Add fallback behavior for Posts service timeout problems

cloudnative-requestresilience/buildAndPushDockerImages.sh

@@ -1,6 +1,6 @@
 docker build --build-arg \
 jar_file=cloudnative-connectionposts/target/cloudnative-connectionposts-0.0.1-SNAPSHOT.jar \
--t cdavisafc/cloudnative-requestresilience-connectionposts:0.0.2 .
+-t cdavisafc/cloudnative-requestresilience-connectionposts:0.0.3 .
 # only connections posts has changed for this step
 #
-docker push cdavisafc/cloudnative-requestresilience-connectionposts:0.0.2
+docker push cdavisafc/cloudnative-requestresilience-connectionposts:0.0.3

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/config/CloudnativeApplication.java

@@ -12,6 +12,7 @@
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
 import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
+import org.springframework.data.redis.repository.configuration.EnableRedisRepositories;
 import org.springframework.retry.annotation.EnableRetry;
 
 
@@ -21,6 +22,7 @@
 @SpringBootApplication
 @ComponentScan(basePackages = { "com.corneliadavis.cloudnative.*" })
 @EntityScan("com.corneliadavis.cloudnative.*")
+@EnableRedisRepositories("com.corneliadavis.cloudnative.*")
 public class CloudnativeApplication {
 
 	@Value("${redis.hostname}")

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/connectionsposts/ConnectionsPostsController.java

@@ -84,13 +84,13 @@ public String getName() {
     @Value("${connectionpostscontroller.readTimeout}")
     private int readTimeout;
 
-    private StringRedisTemplate template;
+    private StringRedisTemplate stringRedisTemplate;
 
     private boolean isHealthy = true;
 
     @Autowired
     public ConnectionsPostsController(StringRedisTemplate template) {
-        this.template = template;
+        this.stringRedisTemplate = template;
     }
 
     @Autowired
@@ -117,7 +117,7 @@ public Iterable<PostSummary> getByUsername(@CookieValue(value = "userToken", req
             logger.info(utils.ipTag() + "connectionsPosts access attempt without auth token");
             response.setStatus(401);
         } else {
-            ValueOperations<String, String> ops = this.template.opsForValue();
+            ValueOperations<String, String> ops = this.stringRedisTemplate.opsForValue();
             String username = ops.get(token);
             if (username == null) {
                 logger.info(utils.ipTag() + "connectionsPosts access attempt with invalid token");

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/connectionsposts/PostResults.java

@@ -0,0 +1,30 @@
+package com.corneliadavis.cloudnative.connectionsposts;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.redis.core.RedisHash;
+
+import java.io.Serializable;
+
+@RedisHash("PostSummaries")
+public class PostResults implements Serializable {
+    @Id
+    private String ids;
+    private String summariesJson;
+
+    public PostResults (String ids, String summariesJson) {
+
+        this.ids = ids;
+        this.summariesJson = summariesJson;
+    }
+
+    public String getSummariesJson() {
+        return summariesJson;
+    }
+
+    public String getIds() {
+        return ids;
+    }
+
+
+}
+

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/connectionsposts/PostSummary.java

@@ -17,6 +17,8 @@ public PostSummary(String usersname, String title, Date date) {
         this.title = title;
     }
 
+    public PostSummary() {}
+
     public Date getDate() {
         return date;
     }
@@ -29,4 +31,15 @@ public String getTitle() {
         return title;
     }
 
+    public void setDate(Date date) {
+        this.date = date;
+    }
+
+    public void setUsersname(String usersname) {
+        this.usersname = usersname;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
 }

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/connectionsposts/PostsResultsRepository.java

@@ -0,0 +1,8 @@
+package com.corneliadavis.cloudnative.connectionsposts;
+
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface PostsResultsRepository extends CrudRepository<PostResults, String> {
+}

cloudnative-requestresilience/cloudnative-connectionposts/src/main/java/com/corneliadavis/cloudnative/connectionsposts/PostsServiceClient.java

@@ -1,22 +1,28 @@
 package com.corneliadavis.cloudnative.connectionsposts;
 
 import com.corneliadavis.cloudnative.Utils;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.ResponseEntity;
 import org.springframework.retry.annotation.Backoff;
+import org.springframework.retry.annotation.Recover;
 import org.springframework.retry.annotation.Retryable;
 import org.springframework.stereotype.Service;
 import org.springframework.web.client.HttpServerErrorException;
+import org.springframework.web.client.ResourceAccessException;
 import org.springframework.web.client.RestTemplate;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 
 @Service
 public class PostsServiceClient {
 
+    private PostsResultsRepository postResultsRepository;
+
     private static final Logger logger = LoggerFactory.getLogger(ConnectionsPostsController.class);
 
     @Value("${connectionpostscontroller.postsUrl}")
@@ -27,7 +33,12 @@ public class PostsServiceClient {
     @Autowired
     Utils utils;
 
-    @Retryable( value = Exception.class, maxAttempts = 3, backoff = @Backoff(delay = 1000))
+    @Autowired
+    public PostsServiceClient(PostsResultsRepository postResultsRepository) {
+        this.postResultsRepository = postResultsRepository;
+    }
+
+    @Retryable( value = ResourceAccessException.class, maxAttempts = 3, backoff = @Backoff(delay = 500))
     public ArrayList<PostSummary> getPosts(String ids, RestTemplate restTemplate) throws Exception {
 
         ArrayList<PostSummary> postSummaries = new ArrayList<PostSummary>();
@@ -43,11 +54,32 @@ public ArrayList<PostSummary> getPosts(String ids, RestTemplate restTemplate) th
             ConnectionsPostsController.PostResult[] posts = respPosts.getBody();
             for (int i = 0; i < posts.length; i++)
                 postSummaries.add(new PostSummary(getUsersname(posts[i].getUserId(), restTemplate), posts[i].getTitle(), posts[i].getDate()));
+            ObjectMapper objectMapper = new ObjectMapper();
+            String postSummariesJson = objectMapper.writeValueAsString(postSummaries);
+            PostResults postResults = new PostResults(ids, postSummariesJson);
+            postResultsRepository.save(postResults);
             return postSummaries;
         }
 
     }
 
+    @Recover
+    public ArrayList<PostSummary> returnCached(ResourceAccessException e, String ids, RestTemplate restTemplate) throws Exception {
+        logger.info("Failed to connect to or obtain results from Posts service - returning cached results");
+
+        PostResults postResults = postResultsRepository.findById(ids).get();
+        ObjectMapper objectMapper = new ObjectMapper();
+        ArrayList<PostSummary> postSummaries;
+        try {
+            postSummaries = objectMapper.readValue(postResults.getSummariesJson(), new TypeReference<ArrayList<PostSummary>>() {});
+        } catch (Exception ec) {
+            logger.info("Exception on deserialization " + ec.getClass() + " message = " + ec.getMessage());
+            return null;
+        }
+        return postSummaries;
+
+    }
+
     private String getUsersname(Long id, RestTemplate restTemplate) {
         String secretQueryParam = "?secret=" + utils.getConnectionsSecret();
         ResponseEntity<ConnectionsPostsController.UserResult> resp = restTemplate.getForEntity(usersUrl + id + secretQueryParam, ConnectionsPostsController.UserResult.class);

cloudnative-requestresilience/cookbook-deployment-connectionsposts.yaml

@@ -30,7 +30,7 @@ spec:
     spec:
       containers:
       - name: connectionsposts
-        image: cdavisafc/cloudnative-requestresilience-connectionposts:0.0.2
+        image: cdavisafc/cloudnative-requestresilience-connectionposts:0.0.3
 #        resources:
 #          limits:
 #            memory: "2048Mi"