Microservices.pdf

Transcript

1. Microservices The introduction
2. Microservices The introduction
3. Overview What are microservices ?
4. user service product service customer service cart service payment service Monolith Database
5. user service product service customer service cart service payment service Monolith Load Balancer user service product service customer service cart service payment service Monolith Database
6. user service product service customer service cart service payment service product service customer service Communication Channel (HTTP protocol / Messaging services like RabbitMQ ,Kafka) recommendation service customer db user db cart db product db payment db
7. Advantages of Microservices Scale or fail
8. Advantages 1. Improved fault tolerance 2. Easy to understand. 3. No vendor or technology lock in 4. Easy to add new modules.
9. Drawbacks of Microservices It is not the silver bullet. :)
10. Drawbacks 1. Distributed systems are complex 2. Multiple databases makes it difficult for transactional consistency 3. Tough to test 4. Could be tough to deploy
11. Components of Microservices Scale or fail
12. Feign client ribbon sleuth hystrix user service Feign client ribbon sleuth hystrix task service config server service-discovery (eureka) RabbitMq zipkins ui API Gateway (ZUUL) user db todo db
13. user-service
14. user-service Anatomy and structure A simple microservice . Manages users
15. task-service
16. task-service Anatomy and structure A simple microservice . Create tasks Tasks can be tagged to multiple category Task can be assigned to users. Sends list of tasks and lists of task assigned to a user
17. Config Server
18. Config Server Advantages • A central place for all the configurations. • Easy to manage when number of microservices increases • Easy to track configurations changes and act in case of breaking changes due to version control
19. user service task service config server user service user service task service task service task service task service git
20. Creating config server
21. Connect to config server
22. user service task service config server user service user service task service task service task service task service git
23. Calling task-service from user-service The mess of distributed system
24. Feign - Declarative RESTful client
25. Feign A declarative REST client Helps to write clean code. Focus on business logic rather implementing REST API contracts.
26. Ribbon - The load balancer The client side load balancer
27. Ribbon The client side load balancer Load balancing is important in microservices. Ribbon a client side load balancer helps to distribute calls to multiple instances of a service
28. user service task service task service task service Ribbon Client side load balancing
29. Eureka - Service Discovery Eureka - I found it
30. Eureka Eureka - The Service is discovered • Helps to find different services • Keeps register of new instances of services going up and down
31. user service task service task service task service Ribbon ribbon.service.ur l=.http://
32. API Gateway - Zuul
33. API Gateway - Zuul • API gateway acts as single point of contact for outside services • It’s a unique gateway to client , client make calls to API gateway and gateway in turn delegate requests to required microservices. • Obviously it can be used to aggregate responses from different microservices and send a unified response. • Apart from aggregating responses it can also be used for rate limiting ,authorization and authentication ,fault tolerance and any custom filter required to be executed during a service call.
34. Distributed tracing Do you know where he went ?
35. Distributed tracing Why ? • One request often requires multiple services • Each request performs more than one task like database operation, messaging etc • Difficult to troubleshoot and understand behaviour of application
36. Zuul Filter Add more meaning to requests
37. Zuul Filter Why? • Helps to perform checks and filters
38. Distributed tracing Solution • Add a unique ID to each request • Record it in logs to trace the request • Record information like start and end time , use a tool to visualize your traces
39. Sleuth Yes ,I have been following him .
40. Sleuth The detective • As the name suggest , it silently adds tracing ID. • Each microservice prints this trace id
41. Sleuth in action • Just add sleuth to pom. • To visualize using Zipkin UI ,add cloud stream and rabbit MQ
42. Sleuth & Zipkins in action UI for all traces
43. Zipkin Let’s find out Download Zipkins
44. Hystrix No breaking pieces
45. Hystrix Fallback Mechanism • Provides better fault tolerance • Helps to rescue in case of failures
46. Spring Cloud Bus and Config server Freedom to Config changes deployments
47. Spring Cloud Bus and Config server Update Configs on the Go • Helps to update config • You can manage configs and no need to restart
48. Steps to Update 1. Add actuator to dependency 2. @RefreshScope of Bean 3. Allow actuator endpoints a. management.endpoints.web.exposure.include=* b. management.security.enabled=false 4. Use git to update files 5. Use actuator/refresh endpoints
49. Event Driven Microservices More Robust and Aysnc Processing
50. Benefits of Event Driven Microservices Love Async • Helps to build more robust microservices • Helps at achieving eventual consistency • Helps to decouple the microservices
51. Installing Kafka The Superheroic Event Framework
52. Steps to Install (Generic) 1. Download the Kafka a. http://mirrors.estointernet.in/apache/kafka/2.4.0/kafka_2.11-2.4.0.tgz b. Unzip the tar i. tar xzf kafka_2.11-2.4.0.tgz 2. Run Zookeeper a. bin/zookeeper-server-start.sh config/zookeeper.properties 3. Run Kafka a. bin/kafka-server-start.sh config/server.properties
53. Kafka send and Receive message On your commands ,GET ,SET >>GO
54. Send & Receive Messages 1. Create a topic a. bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication- factor 1 --partitions 1 --topic kafka-test-topic 2. Verify if Topic Got Created a. bin/kafka-topics.sh –list –zookeeper localhost:2181 3. Send Messages a. bin/kafka-console-producer.sh --broker-list localhost:9092 --topic kafka-test-topic >Welcome to Kafka 4. Receive Messages a. bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 -- topic kafka-test-topic --from-beginning
55. Adding Dependencies to Spring Project
56. Adding dependencies to Spring Project <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> </dependency> <dependency> <groupId>org.apache.kafka</groupId> <artifactId>kafka-streams</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-stream-binder-kafka</artifactId> </dependency> <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka-test</artifactId> <scope>test</scope> </dependency>
57. Kafka Producer
58. Configuring application properties spring: stream: default-binder: rabbit kafka: client-id : user-service bootstrap-servers: - localhost:9092 template: default-topic: tasks
59. Creating Required Beans @EnableKafka public class TaskConfig { @Autowired private KafkaProperties kafkaProperties; @Bean public Map<String, Object> producerConfigs() { Map<String, Object> props = new HashMap<>(); props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaProperties.getBootstrapServers()); props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class); props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class); return props; } @Bean public ProducerFactory<String, String> producerFactory() { return new DefaultKafkaProducerFactory<>(producerConfigs()); } @Bean public KafkaTemplate<String, String> kafkaTemplate() { return new KafkaTemplate<>(producerFactory()); } }
60. Send messages @PostMapping("send") public ResponseEntity<?> send(@RequestParam ("message") String message){ kafkaTemplate.send("tasks",message); return new ResponseEntity<>(HttpStatus.OK); }
61. Kafka Consumer
62. Configuring application properties spring: name: user-service cloud: stream: default-binder: rabbit kafka: listener: missing-topics-fatal: false client-id : user-service bootstrap-servers: - localhost:9092 template: default-topic: tasks
63. Creating Required Java Config @EnableKafka public class UserConfig { @Autowired private KafkaProperties kafkaProperties; @Bean public ConsumerFactory<String, String> consumerFactory() { Map<String, Object> props = new HashMap<>(); props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaProperties.getBootstrapServers()); props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,StringDeserializer.class); props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,StringDeserializer.class); return new DefaultKafkaConsumerFactory<>(props); } @Bean public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() { ConcurrentKafkaListenerContainerFactory<String, String> factory =new ConcurrentKafkaListenerContainerFactory<>(); factory.setConsumerFactory(consumerFactory()); return factory; } }
64. Recieve messages @KafkaListener(id = "tasks", topics = "tasks", containerFactory = "kafkaListenerContainerFactory") public void consume(@Payload String payload, @Header(KafkaHeaders.RECEIVED_PARTITION_ID) int partition, @Header(KafkaHeaders.RECEIVED_TOPIC) String incomingTopic, @Header(KafkaHeaders.RECEIVED_TIMESTAMP) long ts ) { LOGGER.info("Incoming message {}-> {}", incomingTopic, payload); }