Question 241837 in Redis Question posted in
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Lambda function running on localstack Testcontainers not able to connect to redis Testcontainers

I am writing integration tests for AWS lambda function that is invoked with KinesisEvent and then writes some data to Redis and Kafka.
I am using LocalStack and Testcontainers to achieve the same.

I have tested the code with docker-compose.yml, and it works fine. But something goes wrong in Java tests.

Here are my container settings –

@ClassRule
  public static final LocalStackContainer localstack =
      new LocalStackContainer(localstackImage)
          .withEnv("AWS_DEFAULT_REGION", US_EAST_1.getName())
              .withNetwork(lambdaNetwork)
          .withServices(Service.KINESIS, Service.LAMBDA);

  @ClassRule
  public static final KafkaContainer kafkaContainer =
      new KafkaContainer(kafkaImage).withNetwork(lambdaNetwork).withExposedPorts(9093);

    redisContainer = new GenericContainer<>(redisImage).withNetwork(lambdaNetwork).withExposedPorts(6379);
    redisContainer.start();

    String redisHost = redisContainer.getHost();
    Integer redisPort = redisContainer.getFirstMappedPort();

When I put record on kinesis, lambda is invoked successfully, however I get following exception –

2023-08-24T18:41:03.309  WARN --- [   asgi_gw_1] l.s.a.i.executor_endpoint  : Execution environment startup failed: {"errorMessage":"Failed to connect to any host resolved for DNS name.","errorType":"redis.clients.jedis.exceptions.JedisConnectionException"}

I am also setting up network for containers. Can someone point out what could I be missing?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Thanks to Eddu! His piece along with port mappings helped.

        List<String> portBindings = new ArrayList<>(); portBindings.add("6379:6379"); // hostPort:containerPort 
redisContainer =
        new GenericContainer<>(redisImage)
            .withNetwork(lambdaNetwork)
            .withNetworkMode(lambdaNetwork.getId())
            .withCreateContainerCmdModifier(
                new Consumer<CreateContainerCmd>() {
                  @Override
                  public void accept(CreateContainerCmd createContainerCmd) {
                    createContainerCmd.withHostName("cache");
                    createContainerCmd.withName("cache");
                  }
                })
            .withExtraHost("host.docker.internal", "host-gateway")
            .withCommand("redis-server", "--save", "20", "1", "--loglevel", "warning")
            .withNetworkAliases("cache")
            .withExposedPorts(6379); redisContainer.setPortBindings(portBindings); redisContainer.start();

  2. 0

    Having the following definition will allow to have the three containers use the same network

    • Postgres container
    • LocalStack container
    • Lambda container created by LocalStack
    static Network network = Network.newNetwork();

    @Container
    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:15-alpine")
            .withNetwork(network)
            .withNetworkAliases("postgres");

    @Container
    static LocalStackContainer localstack = new LocalStackContainer(DockerImageName.parse("localstack/localstack:2.2.0"))
            .withNetwork(network)
            .withEnv("LAMBDA_DOCKER_NETWORK", ((Network.NetworkImpl)network).getName())
            .withNetworkAliases("localstack");

    the key part is .withEnv("LAMBDA_DOCKER_NETWORK", ((Network.NetworkImpl)network).getName()) in LocalStackContainer

    Take into account to use the following information to connect from the lambda to postgres (in this example)

    url=jdbc:postgresql://postgres:5432/test
username=test
password=test

    Network alias postgres was declared in PostgresContainer, so it should be used by the lambda in order to connect through the docker network.

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