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Custom configuration

You can override some default properties if your environment requires that.

Configuration locations

The configuration will be loaded from multiple locations. Properties are considered in the following order:

  1. Environment variables
  2. in user's home folder. Example locations:
    Linux: /home/myuser/
    Windows: C:/Users/myuser/
    macOS: /Users/myuser/
  3. on the classpath.

Note that when using environment variables, configuration property names should be set in upper case with underscore separators, preceded by TESTCONTAINERS_ - e.g. checks.disable becomes TESTCONTAINERS_CHECKS_DISABLE.

The classpath file may exist within the local codebase (e.g. within the src/test/resources directory) or within library dependencies that you may have. Any such configuration files will have their contents merged. If any keys conflict, the value will be taken on the basis of the first value found in:

  • 'local' classpath (i.e. where the URL of the file on the classpath begins with file:), then
  • other classpath locations (i.e. JAR files) - considered in alphabetical order of path to provide deterministic ordering.

Disabling the startup checks

checks.disable = [true|false]

Before running any containers Testcontainers will perform a set of startup checks to ensure that your environment is configured correctly. Usually they look like this:

        ℹ︎ Checking the system...
        ✔ Docker version should be at least 1.6.0
        ✔ File should be mountable
        ✔ A port exposed by a docker container should be accessible
It takes a couple of seconds, but if you want to speed up your tests, you can disable the checks once you have everything configured. Add checks.disable=true to your $HOME/ to completely disable them.

Customizing images


This approach is discouraged and deprecated, but is documented for completeness. Overriding individual image names via configuration may be removed in 2021. See Image Name Substitution for other strategies for substituting image names to pull from other registries.

Testcontainers uses public Docker images to perform different actions like startup checks, VNC recording and others. Some companies disallow the usage of Docker Hub, but you can override *.image properties with your own images from your private registry to workaround that.

ryuk.container.image = testcontainers/ryuk:0.3.3 Performs fail-safe cleanup of containers, and always required (unless Ryuk is disabled)

tinyimage.container.image = alpine:3.17
Used to check whether images can be pulled at startup, and always required (unless startup checks are disabled)

sshd.container.image = testcontainers/sshd:1.1.0
Required if exposing host ports to containers

vncrecorder.container.image = testcontainers/vnc-recorder:1.3.0 Used by VNC recorder in Testcontainers' Selenium integration

socat.container.image = alpine/socat
compose.container.image = docker/compose:1.8.0
Required if using Docker Compose

kafka.container.image = confluentinc/cp-kafka
Used by KafkaContainer

localstack.container.image = localstack/localstack
Used by LocalStack

pulsar.container.image = apachepulsar/pulsar:2.2.0
Used by Apache Pulsar

Customizing Ryuk resource reaper

ryuk.container.image = testcontainers/ryuk:0.3.3 The resource reaper is responsible for container removal and automatic cleanup of dead containers at JVM shutdown

ryuk.container.privileged = true In some environments ryuk must be started in privileged mode to work properly (--privileged flag)

Disabling Ryuk

Ryuk must be started as a privileged container.
If your environment already implements automatic cleanup of containers after the execution, but does not allow starting privileged containers, you can turn off the Ryuk container by setting TESTCONTAINERS_RYUK_DISABLED environment variable to true.


Note that Testcontainers will continue doing the cleanup at JVM's shutdown, unless you kill -9 your JVM process.

Customizing image pull behaviour

pull.pause.timeout = 30 By default Testcontainers will abort the pull of an image if the pull appears stalled (no data transferred) for longer than this duration (in seconds).

Customizing client ping behaviour = 5 Specifies for how long Testcontainers will try to connect to the Docker client to obtain valid info about the client before giving up and trying next strategy, if applicable (in seconds).

Customizing Docker host detection

Testcontainers will attempt to detect the Docker environment and configure everything to work automatically.

However, sometimes customization is required. Testcontainers will respect the following environment variables:

DOCKER_HOST = unix:///var/run/docker.sock
See Docker environment variables

Path to Docker's socket. Used by Ryuk, Docker Compose, and a few other containers that need to perform Docker actions.
Example: /var/run/docker-alt.sock

Docker's host on which ports are exposed.
Example: docker.svc.local

For advanced users, the Docker host connection can be configured via configuration in ~/ Note that these settings require use of the EnvironmentAndSystemPropertyClientProviderStrategy. The example below illustrates usage:

docker.client.strategy=org.testcontainers.dockerclient.EnvironmentAndSystemPropertyClientProviderStrategy\://\:1234     # Equivalent to the DOCKER_HOST environment variable. Colons should be escaped.
docker.tls.verify=1                         # Equivalent to the DOCKER_TLS_VERIFY environment variable
docker.cert.path=/some/path                 # Equivalent to the DOCKER_CERT_PATH environment variable
In addition, you can deactivate this behaviour by specifying:
dockerconfig.source=autoIgnoringUserProperties # 'auto' by default