NATS¶

Since testcontainers-go v0.24.0

Introduction¶

The Testcontainers module for NATS.

Adding this module to your project dependencies¶

Please run the following command to add the NATS module to your Go dependencies:

go get github.com/testcontainers/testcontainers-go/modules/nats

Usage example¶

Creating a NATS container

ctx := context.Background()

natsContainer, err := nats.RunContainer(ctx,
    testcontainers.WithImage("nats:2.9"),
)
if err != nil {
    panic(err)
}

// Clean up the container
defer func() {
    if err := natsContainer.Terminate(ctx); err != nil {
        panic(err)
    }
}()

Module reference¶

The NATS module exposes one entrypoint function to create the NATS container, and this function receives two parameters:

func RunContainer(ctx context.Context, opts ...testcontainers.ContainerCustomizer) (*NATSContainer, error)

context.Context, the Go context.
testcontainers.ContainerCustomizer, a variadic argument for passing options.

Container Options¶

When starting the NATS container, you can pass options in a variadic way to configure it.

Image¶

If you need to set a different NATS Docker image, you can use testcontainers.WithImage with a valid Docker image for NATS. E.g. testcontainers.WithImage("nats:2.9").

Wait Strategies¶

If you need to set a different wait strategy for the container, you can use testcontainers.WithWaitStrategy with a valid wait strategy.

Info

The default deadline for the wait strategy is 60 seconds.

At the same time, it's possible to set a wait strategy and a custom deadline with testcontainers.WithWaitStrategyAndDeadline.

Startup Commands¶

Not available until the next release of testcontainers-go main

Testcontainers exposes the WithStartupCommand(e ...Executable) option to run arbitrary commands in the container right after it's started.

Info

To better understand how this feature works, please read the Create containers: Lifecycle Hooks documentation.

It also exports an Executable interface, defining one single method: AsCommand(), which returns a slice of strings to represent the command and positional arguments to be executed in the container.

You could use this feature to run a custom script, or to run a command that is not supported by the module right after the container is started.

Docker type modifiers¶

If you need an advanced configuration for the container, you can leverage the following Docker type modifiers:

testcontainers.WithConfigModifier
testcontainers.WithHostConfigModifier
testcontainers.WithEndpointSettingsModifier

Please read the Create containers: Advanced Settings documentation for more information.

Set username and password¶

If you need to set different credentials, you can use WithUsername and WithPassword options. By default, the username, the password are not set. To establish the connection with the NATS container:

Connect using the credentials

ctx := context.Background()

container, err := nats.RunContainer(ctx, nats.WithUsername("foo"), nats.WithPassword("bar"))
if err != nil {
    panic(err)
}

// Clean up the container
defer func() {
    if err := container.Terminate(ctx); err != nil {
        panic(err)
    }
}()

uri, err := container.ConnectionString(ctx)
if err != nil {
    panic(err)
}

nc, err := natsgo.Connect(uri, natsgo.UserInfo(container.User, container.Password))
if err != nil {
    panic(err)
}
defer nc.Close()

Container Methods¶

The NATS container exposes the following methods:

ConnectionString¶

This method returns the connection string to connect to the NATS container, using the default 4222 port. It's possible to pass extra parameters to the connection string, in a variadic way.

Get connection string

uri, err := container.ConnectionString(ctx)