etcd¶
Not available until the next release of testcontainers-go main
Introduction¶
The Testcontainers module for etcd.
Adding this module to your project dependencies¶
Please run the following command to add the etcd module to your Go dependencies:
go get github.com/testcontainers/testcontainers-go/modules/etcd
Usage example¶
ctx := context.Background()
etcdContainer, err := etcd.Run(ctx, "gcr.io/etcd-development/etcd:v3.5.14")
defer func() {
if err := testcontainers.TerminateContainer(etcdContainer); 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 etcd module exposes one entrypoint function to create the etcd container, and this function receives three parameters:
func Run(ctx context.Context, img string, opts ...testcontainers.ContainerCustomizer) (*etcdContainer, error)
context.Context
, the Go context.string
, the Docker image to use.testcontainers.ContainerCustomizer
, a variadic argument for passing options.
Container Options¶
When starting the etcd container, you can pass options in a variadic way to configure it.
Image¶
If you need to set a different etcd Docker image, you can set a valid Docker image as the second argument in the Run
function.
E.g. Run(context.Background(), "bitnami/etcd:latest")
.
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 operations: ImageSubstitutor
, and a No-operation implementation to be used as reference for custom implementations:
// 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:
postgres, err = postgresModule.Run(ctx, "postgres:15-alpine", testcontainers.WithEnv(map[string]string{"POSTGRES_INITDB_ARGS": "--no-sync"}))
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:
postgres, err = postgresModule.Run(ctx, "postgres:15-alpine", 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 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 := TestLogger(t)
ctr, err := postgresModule.Run(ctx, "postgres:15-alpine", 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.
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
.
container, err := Run(ctx, "postgres:13-alpine",
/* 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.
WithAdditionalArgs¶
- Not available until the next release of testcontainers-go main
You can pass additional arguments to the etcd container by using the WithAdditionalArgs
option. The arguments are passed to the CMD of the etcd container.
WithDataDir¶
- Not available until the next release of testcontainers-go main
You can set the data directory for the etcd container by using the WithDataDir
boolean option. The data directory where the etcd data is stored is /data.etcd
.
WithNodes¶
- Not available until the next release of testcontainers-go main
You can set the number of nodes for the etcd cluster by using the WithNodes
option, passing the node names for each of the nodes. Single-node clusters are not allowed,
for that reason the functional option receives three string arguments: the first node, the second node, and a variadic argument for the rest of the nodes.
The module starts a container for each node, having the first node a reference to the other nodes. E.g. WithNodes("etcd-1", "etcd-2")
, WithNodes("etcd-1", "etcd-2", "etcd-3")
and so on.
The module creates a Docker network for the etcd cluster, and the nodes are connected to this network, so that they can communicate with each other through the network.
WithClusterToken¶
- Not available until the next release of testcontainers-go main
Sets the cluster token for the etcd cluster. The cluster token is used to identify the etcd cluster. The default value is mys3cr3ttok3n
.
The etcd container holds a reference to the cluster token, so you can use it with e.g. ctr.ClusterToken
.
Container Methods¶
- Not available until the next release of testcontainers-go main
The etcd container exposes the following methods:
ClientEndpoint¶
- Not available until the next release of testcontainers-go main
Returns the client endpoint for the etcd container and an error, if any. In the case of a cluster, it returns the client endpoint for the first node.
PeerEndpoint¶
- Not available until the next release of testcontainers-go main
Returns the peer endpoint for the etcd container and an error, if any. In the case of a cluster, it returns the peer endpoint for the first node.