            .headers(HashMultimap.withSeq().empty())
             .build();
     private final HttpResponse httpResponseWithIncorrectJson = ImmutableHttpResponse.builder()
             .statusCode(200)
             .statusReason("OK")
             .url(sourceDefinition.topicUrl())
             .rawBody("{}".getBytes())
+            .headers(HashMultimap.withSeq().empty())
             .build();
 
     @Test
diff --git a/rest-services/http-client/pom.xml b/rest-services/http-client/pom.xml
index 6b0ab0c1..4948fbdd 100644
--- a/rest-services/http-client/pom.xml
+++ b/rest-services/http-client/pom.xml
@@ -3,7 +3,7 @@
   ~ ============LICENSE_START====================================
   ~ DCAEGEN2-SERVICES-SDK
   ~ =========================================================
-  ~ Copyright (C) 2019-2020 Nokia. All rights reserved.
+  ~ Copyright (C) 2019-2021 Nokia. All rights reserved.
   ~ =========================================================
   ~ Licensed under the Apache License, Version 2.0 (the "License");
   ~ you may not use this file except in compliance with the License.
@@ -74,6 +74,11 @@
             <scope>test</scope>
         </dependency>
         <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>
             <scope>test</scope>
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/HttpResponse.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/HttpResponse.java
index ce100478..b6cc7c2d 100644
--- a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/HttpResponse.java
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/HttpResponse.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START====================================
  * DCAEGEN2-SERVICES-SDK
  * =========================================================
- * Copyright (C) 2019 Nokia. All rights reserved.
+ * Copyright (C) 2019-2021 Nokia. All rights reserved.
  * =========================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,10 +21,11 @@
 package org.onap.dcaegen2.services.sdk.rest.services.adapters.http;
 
 import com.google.gson.Gson;
-import java.nio.charset.Charset;
-import java.nio.charset.StandardCharsets;
+import io.vavr.collection.Multimap;
 import org.immutables.value.Value;
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.exceptions.HttpException;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 
 /**
  * @author <a href="mailto:piotr.jaszczyk@nokia.com">Piotr Jaszczyk</a>
@@ -39,6 +40,8 @@ public interface HttpResponse {
 
     byte[] rawBody();
 
+    Multimap<String, String> headers();
+
     @Value.Default
     default String statusReason() {
         return "";
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/NettyHttpResponse.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/NettyHttpResponse.java
index 3dcd7098..c4c8ac8d 100644
--- a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/NettyHttpResponse.java
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/NettyHttpResponse.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START====================================
  * DCAEGEN2-SERVICES-SDK
  * =========================================================
- * Copyright (C) 2019 Nokia. All rights reserved.
+ * Copyright (C) 2019-2021 Nokia. All rights reserved.
  * =========================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,9 +20,18 @@
 
 package org.onap.dcaegen2.services.sdk.rest.services.adapters.http;
 
+import io.netty.handler.codec.http.HttpHeaders;
 import io.netty.handler.codec.http.HttpResponseStatus;
 import io.netty.handler.codec.http.HttpStatusClass;
+import io.vavr.Tuple;
+import io.vavr.Tuple2;
+import io.vavr.collection.HashMultimap;
+import io.vavr.collection.Multimap;
+import reactor.netty.http.client.HttpClientResponse;
+
 import java.nio.charset.Charset;
+import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * @author <a href="mailto:piotr.jaszczyk@nokia.com">Piotr Jaszczyk</a>
@@ -32,11 +41,13 @@ class NettyHttpResponse implements HttpResponse {
 
     private final String url;
     private final HttpResponseStatus status;
+    private final HttpHeaders headers;
     private final byte[] body;
 
-    NettyHttpResponse(String url, HttpResponseStatus status, byte[] body) {
+    public NettyHttpResponse(String url, HttpClientResponse response, byte[] body) {
         this.url = url;
-        this.status = status;
+        this.status = response.status();
+        this.headers = response.responseHeaders();
         this.body = body;
     }
 
@@ -66,6 +77,14 @@ class NettyHttpResponse implements HttpResponse {
     }
 
     @Override
+    public Multimap<String, String> headers() {
+        List<Tuple2<String, String>> httpHeaders = headers.entries().stream()
+                .map(entry -> Tuple.of(entry.getKey(), entry.getValue()))
+                .collect(Collectors.toList());
+        return HashMultimap.withSeq().ofEntries(httpHeaders);
+    }
+
+    @Override
     public String bodyAsString(Charset charset) {
         return new String(body, charset);
     }
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClient.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClient.java
index d25d7469..341aaf56 100644
--- a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClient.java
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClient.java
@@ -20,23 +20,21 @@
 
 package org.onap.dcaegen2.services.sdk.rest.services.adapters.http;
 
-import io.netty.handler.codec.http.HttpResponseStatus;
-import io.vavr.collection.HashSet;
 import io.vavr.collection.Stream;
 import io.vavr.control.Option;
-import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.RetryConfig;
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.exceptions.RetryableException;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry.RetryLogic;
 import org.onap.dcaegen2.services.sdk.rest.services.model.logging.RequestDiagnosticContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import reactor.core.publisher.Mono;
+import reactor.netty.ByteBufMono;
 import reactor.netty.http.client.HttpClient;
 import reactor.netty.http.client.HttpClient.ResponseReceiver;
 import reactor.netty.http.client.HttpClientRequest;
 import reactor.netty.http.client.HttpClientResponse;
-import reactor.util.retry.Retry;
-import reactor.util.retry.RetryBackoffSpec;
 
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 /**
@@ -46,21 +44,21 @@ public class RxHttpClient {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(RxHttpClient.class);
     private final HttpClient httpClient;
-    private RetryConfig retryConfig;
+    private RetryLogic retryLogic;
 
     RxHttpClient(HttpClient httpClient) {
-        this.httpClient = httpClient;
+        this.httpClient = Objects.requireNonNull(httpClient, "httpClient must not be null");
     }
 
-    RxHttpClient(HttpClient httpClient, RetryConfig retryConfig) {
+    RxHttpClient(HttpClient httpClient, RetryLogic retryLogic) {
         this(httpClient);
-        this.retryConfig = retryConfig;
+        this.retryLogic = retryLogic;
     }
 
     public Mono<HttpResponse> call(HttpRequest request) {
         Mono<HttpResponse> httpResponseMono = response(request);
-        return Option.of(retryConfig)
-                .map(rc -> retryConfig(rc, request.diagnosticContext()))
+        return Option.of(retryLogic)
+                .map(rc -> rc.retry(request.diagnosticContext()))
                 .map(httpResponseMono::retryWhen)
                 .getOrElse(() -> httpResponseMono);
     }
@@ -80,13 +78,13 @@ public class RxHttpClient {
 
     private Mono<HttpResponse> response(HttpRequest request) {
         return prepareRequest(request)
-                .responseSingle((resp, content) -> mapResponse(request.url(), resp.status(), content));
+                .responseSingle((resp, content) -> mapResponse(request.url(), resp, content));
     }
 
-    private Mono<HttpResponse> mapResponse(String url, HttpResponseStatus status, reactor.netty.ByteBufMono content) {
+    private Mono<HttpResponse> mapResponse(String url, HttpClientResponse response, ByteBufMono content) {
         return content.asByteArray()
                 .defaultIfEmpty(new byte[0])
-                .map(bytes -> new NettyHttpResponse(url, status, bytes))
+                .map(bytes -> new NettyHttpResponse(url, response, bytes))
                 .map(this::validatedResponse);
     }
 
@@ -98,10 +96,9 @@ public class RxHttpClient {
     }
 
     private boolean shouldRetry(int code) {
-        return Option.of(retryConfig)
-                .map(RetryConfig::retryableHttpResponseCodes)
-                .getOrElse(HashSet::empty)
-                .contains(code);
+        return Option.of(retryLogic)
+                .map(rc -> rc.shouldRetry(code))
+                .getOrElse(Boolean.FALSE);
     }
 
     private ResponseReceiver<?> prepareBody(HttpRequest request, HttpClient theClient) {
@@ -153,19 +150,4 @@ public class RxHttpClient {
         context.withSlf4jMdc(LOGGER.isDebugEnabled(),
                 () -> LOGGER.debug("Response status: {}", httpClientResponse.status()));
     }
-
-    private RetryBackoffSpec retryConfig(RetryConfig retryConfig, RequestDiagnosticContext context) {
-        return Retry
-                .fixedDelay(retryConfig.retryCount(), retryConfig.retryInterval())
-                .doBeforeRetry(retrySignal -> context.withSlf4jMdc(
-                        LOGGER.isTraceEnabled(), () -> LOGGER.trace("Retry: {}", retrySignal)))
-                .filter(ex -> isRetryable(retryConfig, ex))
-                .onRetryExhaustedThrow((retryBackoffSpec, retrySignal) -> retrySignal.failure());
-    }
-
-    private boolean isRetryable(RetryConfig retryConfig, Throwable ex) {
-        return retryConfig.retryableExceptions()
-                .toStream()
-                .exists(clazz -> clazz.isAssignableFrom(ex.getClass()));
-    }
 }
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClientFactory.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClientFactory.java
index 90b8ff16..8634f146 100644
--- a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClientFactory.java
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/RxHttpClientFactory.java
@@ -22,6 +22,7 @@ package org.onap.dcaegen2.services.sdk.rest.services.adapters.http;
 
 import io.vavr.control.Option;
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.RxHttpClientConfig;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry.RetryLogicFactory;
 import org.onap.dcaegen2.services.sdk.security.ssl.SecurityKeys;
 import org.onap.dcaegen2.services.sdk.security.ssl.TrustStoreKeys;
 import reactor.netty.http.client.HttpClient;
@@ -81,7 +82,7 @@ public final class RxHttpClientFactory {
 
     private static RxHttpClient createWithConfig(HttpClient httpClient, RxHttpClientConfig config) {
         return Option.of(config.retryConfig())
-                .map(retryConfig -> new RxHttpClient(httpClient, retryConfig))
+                .map(retryConfig -> new RxHttpClient(httpClient, RetryLogicFactory.create(retryConfig)))
                 .getOrElse(() -> new RxHttpClient(httpClient));
     }
 }
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/exceptions/RetryableException.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/exceptions/RetryableException.java
index aa48497a..6d286a6f 100644
--- a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/exceptions/RetryableException.java
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/exceptions/RetryableException.java
@@ -22,12 +22,14 @@ package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.exceptions;
 
 import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpResponse;
 
+import java.util.Objects;
+
 public class RetryableException extends RuntimeException {
 
     private final HttpResponse response;
 
     public RetryableException(HttpResponse response) {
-        this.response = response;
+        this.response = Objects.requireNonNull(response, "response must not be null");
     }
 
     public HttpResponse getResponse() {
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryIntervalExtractor.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryIntervalExtractor.java
new file mode 100644
index 00000000..0e2c875a
--- /dev/null
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryIntervalExtractor.java
@@ -0,0 +1,59 @@
+/*
+ * ============LICENSE_START====================================
+ * DCAEGEN2-SERVICES-SDK
+ * =========================================================
+ * Copyright (C) 2021 Nokia. All rights reserved.
+ * =========================================================
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================
+ */
+
+package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry;
+
+import io.netty.handler.codec.http.HttpHeaderNames;
+import io.netty.handler.codec.http.HttpResponseStatus;
+import io.vavr.Tuple;
+import io.vavr.Value;
+import io.vavr.collection.Multimap;
+import io.vavr.control.Option;
+import io.vavr.control.Try;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpResponse;
+
+import java.time.Duration;
+
+class RetryIntervalExtractor {
+
+    private static final String RETRY_AFTER_HEADER = HttpHeaderNames.RETRY_AFTER.toString();
+    private static final int PAYLOAD_TOO_LARGE_HTTP_CODE = HttpResponseStatus.REQUEST_ENTITY_TOO_LARGE.code();
+
+    Option<Duration> extractDelay(HttpResponse response) {
+        return response.statusCode() == PAYLOAD_TOO_LARGE_HTTP_CODE
+                ? extractDelay(response.headers())
+                : Option.none();
+    }
+
+    private Option<Duration> extractDelay(Multimap<String, String> headers) {
+        return headers
+                .map((key, value) -> Tuple.of(key.toLowerCase(), value))
+                .get(RETRY_AFTER_HEADER)
+                .toStream()
+                .flatMap(Value::toStream)
+                .map(this::parse)
+                .find(d -> d >= 0)
+                .map(Duration::ofSeconds);
+    }
+
+    private int parse(String str) {
+        return Try.of(() -> Integer.parseInt(str)).getOrElse(-1);
+    }
+}
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogic.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogic.java
new file mode 100644
index 00000000..fd420843
--- /dev/null
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogic.java
@@ -0,0 +1,75 @@
+/*
+ * ============LICENSE_START====================================
+ * DCAEGEN2-SERVICES-SDK
+ * =========================================================
+ * Copyright (C) 2021 Nokia. All rights reserved.
+ * =========================================================
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================
+ */
+
+package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry;
+
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.RetryConfig;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.exceptions.RetryableException;
+import org.onap.dcaegen2.services.sdk.rest.services.model.logging.RequestDiagnosticContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import reactor.core.publisher.Mono;
+import reactor.util.retry.Retry;
+
+import java.time.Duration;
+import java.util.Objects;
+
+public class RetryLogic {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(RetryLogic.class);
+
+    private final RetryConfig retryConfig;
+    private final RetryIntervalExtractor delayExtractor;
+
+    public RetryLogic(RetryConfig retryConfig, RetryIntervalExtractor delayExtractor) {
+        this.retryConfig = Objects.requireNonNull(retryConfig, "retryConfig must not be null");
+        this.delayExtractor = Objects.requireNonNull(delayExtractor, "delayExtractor must not be null");
+    }
+
+    public Retry retry(RequestDiagnosticContext requestDiagnosticContext) {
+        return Retry
+                .max(retryConfig.retryCount())
+                .doAfterRetryAsync(rc -> Mono.delay(calculateDelay(rc.failure())).then())
+                .doBeforeRetry(retrySignal -> requestDiagnosticContext.withSlf4jMdc(
+                        LOGGER.isTraceEnabled(), () -> LOGGER.trace("Retry: {}", retrySignal)))
+                .filter(ex -> isRetryable(retryConfig, ex))
+                .onRetryExhaustedThrow((retryBackoffSpec, retrySignal) -> retrySignal.failure());
+    }
+
+    public boolean shouldRetry(int code) {
+        return retryConfig.retryableHttpResponseCodes().contains(code);
+    }
+
+    private Duration calculateDelay(Throwable tx) {
+        Duration retryInterval = retryConfig.retryInterval();
+        if (tx instanceof RetryableException) {
+            RetryableException ex = (RetryableException) tx;
+            retryInterval = delayExtractor.extractDelay(ex.getResponse())
+                    .getOrElse(retryInterval);
+        }
+        return retryInterval;
+    }
+
+    private boolean isRetryable(RetryConfig retryConfig, Throwable ex) {
+        return retryConfig.retryableExceptions()
+                .toStream()
+                .exists(clazz -> clazz.isAssignableFrom(ex.getClass()));
+    }
+}
diff --git a/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicFactory.java b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicFactory.java
new file mode 100644
index 00000000..51acbe12
--- /dev/null
+++ b/rest-services/http-client/src/main/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicFactory.java
@@ -0,0 +1,33 @@
+/*
+ * ============LICENSE_START====================================
+ * DCAEGEN2-SERVICES-SDK
+ * =========================================================
+ * Copyright (C) 2021 Nokia. All rights reserved.
+ * =========================================================
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================
+ */
+
+package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry;
+
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.RetryConfig;
+
+public final class RetryLogicFactory {
+
+    private RetryLogicFactory() {
+    }
+
+    public static RetryLogic create(RetryConfig config) {
+        return new RetryLogic(config, new RetryIntervalExtractor());
+    }
+}
diff --git a/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/DelayExtractorTest.java b/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/DelayExtractorTest.java
new file mode 100644
index 00000000..d5759b26
--- /dev/null
+++ b/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/DelayExtractorTest.java
@@ -0,0 +1,98 @@
+/*
+ * ============LICENSE_START====================================
+ * DCAEGEN2-SERVICES-SDK
+ * =========================================================
+ * Copyright (C) 2021 Nokia. All rights reserved.
+ * =========================================================
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================
+ */
+
+package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry;
+
+import io.vavr.Tuple;
+import io.vavr.collection.HashMultimap;
+import io.vavr.control.Option;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpResponse;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.ImmutableHttpResponse;
+
+import java.time.Duration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class DelayExtractorTest {
+
+    private static final HttpResponse DEFAULT = ImmutableHttpResponse.builder()
+            .url("")
+            .statusCode(0)
+            .rawBody("".getBytes())
+            .headers(HashMultimap.withSeq().empty())
+            .build();
+
+    private static final RetryIntervalExtractor DELAY_EXTRACTOR = new RetryIntervalExtractor();
+
+    @Test
+    void shouldExtractValueFromFirstValidHeaderWhenStatusCode413() {
+        // given
+        HttpResponse response = ImmutableHttpResponse.copyOf(DEFAULT)
+                .withStatusCode(413)
+                .withHeaders(HashMultimap.withSeq().ofEntries(
+                        Tuple.of("Any", "12"),
+                        Tuple.of("Retry-After", "15"),
+                        Tuple.of("Retry-After", "100")
+                ));
+
+        // when
+        Option<Duration> delay = DELAY_EXTRACTOR.extractDelay(response);
+
+        // then
+        assertThat(delay.get()).isEqualTo(Duration.ofSeconds(15));
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = {100, 200, 300, 400, 500})
+    void shouldExtractNoValueWhenStatusCodeDifferentThan413(int statusCode) {
+        // given
+        HttpResponse response = ImmutableHttpResponse.copyOf(DEFAULT)
+                .withStatusCode(statusCode);
+
+        // when
+        Option<Duration> delay = DELAY_EXTRACTOR.extractDelay(response);
+
+        // then
+        assertThat(delay).isEqualTo(Option.none());
+    }
+
+    @ParameterizedTest
+    @CsvSource({
+            "Retry-After,",
+            "Retry-After,invalid",
+            "Retry-After,999999999999",
+            "Any,12"})
+    void shouldExtractNoValueWhenStatusCode413AndNoValidHeader(String key, String value) {
+        // given
+        HttpResponse response = ImmutableHttpResponse.copyOf(DEFAULT)
+                .withStatusCode(413)
+                .withHeaders(HashMultimap.withSeq().ofEntries(Tuple.of(key, value)));
+
+        // when
+        Option<Duration> delay = DELAY_EXTRACTOR.extractDelay(response);
+
+        // then
+        assertThat(delay).isEqualTo(Option.none());
+    }
+}
diff --git a/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicTest.java b/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicTest.java
new file mode 100644
index 00000000..8319d3ae
--- /dev/null
+++ b/rest-services/http-client/src/test/java/org/onap/dcaegen2/services/sdk/rest/services/adapters/http/retry/RetryLogicTest.java
@@ -0,0 +1,132 @@
+/*
+ * ============LICENSE_START====================================
+ * DCAEGEN2-SERVICES-SDK
+ * =========================================================
+ * Copyright (C) 2021 Nokia. All rights reserved.
+ * =========================================================
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================
+ */
+
+package org.onap.dcaegen2.services.sdk.rest.services.adapters.http.retry;
+
+import io.netty.handler.timeout.ReadTimeoutException;
+import io.vavr.collection.HashMultimap;
+import io.vavr.collection.HashSet;
+import io.vavr.control.Option;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.HttpResponse;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.ImmutableHttpResponse;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.ImmutableRetryConfig;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.config.RetryConfig;
+import org.onap.dcaegen2.services.sdk.rest.services.adapters.http.exceptions.RetryableException;
+import org.onap.dcaegen2.services.sdk.rest.services.model.logging.RequestDiagnosticContext;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import java.net.ConnectException;
+import java.time.Duration;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class RetryLogicTest {
+
+    private static final HashSet<Integer> RETRYABLE_HTTP_RESPONSE_CODES =
+            HashSet.of(404, 408, 413, 429, 500, 502, 503, 504);
+    private static final HashSet<Class<? extends Throwable>> RETRYABLE_EXCEPTIONS =
+            HashSet.of(ReadTimeoutException.class, ConnectException.class);
+    private static final Duration RETRY_INTERVAL = Duration.ofSeconds(5);
+    private static final int RETRY_COUNT = 3;
+    private static final Duration RETRY_EXHAUSTED = Duration.ofSeconds(RETRY_COUNT * RETRY_INTERVAL.getSeconds());
+    private static final RetryConfig RETRY_CONFIG = ImmutableRetryConfig.builder()
+            .retryCount(RETRY_COUNT)
+            .retryInterval(RETRY_INTERVAL)
+            .retryableHttpResponseCodes(RETRYABLE_HTTP_RESPONSE_CODES)
+            .customRetryableExceptions(RETRYABLE_EXCEPTIONS)
+            .build();
+
+    private final RequestDiagnosticContext dummyContext = mock(RequestDiagnosticContext.class);
+    private final RetryIntervalExtractor retryIntervalExtractor = mock(RetryIntervalExtractor.class);
+    private RetryLogic retryLogic;
+
+    @BeforeEach
+    void setUp() {
+        retryLogic = new RetryLogic(RETRY_CONFIG, retryIntervalExtractor);
+    }
+
+    @Test
+    void shouldRetryWhenRetryableException() {
+        // when
+        Mono<?> mono = Mono
+                .error(ReadTimeoutException.INSTANCE)
+                .retryWhen(retryLogic.retry(dummyContext));
+
+        // then
+        StepVerifier.withVirtualTime(() -> mono)
+                .expectSubscription()
+                .expectNoEvent(RETRY_EXHAUSTED)
+                .expectError(ReadTimeoutException.class)
+                .verify();
+    }
+
+    @Test
+    void shouldNotRetryWhenUnretryableException() {
+        // when
+        Mono<?> mono = Mono
+                .error(RuntimeException::new)
+                .retryWhen(retryLogic.retry(dummyContext));
+
+        // then
+        StepVerifier.withVirtualTime(() -> mono)
+                .expectSubscription()
+                .expectError(RuntimeException.class)
+                .verify();
+    }
+
+    @Test
+    void shouldUseRetryIntervalFromExtractorWhenRetryableStatusCode() {
+        // given
+        HttpResponse httpResponse = httpResponse413();
+        Duration retryInterval = Duration.ofSeconds(10);
+        when(retryIntervalExtractor.extractDelay(httpResponse))
+                .thenReturn(Option.of(retryInterval));
+
+        // when
+        Mono<?> mono = Mono
+                .error(() -> new RetryableException(httpResponse))
+                .retryWhen(retryLogic.retry(dummyContext));
+
+        // then
+        long noEvents = RETRY_COUNT * retryInterval.getSeconds();
+        StepVerifier.withVirtualTime(() -> mono)
+                .expectSubscription()
+                .expectNoEvent(Duration.ofSeconds(noEvents))
+                .expectError(RetryableException.class)
+                .verify();
+        verify(retryIntervalExtractor, times(RETRY_COUNT)).extractDelay(httpResponse);
+    }
+
+    private ImmutableHttpResponse httpResponse413() {
+        return ImmutableHttpResponse.builder()
+                .url("")
+                .statusCode(413)
+                .rawBody("".getBytes())
+                .headers(HashMultimap.withSeq().empty())
+                .build();
+    }
+
+}