Testcontainers

Testcontainers is a NodeJS library that supports tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

Install

npm i -D testcontainers

Usage

Run your app with the DEBUG=testcontainers environment variable set to see debug output.

The following environment variables are supported:

| Key | Example value | Behaviour | | --- | --- | --- | | DOCKER_HOST | tcp://docker:2375 | Override the Docker host, useful for DIND in CI environments |

Common Issues

1. Insufficient Docker memory

By default, Docker sets CPU and memory limits, with a default memory limit of 2GB. If exceeded, you will be unable to pull/run Docker images. To see how much memory Docker has used, you can run docker system info

• To remove existing containers and images to clear some space you can run docker system prune
• Alternatively you can increase the memory limit via Docker's settings under the Advanced pane.

2. Insufficient test timeouts

It can take a few seconds up to a few minutes to pull and run certain Docker images, depending on file sizes and network constraints. It's unlikely that the default timeouts set by test frameworks are sufficient.

• Increase the test timeout via the methods provided by the testing framework.

Examples

Using a pre-built Docker image:

const redis = require("async-redis");
const { GenericContainer } = require("testcontainers");

(async () => {
  const container = await new GenericContainer("redis")
    .withExposedPorts(6379)
    .start();
  
  const redisClient = redis.createClient(
    container.getMappedPort(6379),
    container.getContainerIpAddress(),
  );
  await redisClient.quit();

  await container.stop();
})();

Using a specific image version:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine", "3.10")
  .start();

Building and using your own Docker image:

const path = require("path");
const { GenericContainer } = require("testcontainers");

const buildContext = path.resolve(__dirname, "dir-containing-dockerfile");

const container = await GenericContainer.fromDockerfile(buildContext)
  .withBuildArg("ARG_KEY", "ARG_VALUE")
  .build();

const startedContainer = await container
  .withExposedPorts(8080)
  .start();

Creating a container with a specified name:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withName("custom-container-name")
  .start();

Creating a container with a command:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withCmd(["top"])
  .start();

Execute commands inside a running container:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .start();

const { output, exitCode } = await container.exec(["echo", "hello", "world"]);

Creating a container with bind mounts:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withBindMount("/local/file.txt", "/remote/file.txt")
  .withBindMount("/local/dir", "/remote/dir", "ro")
  .start();

Creating a container with a tmpfs mount:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("postgres")
  .withExposedPorts(5432)
  .withTmpFs({ "/temp_pgdata": "rw,noexec,nosuid,size=65536k" })
  .start();

Creating a container with environment variables:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withEnv("ENV_KEY", "ENV_VALUE")
  .start();

Creating a container with a custom health check command. Note that interval, timeout, retries and startPeriod are optional; the values will be inherited from the image or parent image if omitted. Also note that the wait strategy should be set to Wait.forHealthCheck() for this option to take effect:

const { GenericContainer } = require("testcontainers");
const { Duration, TemporalUnit } = require("node-duration");

const container = await new GenericContainer("alpine")
  .withHealthCheck({
    test: "curl -f http://localhost || exit 1",
    interval: new Duration(1, TemporalUnit.SECONDS),
    timeout: new Duration(3, TemporalUnit.SECONDS),
    retries: 5,
    startPeriod: new Duration(1, TemporalUnit.SECONDS)
  })
  .withWaitStrategy(Wait.forHealthCheck())
  .start();

Creating a container that connects to a specific network:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withNetworkMode("network_name")
  .start();

Pulling an image from the private registry:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("private-image")
  .withAuthentication({
    username: 'username',
    password: 'password',
    email: '[email protected]',
    serveraddress: 'https://index.docker.io/v1'
  })
  .start();

You can override the logging driver used by docker to be the default one (json-file). This might be necessary when the driver of your docker host does not support reading logs and you want to use the Wait.forLogMessage wait strategy.

This is the same as --log-driver json-file on docker run.

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("redis")
  .withDefaultLogDriver()
  .start();

Testcontainers will wait 10 seconds for a container to stop, to override:

const { GenericContainer } = require("testcontainers");
const { Duration, TemporalUnit } = require("node-duration");

const container = await new GenericContainer("postgres")
  .withExposedPorts(5432)
  .start();

await container.stop({ 
  timeout: new Duration(10, TemporalUnit.SECONDS) 
})

Testcontainers will remove associated volumes created by the container when stopped, to override:

const { GenericContainer } = require("testcontainers");

const container = await new GenericContainer("postgres")
  .withExposedPorts(5432)
  .start();

await container.stop({ 
  removeVolumes: false
})

Wait Strategies

Ordinarily Testcontainers will wait for up to 60 seconds for the container's mapped network ports to start listening. If the default 60s timeout is not sufficient, it can be altered with the withStartupTimeout() method:

const { GenericContainer } = require("testcontainers");
const { Duration, TemporalUnit } = require("node-duration");

const container = await new GenericContainer("redis")
  .withExposedPorts(6379)
  .withStartupTimeout(new Duration(100, TemporalUnit.SECONDS))
  .start();

Log output

const { GenericContainer, Wait } = require("testcontainers");

const container = await new GenericContainer("redis")
  .withExposedPorts(6379)
  .withWaitStrategy(Wait.forLogMessage("Ready to accept connections"))
  .start();

Health check

const { GenericContainer, Wait } = require("testcontainers");

const container = await new GenericContainer("redis")
  .withExposedPorts(6379)
  .withWaitStrategy(Wait.forHealthCheck())
  .start();