Toxiproxy¶

Not available until the next release of testcontainers-go main

Introduction¶

The Testcontainers module for Toxiproxy.

Adding this module to your project dependencies¶

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

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

Usage example¶

Creating a Toxiproxy container

ctx := context.Background()

toxiproxyContainer, err := tctoxiproxy.Run(
    ctx,
    "ghcr.io/shopify/toxiproxy:2.12.0",
)
defer func() {
    if err := testcontainers.TerminateContainer(toxiproxyContainer); err != nil {
        log.Printf("failed to terminate container: %s", err)
    }
}()
if err != nil {
    log.Printf("failed to start container: %s", err)
    return
}

Module Reference¶

Run function¶

Not available until the next release of testcontainers-go main

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

func Run(ctx context.Context, img string, opts ...testcontainers.ContainerCustomizer) (*Container, error)

context.Context, the Go context.
string, the Docker image to use.
testcontainers.ContainerCustomizer, a variadic argument for passing options.

Container Ports¶

The Toxiproxy container exposes the following ports:

8474/tcp, the Toxiproxy control port, exported as toxiproxy.ControlPort.

Container Options¶

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

Image¶

Use the second argument in the Run function to set a valid Docker image. In example: Run(context.Background(), "shopify/toxiproxy:2.12.0").

Image Substitutions¶

Since testcontainers-go v0.26.0

In more locked down / secured environments, it can be problematic to pull images from Docker Hub and run them without additional precautions.

An image name substitutor converts a Docker image name, as may be specified in code, to an alternative name. This is intended to provide a way to override image names, for example to enforce pulling of images from a private registry.

Testcontainers for Go exposes an interface to perform this operation: ImageSubstitutor, and a No-operation implementation to be used as reference for custom implementations:

Image Substitutor InterfaceNoop Image Substitutor

// ImageSubstitutor represents a way to substitute container image names
type ImageSubstitutor interface {
    // Description returns the name of the type and a short description of how it modifies the image.
    // Useful to be printed in logs
    Description() string
    Substitute(image string) (string, error)
}

type NoopImageSubstitutor struct{}

// Description returns a description of what is expected from this Substitutor,
// which is used in logs.
func (s NoopImageSubstitutor) Description() string {
    return "NoopImageSubstitutor (noop)"
}

// Substitute returns the original image, without any change
func (s NoopImageSubstitutor) Substitute(image string) (string, error) {
    return image, nil
}

Using the WithImageSubstitutors options, you could define your own substitutions to the container images. E.g. adding a prefix to the images so that they can be pulled from a Docker registry other than Docker Hub. This is the usual mechanism for using Docker image proxies, caches, etc.

WithEnv¶

Since testcontainers-go v0.29.0

If you need to either pass additional environment variables to a container or override them, you can use testcontainers.WithEnv for example:

ctr, err = mymodule.Run(ctx, "docker.io/myservice:1.2.3", testcontainers.WithEnv(map[string]string{"FOO": "BAR"}))

WithExposedPorts¶

Not available until the next release of testcontainers-go main

If you need to expose additional ports from the container, you can use testcontainers.WithExposedPorts. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithExposedPorts("8080/tcp", "9090/tcp"))

WithEntrypoint¶

Not available until the next release of testcontainers-go main

If you need to completely replace the container's entrypoint, you can use testcontainers.WithEntrypoint. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithEntrypoint("/bin/sh", "-c", "echo hello"))

WithEntrypointArgs¶

Not available until the next release of testcontainers-go main

If you need to append commands to the container's entrypoint, you can use testcontainers.WithEntrypointArgs. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithEntrypointArgs("echo", "hello"))

WithCmd¶

Not available until the next release of testcontainers-go main

If you need to completely replace the container's command, you can use testcontainers.WithCmd. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithCmd("echo", "hello"))

WithCmdArgs¶

Not available until the next release of testcontainers-go main

If you need to append commands to the container's command, you can use testcontainers.WithCmdArgs. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithCmdArgs("echo", "hello"))

WithLabels¶

Not available until the next release of testcontainers-go main

If you need to add Docker labels to the container, you can use testcontainers.WithLabels. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithLabels(map[string]string{
        "environment": "testing",
        "project":     "myapp",
    }))

WithFiles¶

Not available until the next release of testcontainers-go main

If you need to copy files into the container, you can use testcontainers.WithFiles. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithFiles([]testcontainers.ContainerFile{
        {
            HostFilePath:      "/path/to/local/file.txt",
            ContainerFilePath: "/container/file.txt",
            FileMode:          0o644,
        },
    }))

This option allows you to copy files from the host into the container at creation time.

WithMounts¶

Not available until the next release of testcontainers-go main

If you need to add volume mounts to the container, you can use testcontainers.WithMounts. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithMounts([]testcontainers.ContainerMount{
        {
            Source: testcontainers.GenericVolumeMountSource{Name: "appdata"},
            Target: "/app/data",
        },
    }))

WithTmpfs¶

Not available until the next release of testcontainers-go main

If you need to add tmpfs mounts to the container, you can use testcontainers.WithTmpfs. For example:

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithTmpfs(map[string]string{
        "/tmp": "size=100m",
        "/run": "size=100m",
    }))

WithHostPortAccess¶

Since testcontainers-go v0.31.0

If you need to access a port that is already running in the host, you can use testcontainers.WithHostPortAccess for example:

ctr, err = mymodule.Run(ctx, "docker.io/myservice:1.2.3", testcontainers.WithHostPortAccess(8080))

To understand more about this feature, please read the Exposing host ports to the container documentation.

WithLogConsumers¶

Since testcontainers-go v0.28.0

If you need to consume the logs of the container, you can use testcontainers.WithLogConsumers with a valid log consumer. An example of a log consumer is the following:

type TestLogConsumer struct {
    Msgs []string
}

func (g *TestLogConsumer) Accept(l Log) {
    g.Msgs = append(g.Msgs, string(l.Content))
}

WithLogger¶

Since testcontainers-go v0.29.0

If you need to either pass logger to a container, you can use testcontainers.WithLogger.

Info

Consider calling this before other "With" functions as these may generate logs.

In this example we also use the testcontainers-go log.TestLogger, which writes to the passed in testing.TB using Logf. The result is that we capture all logging from the container into the test context meaning its hidden behind go test -v and is associated with the relevant test, providing the user with useful context instead of appearing out of band.

func TestHandler(t *testing.T) {
    logger := log.TestLogger(t)
    ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", testcontainers.WithLogger(logger))
    CleanupContainer(t, ctr)
    require.NoError(t, err)
    // Do something with container.
}

Please read the Following Container Logs documentation for more information about creating log consumers.

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¶

Since testcontainers-go v0.25.0

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 the following methods:

AsCommand(), which returns a slice of strings to represent the command and positional arguments to be executed in the container;
Options(), which returns the slice of functional options with the Docker's ExecConfigs used to create the command in the container (the working directory, environment variables, user executing the command, etc) and the possible output format (Multiplexed).

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.

Ready Commands¶

Since testcontainers-go v0.28.0

Testcontainers exposes the WithAfterReadyCommand(e ...Executable) option to run arbitrary commands in the container right after it's ready, which happens when the defined wait strategies have finished with success.

Info

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

It leverages the Executable interface 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 ready.

Build from Dockerfile¶

Not available until the next release of testcontainers-go main

Testcontainers exposes the testcontainers.WithDockerfile option to build a container from a Dockerfile. The functional option receives a testcontainers.FromDockerfile struct that is applied to the container request before starting the container. As a result, the container is built and started in one go.

df := testcontainers.FromDockerfile{
    Context:    ".",
    Dockerfile: "Dockerfile",
    Repo:       "testcontainers",
    Tag:        "latest",
    BuildArgs:  map[string]*string{"ARG1": nil, "ARG2": nil},
}   

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", testcontainers.WithDockerfile(df))

WithNetwork¶

Since testcontainers-go v0.27.0

By default, the container is started in the default Docker network. If you want to use an already existing Docker network you created in your code, you can use the network.WithNetwork(aliases []string, nw *testcontainers.DockerNetwork) option, which receives an alias as parameter and your network, attaching the container to it, and setting the network alias for that network.

In the case you need to retrieve the network name, you can simply read it from the struct's Name field. E.g. nw.Name.

Warning

This option is not checking whether the network exists or not. If you use a network that doesn't exist, the container will start in the default Docker network, as in the default behavior.

WithNewNetwork¶

Since testcontainers-go v0.27.0

If you want to attach your containers to a throw-away network, you can use the network.WithNewNetwork(ctx context.Context, aliases []string, opts ...network.NetworkCustomizer) option, which receives an alias as parameter, creating the new network with a random name, attaching the container to it, and setting the network alias for that network.

In the case you need to retrieve the network name, you can use the Networks(ctx) method of the Container interface, right after it's running, which returns a slice of strings with the names of the networks where the container is attached.

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.

Customising the ContainerRequest¶

This option will merge the customized request into the module's own ContainerRequest.

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3",
    /* Other module options */
    testcontainers.CustomizeRequest(testcontainers.GenericContainerRequest{
        ContainerRequest: testcontainers.ContainerRequest{
            Cmd: []string{"-c", "log_statement=all"},
        },
    }),
)

The above example is updating the predefined command of the image, appending them to the module's command.

Info

This can't be used to replace the command, only to append options.

WithReuseByName¶

Not available until the next release of testcontainers-go main

This option marks a container to be reused if it exists or create a new one if it doesn't. With the current implementation, the container name must be provided to identify the container to be reused.

ctr, err := mymodule.Run(ctx, "docker.io/myservice:1.2.3", 
    testcontainers.WithReuseByName("my-container-name"),
)

Warning

Reusing a container is experimental and the API is subject to change for a more robust implementation that is not based on container names.

WithProxy¶

Not available until the next release of testcontainers-go main

The WithProxy option allows you to specify a proxy to be created on the Toxiproxy container. This option allocates a random port on the host and exposes it to the Toxiproxy container, allowing you to create a unique proxy for a given service, starting from the 8666/tcp port.

func WithProxy(name string, upstream string) Option

If this option is used in combination with the WithConfigFile option, the proxy defined in this option is added to the proxies defined in the config file.

Info

If you add proxies in a programmatic manner using the Toxiproxy client, then you need to manually add exposed ports in the Toxiproxy container.

WithConfigFile¶

Not available until the next release of testcontainers-go main

The WithConfigFile option allows you to specify a config file for the Toxiproxy container, in the form of an io.Reader representing the JSON file with the Toxiproxy configuration, in the valid format of the Toxiproxy configuration file.

Configuration file

[
    {
        "name": "redis",
        "listen": "0.0.0.0:8666",
        "upstream": "redis:6379",
        "enabled": true
    }
]

func WithConfigFile(r io.Reader) testcontainers.CustomizeRequestOption

If this option is used in combination with the WithProxy option, the proxies defined in this option are added to the proxies defined with the WithProxy option.

Container Methods¶

The Toxiproxy container exposes the following methods:

ProxiedEndpoint¶

Not available until the next release of testcontainers-go main

The ProxiedEndpoint method returns the host and port of the proxy for a given port. It's used to create new connections to the proxied service, and it returns an error in case the port has no proxy.

func (c *Container) ProxiedEndpoint(port int) (string, string, error)

Get Proxied EndpointRead Proxied Endpoint

proxiedRedisHost, proxiedRedisPort, err := toxiproxyContainer.ProxiedEndpoint(8666)
if err != nil {
    log.Printf("failed to get toxiproxy container port: %s", err)
    return
}

// Create a redis client that connects to the toxiproxy container.
// We are defining a read timeout of 2 seconds, because we are adding
// a latency toxic of 1.1 seconds to the request.
redisURI := fmt.Sprintf("redis://%s:%s?read_timeout=2s", proxiedRedisHost, proxiedRedisPort)

The above examples show how to get the proxied endpoint and use it to create a new connection to the proxied service, in this case a Redis client.

URI¶

Not available until the next release of testcontainers-go main

The URI method returns the URI of the Toxiproxy container, used to create a new Toxiproxy client.

func (c *Container) URI() string

Creating a Toxiproxy client

toxiURI, err := toxiproxyContainer.URI(ctx)
if err != nil {
    log.Printf("failed to get toxiproxy container uri: %s", err)
    return
}

toxiproxyClient := toxiproxy.NewClient(toxiURI)

the toxiproxy package comes from the github.com/Shopify/toxiproxy/v2/client package.
the toxiproxyContainer variable has been created by the Run function.

Examples¶

Programmatically create a proxy¶

Expose port manuallyCreating a proxyCreating a Redis clientAdding a latency toxic

const proxyPort = "8666"

// No need to create a proxy, as we are programmatically adding it below.
toxiproxyContainer, err := tctoxiproxy.Run(
    ctx,
    "ghcr.io/shopify/toxiproxy:2.12.0",
    network.WithNetwork([]string{"toxiproxy"}, nw),
    // explicitly expose the ports that will be proxied using the programmatic API
    // of the toxiproxy client. Otherwise, the ports will not be exposed and the
    // toxiproxy client will not be able to connect to the proxy.
    testcontainers.WithExposedPorts(proxyPort+"/tcp"),
)
defer func() {
    if err := testcontainers.TerminateContainer(toxiproxyContainer); err != nil {
        log.Printf("failed to terminate container: %s", err)
    }
}()
if err != nil {
    log.Printf("failed to start container: %s", err)
    return
}

// Create the proxy using the network alias of the redis container,
// as they run on the same network.
proxy, err := toxiproxyClient.CreateProxy("redis", "0.0.0.0:"+proxyPort, "redis:6379")
if err != nil {
    log.Printf("failed to create proxy: %s", err)
    return
}

// Create a redis client that connects to the toxiproxy container.
// We are defining a read timeout of 2 seconds, because we are adding
// a latency toxic of 1 second to the request, +/- 100ms jitter.
redisURI := fmt.Sprintf("redis://%s:%s?read_timeout=2s", toxiproxyProxyHostIP, toxiproxyProxyPort.Port())

options, err := redis.ParseURL(redisURI)
if err != nil {
    log.Printf("failed to parse url: %s", err)
    return
}

redisCli := redis.NewClient(options)
defer func() {
    if err := redisCli.FlushAll(ctx).Err(); err != nil {
        log.Printf("failed to flush redis: %s", err)
    }
}()

const (
    latency = 1_000
    jitter  = 200
)
// Add a latency toxic to the proxy
_, err = proxy.AddToxic("latency_down", "latency", "downstream", 1.0, toxiproxy.Attributes{
    "latency": latency,
    "jitter":  jitter,
})
if err != nil {
    log.Printf("failed to add toxic: %s", err)
    return
}