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

Configuration

The following environment variables are supported:

Key	Example value	Behaviour
`DEBUG`	`testcontainers`	See output
`DEBUG`	`testcontainers:containers`	See container output
`DEBUG`	`testcontainers*`	See all output
`DOCKER_HOST`	`tcp://docker:2375`	Override the Docker host
`TESTCONTAINERS_RYUK_DISABLED`	`true`	Disable ryuk

Modules

Check if there already exists a pre-prepared module for your use-case.

Examples

Using a pre-built Docker image:

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

describe("GenericContainer", () => {
  let container;
  let redisClient;

  beforeAll(async () => {
    container = await new GenericContainer("redis")
      .withExposedPorts(6379)
      .start();

    redisClient = redis.createClient(
      container.getMappedPort(6379),
      container.getContainerIpAddress(),
    );
  });

  afterAll(async () => {
    await redisClient.quit();
    await container.stop();
  });

  it("works", async () => {
    await redisClient.set("key", "val");
    expect(await redisClient.get("key")).toBe("val");
  });
});

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();

Using a custom Dockerfile name:

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

const container = await GenericContainer.fromDockerfile(buildContext, "my-dockerfile")
  .build();

Creating a container with multiple exposed ports:

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

const container = await new GenericContainer("alpine")
  .withExposedPorts(22, 80, 443)
  .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"]);

Stream logs from a running container:

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

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

const stream = await container.logs();
stream
    .on("data", line => console.log(line))
    .on("err", line => console.error(line))
    .on("end", () => console.log("Stream closed"));

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, Wait } = require("testcontainers");

const container = await new GenericContainer("alpine")
  .withHealthCheck({
    test: "curl -f http://localhost || exit 1",
    interval: 1000,
    timeout: 3000,
    retries: 5,
    startPeriod: 1000
  })
  .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();

Create user-defined bridge network and attach the container to it:

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

const network = await new Network()
    .start();

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

await container.stop();
await network.stop();

Specifying a pull policy.

Note that if omitted will use the DefaultPullPolicy which will use a locally cached image if one already exists, this is usually the preferred option. In cases where there is a local image for a given tag but the remote image with the same tag may have changed (for example when using the latest tag), you can tell testcontainers to pull the image again by specifying an AlwaysPullPolicy:

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

const container = await new GenericContainer("alpine", "latest")
  .withPullPolicy(new AlwaysPullPolicy())
  .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: 'your@email.email',
    serveraddress: 'https://index.docker.io/v1'
  })
  .start();

Specifying a default log driver.

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();

Creating a container with privileged mode:

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

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

Testcontainers will not wait for a container to stop, to override:

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

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

await container.stop({ 
  timeout: 10000 
})

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
})

Docker Compose

Testcontainers supports docker-compose. For example for the following docker-compose.yml:

version: "3"

services:
  redis:
    image: redis:latest
    ports:
      - 6379
  postgres:
    image: postgres:latest
    ports:
      - 5432

You can start and stop the environment, and interact with its containers:

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

describe("DockerComposeEnvironment", () => {
  let environment;
  let redisClient;

  beforeAll(async () => {
    const composeFilePath = path.resolve(__dirname, "dir-containing-docker-compose-yml");
    const composeFile = "docker-compose.yml";

    environment = await new DockerComposeEnvironment(composeFilePath, composeFile).up();

    const redisContainer = environment.getContainer("redis_1");
    redisClient = redis.createClient(
      redisContainer.getMappedPort(6379),
      redisContainer.getContainerIpAddress(),
    );
  });

  afterAll(async () => {
    await redisClient.quit();
    await environment.down();
  });

  it("works", async () => {
    await redisClient.set("key", "val");
    expect(await redisClient.get("key")).toBe("val");
  });
});

Create the containers with their own wait strategies:

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

const environment = await new DockerComposeEnvironment(composeFilePath, composeFile)
  .withWaitStrategy("redis_1", Wait.forLogMessage("Ready to accept connections"))
  .withWaitStrategy("postgres_1", Wait.forHealthCheck())
  .up();

Once the environment has started, you can interact with the containers as you would any other GenericContainer:

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

const environment = await new DockerComposeEnvironment(composeFilePath, composeFile).up();

const container = environment.getContainer("alpine_1");
const { output, exitCode } = await container.exec(["echo", "hello", "world"]);

If you have multiple docker-compose environments which share dependencies such as networks, you can stop the environment instead of downing it:

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

const environment = await new DockerComposeEnvironment(composeFilePath, composeFile).up();

await environment.stop();

By default docker-compose does not re-build Dockerfiles, but you can override this behaviour:

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

const environment = await new DockerComposeEnvironment(composeFilePath, composeFile)
  .withBuild()
  .up();

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 container = await new GenericContainer("redis")
  .withExposedPorts(6379)
  .withStartupTimeout(120000)
  .start();

Log output

Plain text:

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

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

Regular expression:

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

const container = await new GenericContainer("redis")
  .withExposedPorts(6379)
  .withWaitStrategy(Wait.forLogMessage(/Listening on port [0-9]+/))
  .start();

Health check

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

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

ryuk

Testcontainers will start a sidecar container called ryuk whenever a container, docker-compose environment or network is started. This container keeps track of containers/images/networks/volumes created by testcontainers and will automatically clean up these resources 10s after connectivity with testcontainers is lost.

This is useful for example if a test starts a container and then terminates unexpectedly, as these dangling resources will be automatically removed.

ryuk must be run with privileged mode; in CI environments such as Bit Bucket where this isn't supported, ryuk can be disabled by setting the environment variable TESTCONTAINERS_RYUK_DISABLED to true.

Common Issues

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.

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.

ponimas/testcontainers-node