dockertest

Write better integration tests! Dockertest helps you boot up ephermal docker images for your Go tests with minimal work.

Description

Use Docker to run your Golang integration tests against third party services on Microsoft Windows, Mac OSX and Linux!

Table of Contents

Programming language: Go

License: Apache License 2.0

Tags: Testing     Testing Frameworks     Go    

README

Use Docker to run your Golang integration tests against third party services on Microsoft Windows, Mac OSX and Linux!

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Table of Contents

• Why should I use Dockertest?
• Installing and using Dockertest
  • Using Dockertest
  • Examples
• Troubleshoot & FAQ
  • Out of disk space
  • Removing old containers

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Why should I use Dockertest?

When developing applications, it is often necessary to use services that talk to a database system. Unit Testing these services can be cumbersome because mocking database/DBAL is strenuous. Making slight changes to the schema implies rewriting at least some, if not all of the mocks. The same goes for API changes in the DBAL. To avoid this, it is smarter to test these specific services against a real database that is destroyed after testing. Docker is the perfect system for running unit tests as you can spin up containers in a few seconds and kill them when the test completes. The Dockertest library provides easy to use commands for spinning up Docker containers and using them for your tests.

Installing and using Dockertest

Using Dockertest is straightforward and simple. Check the releases tab for available releases.

To install dockertest, run

go get -u github.com/ory/dockertest/v3

or

dep ensure -add github.com/ory/[email protected]

Using Dockertest

package dockertest_test

import (
    "database/sql"
    "fmt"
    "log"
    "os"
    "testing"

    _ "github.com/go-sql-driver/mysql"
    "github.com/ory/dockertest/v3"
)

var db *sql.DB

func TestMain(m *testing.M) {
    // uses a sensible default on windows (tcp/http) and linux/osx (socket)
    pool, err := dockertest.NewPool("")
    if err != nil {
        log.Fatalf("Could not connect to docker: %s", err)
    }

    // pulls an image, creates a container based on it and runs it
    resource, err := pool.Run("mysql", "5.7", []string{"MYSQL_ROOT_PASSWORD=secret"})
    if err != nil {
        log.Fatalf("Could not start resource: %s", err)
    }

    // exponential backoff-retry, because the application in the container might not be ready to accept connections yet
    if err := pool.Retry(func() error {
        var err error
        db, err = sql.Open("mysql", fmt.Sprintf("root:secret@(localhost:%s)/mysql", resource.GetPort("3306/tcp")))
        if err != nil {
            return err
        }
        return db.Ping()
    }); err != nil {
        log.Fatalf("Could not connect to database: %s", err)
    }

    code := m.Run()

    // You can't defer this because os.Exit doesn't care for defer
    if err := pool.Purge(resource); err != nil {
        log.Fatalf("Could not purge resource: %s", err)
    }

    os.Exit(code)
}

func TestSomething(t *testing.T) {
    // db.Query()
}

Examples

We provide code examples for well known services in the [examples](examples/) directory, check them out!

Troubleshoot & FAQ

Out of disk space

Try cleaning up the images with docker-cleanup-volumes.

Removing old containers

Sometimes container clean up fails. Check out this stackoverflow question on how to fix this. You may also set an absolute lifetime on containers:

resource.Expire(60) // Tell docker to hard kill the container in 60 seconds

To let stopped containers removed from file system automatically, use pool.RunWithOptions() instead of pool.Run() with config.AutoRemove set to true, e.g.:

postgres, err := pool.RunWithOptions(&dockertest.RunOptions{
    Repository: "postgres",
    Tag:        "11",
    Env: []string{
        "POSTGRES_USER=test",
        "POSTGRES_PASSWORD=test",
        "listen_addresses = '*'",
    },
}, func(config *docker.HostConfig) {
    // set AutoRemove to true so that stopped container goes away by itself
    config.AutoRemove = true
    config.RestartPolicy = docker.RestartPolicy{
        Name: "no",
    }
})

Running dockertest in Gitlab CI

How to run dockertest on shared gitlab runners?

You should add docker dind service to your job which starts in sibling container. That means database will be available on host docker.
You app should be able to change db host through environment variable.

Here is the simple example of gitlab-ci.yml:

stages:
  - test
go-test:
  stage: test
  image: golang:1.15
  services:
    - docker:dind
  variables:
    DOCKER_HOST: tcp://docker:2375
    DOCKER_DRIVER: overlay2
    YOUR_APP_DB_HOST: docker
  script:
    - go test ./...

Plus in the pool.Retry method that checks for connection readiness, you need to use $YOUR_APP_DB_HOST instead of localhost.

How to run dockertest on group(custom) gitlab runners?

Gitlab runner can be run in docker executor mode to save compatibility with shared runners.
Here is the simple register command:

```shell script gitlab-runner register -n \ --url https://gitlab.com/ \ --registration-token $YOUR_TOKEN \ --executor docker \ --description "My Docker Runner" \ --docker-image "docker:19.03.12" \ --docker-privileged

You only need to instruct docker dind to start with disabled tls.  
Add variable `DOCKER_TLS_CERTDIR: ""` to `gitlab-ci.yml` above. It will tell
docker daemon to start on 2375 port over http.

### How to run dockertest with remote Docker

Use-case: locally installed docker CLI (client), docker daemon somewhere
remotely, environment properly set (ie: `DOCKER_HOST`, etc..). For example,
remote docker can be provisioned by docker-machine.

Currently, dockertest in case of `resource.GetHostPort()` will return docker
host binding address (commonly - `localhost`) instead of remote docker host.
Universal solution is:

```go
func getHostPort(resource *dockertest.Resource, id string) string {
    dockerURL := os.Getenv("DOCKER_HOST")
    if dockerURL == "" {
        return resource.GetHostPort(id)
    }
    u, err := url.Parse(dockerURL)
    if err != nil {
        panic(err)
    }
    return u.Hostname() + ":" + resource.GetPort(id)
}

It will return the remote docker host concatenated with the allocated port in case DOCKER_HOST env is defined. Otherwise, it will fall back to the embedded behavior.