[Feature]: improve developer experience with azure/eventhubs

[thecoldwine]

Problem

Currently, there is no feature parity between options provided by golang azure/eventhubs and C# azure/eventhubs modules and I personally do find dev experience in go a bit lacking. Example:

void Setup()
{
    var network = new NetworkBuilder().Build();
    
    AzuriteInstance = new AzuriteBuilder("mcr.microsoft.com/azure-storage/azurite:3.34.0")
        .WithNetwork(network)
        .WithNetworkAliases("azurite")
        .Build();

    EventHubsInstance = new EventHubsBuilder("mcr.microsoft.com/azure-messaging/eventhubs-emulator:latest")
        .WithAcceptLicenseAgreement(true)
        .WithAzuriteContainer(network, AzuriteInstance, "azurite")
        .WithConfigurationBuilder(
            EventHubsServiceConfiguration.Create()
                .WithEntity(EventHubEntityName, 2, "$Default"))
        .WithWaitStrategy(Wait.ForUnixContainer()
            .UntilMessageIsLogged("Emulator Service is Successfully Up!"))
        .Build();
}

Solution

In go we're missing a couple of things here:

1. Statically typed configurations (fluent api or building a structure with merge as an alternative to plain reader configuration).
2. Way to provide Azurite container itself, not just an image (in case I would like to reset checkpoints within image and to have 1 less container to spin up).

As far as I see all necessary infrastructure is already in place in https://github.com/testcontainers/testcontainers-go/blob/main/modules/azure/eventhubs/options.go

It is especially useful if one needs azurite with non-standard options, i.e.: testcontainers.WithEntrypointArgs("--skipApiVersionCheck")

So, it would be nice to have something in line with:

func WithAzuriteContainer(
    azuriteContainer *azurite.Container, 
    network          *testcontainers.DockerNetwork,
    opts ...testcontainers.ContainerCustomizer,
) Option {
	return func(o *options) error {
    	o.azuriteOptions = opts
    	o.azuriteContainer = azuriteContainer
    	o.network = network
    }
}

For statically typed configuration it is a bit trickier, but it would be nice to just supply a struct which is afterwards marshalled as JSON and then put into the configuration, so:

cfg := NewConfigBuilder().
	WithLoggingType("File").
	AddNamespace("emulatorNs1", "EventHub").
		AddEntity("eh1", "2").
			AddConsumerGroup("cg1").
			Done(). // back to NamespaceBuilder
		Done(). // back to ConfigBuilder
	Build()

and then supply it to options via:

func WithConfigObject(cfg *eventhubConfig) testcontainers.CustomizeRequestOption {
	return func(req *testcontainers.GenericContainerRequest) error {
                 // marshal JSON to configuration path here

		req.Files = append(req.Files, testcontainers.ContainerFile{
			Reader:            r,
			ContainerFilePath: containerConfigFile,
			FileMode:          0o644,
		})

		return nil
	}
}

Benefit

It makes dev ux a bit less frustrating and more consistent to what is already there in testcontainers for other languages

Alternatives

Generate helper functions in every codebase or publish as a separate library, but it is much more incovenient. Another option is do templating:

const ConfigTemplate = `
{
  "UserConfig": {
    "NamespaceConfig": [
      {
        "Type": "EventHub",
        "Name": "%s",
        "Entities": [
          {
            "Name": "%s",
            "PartitionCount": "%d",
            "ConsumerGroups": [{ "Name": "%s" }]
          }
        ]
      }
    ],
    "LoggingConfig": { "Type": "File" }
  }
}
`
const EventHubNamespace = "ehNamespace"
const EventHubName = "eh1"
const PartitionCount = 2
const ConsumerGroup = "default"

func renderConfiguration() io.Reader {
	renderedConfig := fmt.Sprintf(
		ConfigTemplate,
		EventHubNamespace,
		EventHubName,
		PartitionCount,
		ConsumerGroup,
	)

	return strings.NewReader(renderedConfig)
}

// then use it like this:
...

	eventhubsContainer, err := eventhubs.Run(
		context.Background(),
		"mcr.microsoft.com/azure-messaging/eventhubs-emulator:latest",
		eventhubs.WithAcceptEULA(),
		eventhubs.WithAzurite("mcr.microsoft.com/azure-storage/azurite:3.34.0"),
		eventhubs.WithConfig(renderConfiguration()),
	)
...

Would you like to help contributing this feature?

Yes