DEV Community: Mac

Publish a message from an SNS in one AWS account to an SQS in a different AWS account

Mac — Sat, 29 Jul 2023 07:02:38 +0000

Suppose you have AWS SNS in Account A and you want to publish a message to AWS SQS in Account B. Here's how you can do it.

Account A :

Create a new standard SNS topic and add the following policy to allow an SQS from another account to subscribe

{
   "Effect":"Allow",
   "Principal":{
      "AWS":"<ID_OF_ACCOUNT_B>"
   },
   "Action":"sns:Subscribe",
   "Resource":"arn:aws:sns:<REGION>:<ID_OF_ACCOUNT_A>:<TOPIC_NAME>"
}

Account B :

Create a new IAM user with permission to read message to SQS. Also create access key for IAM user. access key will be used by consumer for reading message from SQS.
Create a new KMS and allow IAM user to encrypt and decrypt message by choosing IAM user from 1.
Add the following policy to KMS from 2. to allow SNS from account A to be able to send encrypt message to SQS

        {
            "Sid": "Allow use of the key from another account",
            "Effect": "Allow",
            "Principal": {
                "Service": "sns.amazonaws.com",
                "AWS": "arn:aws:iam::{ACCOUNT_OF_SNS}:root"
            },
            "Action": "kms:*",
            "Resource": "*"
        }

Create a new SQS with SSE KMS

References :

https://www.youtube.com/watch?v=Von_VgswnJU

API Gateway and Lambda

Mac — Sat, 02 May 2020 16:45:24 +0000

Below is an example of how to create API Gateway that trigger Lambda by using 3 difference Infrastructure as Code tools.

AWS CloudFormation

Example, https://github.com/MacKittipat/mac-cloudformation-helloworld/blob/master/cloudformation.yaml

AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  LambdaFunctionName:
    Type: String
    Default: HelloWorld
Resources:
  # API Gateway
  ApiGatewayRestApiHelloWorld:
    Type: 'AWS::ApiGateway::RestApi'
    Properties:
      Name: HelloWorldApi
  ApiGatewayResourceHelloWorld:
    Type: 'AWS::ApiGateway::Resource'
    Properties:
      RestApiId: !Ref ApiGatewayRestApiHelloWorld
      ParentId: !GetAtt ApiGatewayRestApiHelloWorld.RootResourceId
      PathPart: !Ref LambdaFunctionName
  ApiGatewayMethodHelloWorld:
    Type: 'AWS::ApiGateway::Method'
    Properties:
      HttpMethod: ANY
      ResourceId: !Ref ApiGatewayResourceHelloWorld
      RestApiId: !Ref ApiGatewayRestApiHelloWorld
      ApiKeyRequired: false
      AuthorizationType: NONE
      MethodResponses:
        - StatusCode: '200'
      Integration:
        ConnectionType: INTERNET
        IntegrationHttpMethod: POST
        Type: AWS_PROXY
        Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${LambdaFunctionHelloWorld.Arn}/invocations'
  ApiGatewayDeploymentHelloWorld:
    DependsOn: ApiGatewayMethodHelloWorld
    Type: 'AWS::ApiGateway::Deployment'
    Properties:
      RestApiId: !Ref ApiGatewayRestApiHelloWorld
      StageName: prod
  # Lambda Function
  LambdaFunctionHelloWorld:
    Type: 'AWS::Lambda::Function'
    Properties:
      FunctionName: !Ref LambdaFunctionName
      Code:
        ZipFile: |
          exports.handler = async function(event) {
            const response = {
              statusCode: 200,
              body: "Hello World. Build with CloudFormation",
            };
            return response;
          }
      Handler: index.handler
      Role: {ROLE}
      Runtime: nodejs12.x
  LambdaPermissionHelloWorld:
    Type: 'AWS::Lambda::Permission'
    Properties:
      FunctionName: !GetAtt LambdaFunctionHelloWorld.Arn
      Action: lambda:InvokeFunction
      Principal: apigateway.amazonaws.com
      SourceArn: !Sub 'arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${ApiGatewayRestApiHelloWorld}/*/*/${LambdaFunctionName}'

Serverless Framework

Example, https://github.com/MacKittipat/mac-serverless-helloearth

provider:
  name: aws
  runtime: nodejs12.x
  stage: dev
  region: ap-southeast-1
functions:
  hello:
    handler: handler.helloEarth
    events:
      - http:
          path: HelloEarth
          method: get

AWS CDK

Example, https://github.com/MacKittipat/mac-cdk-helloplanet

import * as cdk from '@aws-cdk/core';
import * as lambda from '@aws-cdk/aws-lambda';
import * as apiGateway from '@aws-cdk/aws-apigateway';

export class MacCdkHelloplanetStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const functionName = 'HelloPlanet';
    const lambdaFunction = new lambda.Function(this, functionName, {
      runtime: lambda.Runtime.NODEJS_12_X,
      handler: 'index.handler',
      code: lambda.Code.fromAsset('resources'),
    });

    const gatewayRestApi = new apiGateway.RestApi(this, functionName + 'Api', {
      restApiName: functionName + 'Api',
      deployOptions: {
        stageName: 'prod'
      }
    })

    const gatewayLambdaIntegration = new apiGateway.LambdaIntegration(lambdaFunction, {
      allowTestInvoke: false
    });

    const gatewayResource = gatewayRestApi.root.addResource(functionName);
    gatewayResource.addMethod("GET", gatewayLambdaIntegration)

  }
}

Spring Boot : Handling Exception

Mac — Mon, 27 Apr 2020 15:39:57 +0000

Example of how to handling exception in Spring Boot.

Annotate Exception with @ResponseStatus

@ResponseStatus(code = HttpStatus.INTERNAL_SERVER_ERROR, reason = "I don't know...")
public class MyException extends Exception {

    public MyException(String message) {
        super(message);
    }
}

This will response HTML error page as screenshot below.

Throw ResponseStatusException from Controller.

@GetMapping("/users/{id}")
public User findUser(@PathVariable Long id) throws MyException {
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "I don't know this too...");
}

Use @ControllerAdvice as global exception handling.

@ExceptionHandler(MyException.class)
@ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
@ResponseBody
public String handleMyException(HttpServletRequest request, Throwable ex) {
    return "I don't know anything...";
}

We can remove @ResponseBody if we use @RestControllerAdvice instead of @ControllerAdvice

Spring Boot : Actuator

Mac — Sun, 26 Apr 2020 14:20:28 +0000

Use for monitor and manage running application.

Enable by adding dependency below.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

Using HTTP endpoint

/actuator/health
- Return status of running application
/actuator/info
- Usually return blank but we can customize it in application.properties.
- @project.version@ refer to version tag in pom.xml

info.app.version=@project.version@
info.app.name=Hello World

Using JMX

This option is disable by default but we can enable by set spring.jmx.enabled to true
Data will be exposed under org.springframework.boot domain.

Spring Boot : RestTemplate

Mac — Sat, 25 Apr 2020 06:11:14 +0000

Spring Boot does not provide auto-configured RestTemplate bean but we can create it by

1.) Initialize RestTemplate

@Bean
public RestTemplate restTemplate() {
    return new RestTemplate();
}

2.) Using RestTemplateBuilder

@Bean
public RestTemplate restTemplate(RestTemplateBuilder restTemplateBuilder) {
    return restTemplateBuilder.build();
}

CRUD Operation on RestTemplate

restTemplate.getForEntity();
restTemplate.postForEntity();
restTemplate.put();
restTemplate.delete();

Spring Boot : Unit Test

Mac — Wed, 22 Apr 2020 15:27:30 +0000

Example of how to write unit test in Spring Boot.

// UserController.java
@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/users/{id}")
    public User findUser(@PathVariable Long id) {
        return userService.findById(id);
    }
}

// UserService.java
@Service
public class UserService {

    @Autowired
    private UserRepo userRepo;

    public User findById(Long id) {
        return userRepo.findById(id);
    }
}


// UserRepo.java
@Service
public class UserRepo {

    public User findById(Long id) {
        return User.builder()
                .id(id)
                .name("Mac")
                .build();
    }
}

// User.java
@Data
@Builder
public class User {

    private Long id;
    private String name;

}

Test Service class

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserServiceTest {

    @InjectMocks
    private UserService userService;

    @Mock
    private UserRepo userRepo;

    @Test
    public void testFindById() {
        Mockito.when(userRepo.findById(Mockito.anyLong())).thenReturn(User.builder()
                .id(1L)
                .name("Mac")
                .build());

        User user = userService.findById(1L);

        Assert.assertEquals(1L, user.getId().longValue());
        Assert.assertEquals("Mac", user.getName());
        Mockito.verify(userRepo, Mockito.times(1)).findById(Mockito.any());
    }
}

Test Controller class

@RunWith(SpringRunner.class)
@WebMvcTest(UserController.class)
public class UserControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private UserService userService;

    @Autowired
    private ObjectMapper objectMapper;

    @Test
    public void testFindUser() throws Exception {

        User user = User.builder()
                .id(1L)
                .name("Mac")
                .build();
        Mockito.when(userService.findById(Mockito.any())).thenReturn(user);

        mockMvc.perform(MockMvcRequestBuilders.get("/users/1"))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andExpect(MockMvcResultMatchers.content()
                        .json(objectMapper.writeValueAsString(user)));
    }
}

Note

@RunWith(SpringRunner.class) is require if you use JUnit 4.
By default, @SpringBootTest will not start server but you can configure it with webEnvironment attribute.

Reference : https://stackoverflow.com/questions/44200720/difference-between-mock-mockbean-and-mockito-mock

Spring Boot : Spring Data JPA

Mac — Tue, 21 Apr 2020 15:03:36 +0000

Example of how to configure Spring Data JPA

pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
    <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.2.12</version>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.12</version>
    <scope>provided</scope>
</dependency>

application.properties

spring.datasource.url=jdbc:postgresql://localhost/{DBNAME}
spring.datasource.username={USERNAME}
spring.datasource.password={PASSWORD}
spring.datasource.driver-class-name=org.postgresql.Driver

Customer.java

@Data
@Entity
public class Customer {

    @Id
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long id;

    private String name;
}

CustomerRepository.java

public interface CustomerRepository extends CrudRepository<Customer, Long> {

    Optional<Customer> findById(Long id);
}

Spring Boot : JDBCTemplate

Mac — Tue, 21 Apr 2020 14:24:21 +0000

Example of how to setup Spring Boot with JDBCTeamplate

pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
    <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.2.12</version>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.12</version>
    <scope>provided</scope>
</dependency>

spring-boot-starter-jdbc and JDBC Driver, in this case postgresql is mandatory.

application.properties

spring.datasource.url=jdbc:postgresql://localhost/{DBNAME}
spring.datasource.username={USERNAME}
spring.datasource.password={PASSWORD}
spring.datasource.driver-class-name=org.postgresql.Driver

We often don't need spring.datasource.driver-class-name because Spring can figured it out from url.

App.java

@Slf4j
@SpringBootApplication
public class App implements CommandLineRunner {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    public static void main( String[] args ) {
        SpringApplication springApplication = new SpringApplication(App.class);
        springApplication.setWebApplicationType(WebApplicationType.NONE);
        springApplication.run(args);
    }

    @Override
    public void run(String... args) throws Exception {
        log.info("Count total row = {}", 
            jdbcTemplate.queryForObject("SELECT COUNT(id) FROM customer", Integer.class));
    }
}

JdbcTemplate is auto configured in Spring. We can Autowired it directly into any Spring bean class.

Spring Boot : Enable CORS

Mac — Mon, 20 Apr 2020 15:00:05 +0000

If you have client app running on http://localhost:4200 and it make a request to API written in Spring Boot that is running on http://localhost:8080, You should get the below error because client app and API has a different origin (domain, protocol or port).



Access to XMLHttpRequest at 'http://localhost:8080/hello' from origin 'http://localhost:4200' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

You can resolve this problem by enable CORS in Spring Boot.

At Class or Method level



@RestController
public class MainController {

    @CrossOrigin(origins = "http://localhost:4200")
    @GetMapping("/hello")
    public User hello() throws Exception {
        return User.builder().name("Mac").build();
    }
}

Global ```java

@Configuration
public class WebConfig {

@Bean
public WebMvcConfigurer corsConfigurer() {
    return new WebMvcConfigurer() {
        @Override
        public void addCorsMappings(CorsRegistry registry) {
            registry.addMapping("/**").allowedOrigins("http://localhost:4200");
        }
    };
}

}

Spring Boot : @Profile

Mac — Sun, 19 Apr 2020 14:32:51 +0000

// MessageReader.java
public interface MessageReader {
    String read();
}

// FileMessageReader.java
@Profile("default")
@Service
public class FileMessageReader implements MessageReader {

    @Override
    public String read() {
        return "Read from file";
    }
}

// DbMessageReader .java
@Profile("prod")
@Service
public class DbMessageReader implements MessageReader {

    @Override
    public String read() {
        return "Read from DB";
    }
}

// App.java
@Autowired
private MessageReader messageReader;

If profile prod is active, DbMessageReader should be injected into MessageReader.

Spring Boot : Get property value

Mac — Sun, 19 Apr 2020 14:20:07 +0000

If you have a properties, You can get the value by using @Value, Environment or @ConfigurationProperties

app.msg=Hello World
app.version=1.0.0

@Value

@Value("${app.msg}")
private String msg;

@Value("${app.version}")
private String version;

Environment

@Autowired
private Environment environment;

// ---

environment.getProperty("app.msg")
environment.getProperty("app.version")

@ConfigurationProperties

@Configuration
@ConfigurationProperties("app")
public class AppConfig {

    private String msg;
    private String version;

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }
}

// ---

@Autowired
private AppConfig appConfig;

Spring Boot : Properties file

Mac — Sun, 19 Apr 2020 08:40:24 +0000

Properties file

Default properties file is application.properties
Default profiles file is application-default.properties

If application have the following properties file

// application.properties
app.msg=Hello World
app.version=1.0.0

// application-default.properties
app.msg=Default

// application-prod.properties
app.msg=Prod

java -jar app.jar should get

app.msg=Default
app.version=1.0.0

java -jar -Dspring.profiles.active=prod app.jar should get

app.msg=Prod
app.version=1.0.0

Start Spring Boot with profile

// Java 
java -jar -Dspring.profiles.active=prod app.jar

// Maven
mvn spring-boot:run -Dspring-boot.run.profiles=prod

Windows PowerShell required double quote around parameter

java -jar "-Dspring.profiles.active=prod app.jar"
mvn spring-boot:run "-Dspring-boot.run.profiles=prod"