.NET Core service can't access dynamodb-local when both are ran from docker-compose-CodePudding

I am building a rest service in .NET Core 6 in Visual Studio 2022. This service is using dynamodb for its database. I am running both of these inside Docker with a single docker-compose file.

If I startup dynamodb-local in it's own docker-compose file like this

version: '3.4'

services:

  dynamodb-local:
    image: amazon/dynamodb-local:latest
    container_name: dynamodb-local    
    command: "-jar DynamoDBLocal.jar -sharedDb"
    ports:
      - "8000:8000"

I configure the client in the Program.cs like this

var clientConfig = new AmazonDynamoDBConfig {ServiceURL = "http://localhost:8000" };
builder.Services.AddSingleton<IAmazonDynamoDB>(_ => new AmazonDynamoDBClient(clientConfig));

If I run the service from IIS Express, everything works perfectly.

However, I enabled containerization for the project and want to run everything together inside docker. When I do this my, my docker-compose looks like this:

version: '3.4'

services:

  dynamodb-local:
    image: amazon/dynamodb-local:latest    
    container_name: dynamodb-local    
    command: "-jar DynamoDBLocal.jar -sharedDb"
    ports:
      - "8000:8000"    
    
  api:
    image: ${DOCKER_REGISTRY-}api    
    container_name: insurance-service    
    build:
      context: .
      dockerfile: src/Api/Dockerfile        
    depends_on:
      - dynamodb-local

Then my docker-compose-override.yml looks like this (this was generated by VS):

version: '3.4'

services:
  api:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development
      - ASPNETCORE_URLS=https:// :443;http:// :80
    ports:
      - "80"
      - "443"
    volumes:
      - ${APPDATA}/Microsoft/UserSecrets:/root/.microsoft/usersecrets:ro
      - ${APPDATA}/ASP.NET/Https:/root/.aspnet/https:ro

When I start this up using docker-compose inside VS 2022, everything loads up fine. But when I go to save a record to the database this error is thrown:

Amazon.Runtime.AmazonServiceException: Unable to get IAM security credentials from EC2 Instance Metadata Service.

It's like the client registering is trying to access localhost:8000 but there seems to be nothing there so it defaults back to EC2 IAM Security Creds. I think this is being caused by some weird networking between the 2 services that I don't realize. Like API can't access dynamodb-local with referencing localhost.

Edit: I have also tried throwing arbitrary basic creds in there like this:

var clientConfig = new AmazonDynamoDBConfig { ServiceURL = "http://localhost:8000" };
var creds = new BasicAWSCredentials("xxx", "xxx");
builder.Services.AddSingleton<IAmazonDynamoDB>(_ => new AmazonDynamoDBClient(creds, clientConfig));

This doesn't give me the IAM issue but keeps trying in an infinite loop like it's waiting for localhost to become available and it isn't.

CodePudding user response：

Why don't you try using networking between containers? You can create a network and then access the DynamoDB using the container name, this way the DynamoDB container is accessible internally.

version: '3.4'

services:

  dynamodb-local:
    image: amazon/dynamodb-local:latest    
    container_name: dynamodb-local    
    command: "-jar DynamoDBLocal.jar -sharedDb"
    ports:
      - "8000:8000"    
    
  api:
    image: ${DOCKER_REGISTRY-}api    
    container_name: insurance-service    
    build:
      context: .
      dockerfile: src/Api/Dockerfile        
    depends_on:
      - dynamodb-local
networks:
  default:
    external:
      name: dynamodb-api

And your can replace the URL with the container name like this:

var clientConfig = new AmazonDynamoDBConfig { ServiceURL = "dynamodb-local" };
var creds = new BasicAWSCredentials("xxx", "xxx");
builder.Services.AddSingleton<IAmazonDynamoDB>(_ => new AmazonDynamoDBClient(creds, clientConfig));

You will also have to create a docker network with this command

docker network create dynamodb-api

Hope this helps!