build_from_dockerfile.md

Build from Dockerfile

Testcontainers for Go gives you the ability to build an image and run a container from a Dockerfile.

You can do so by specifying a Context (the filepath to the build context on your local filesystem) and optionally a Dockerfile (defaults to "Dockerfile") like so:

req := ContainerRequest{
		FromDockerfile: testcontainers.FromDockerfile{
			Context: "/path/to/build/context",
			Dockerfile: "CustomDockerfile",
		},
	}

If your Dockerfile expects build args:

FROM alpine

ARG FOO

You can specify them like:

req := ContainerRequest{
		FromDockerfile: testcontainers.FromDockerfile{
			Context: "/path/to/build/context",
			Dockerfile: "CustomDockerfile",
			BuildArgs: map[string]*string {
				"FOO": "BAR",
			},
		},
	}

Dynamic Build Context

If you would like to send a build context that you created in code (maybe you have a dynamic Dockerfile), you can send the build context as an io.Reader since the Docker Daemon accepts it as a tar file, you can use the tar package to create your context.

To do this you would use the ContextArchive attribute in the FromDockerfile struct.

var buf bytes.Buffer
tarWriter := tar.NewWriter(&buf)
// ... add some files
if err := tarWriter.Close(); err != nil {
	// do something with err
}
reader := bytes.NewReader(buf.Bytes())
fromDockerfile := testcontainers.FromDockerfile{
	ContextArchive: reader,
}

Please Note if you specify a ContextArchive this will cause Testcontainers for Go to ignore the path passed in to Context.

Images requiring auth

If you are building a local Docker image that is fetched from a Docker image in a registry requiring authentication (e.g., assuming you are fetching from a custom registry such as myregistry.com), you will need to specify the credentials to succeed, as follows:

req := ContainerRequest{
    FromDockerfile: testcontainers.FromDockerfile{
        Context: "/path/to/build/context",
        Dockerfile: "CustomDockerfile",
		AuthConfigs:   map[string]types.AuthConfig{
            "https://myregistry.com": {
                Username: "myusername",
                Password: "mypassword",
            },
        },
	},
}