NewSDK configurable 'host' about agones

[DazEdword]

Hey folks, thanks for the responses! After doing a bit more reading I think this is not a problem around DIND but rather a particularity of GitLab. That said, I think something along these lines could help in my case:

https://docs.gitlab.com/ee/ci/services/#using-services-with-docker-run-docker-in-docker-side-by-side

I'll give it a go later today and return with more details.

[roberthbailey]

I don't have a particularly strong objection to making the host configurable, but it feels like even with docker-in-docker you should be able to configure the networking so that the two containers share the same network namespace.

I found this medium article that explains How Can Two Containers Communicate Via localhost on Docker? and I've also found some references to using network_mode = "host" in /etc/gitlab-runner/config.toml to allow connections over localhost. It seems like it should be possible to configure the network for this to work (as was found with docker compose in #1183).

[markmandel]

To second @roberthbailey - while I'm not familiar with GitLab's CI, I've definitely done --network=host in DIND.

For example, this Makefile target test-quilkin:
https://github.com/googleforgames/quilkin/blob/81db684cadcd7f28c32306cd4d72116b50ca6e83/build/Makefile#L90-L92

Is run in Google Cloud Build (that is also DIND):
https://github.com/googleforgames/quilkin/blob/81db684cadcd7f28c32306cd4d72116b50ca6e83/cloudbuild.yaml#L26-L29

As a thought, if you can share how you are running your tests on GitLab CI, we can possibly point out a path through. My gut tells me you may need to call docker run --network=host ... directly (rather than indirectly like how Cloud Build does it), but let's see what you have and we can take it from there.

[DazEdword]

Hi again, I've had a look and although I could not go through til the end I'm relatively confident it can work without the custom host, but it's going to affect the way I run the tests anyway. Which btw @markmandel , I've realised I haven't shared yet despite your request, it's been a busy day 😶‍🌫️ .

Basically the way we're running tests is through a dedicated check job in a validation stage. That job will simply translate into running go test ./....

As part of my tests, I have a testcontainers fixture that will create a short-lived containerised game server before the test, and will tear it down after the test. My GitLab config has already some fields for GitLab DIND to play nicely with testcontainers:

  services:
    - name: docker:24.0.7-dind
    # explicitly disable tls to avoid docker startup interruption
      command: ["--tls=false"]
  variables:
    # instruct Testcontainers to use the daemon of DinD, use port 2375 for non-tls connections.
    DOCKER_HOST: "tcp://docker:2375"
    # istruct Docker not to start over TLS.
    DOCKER_TLS_CERTDIR: ""
    # improve performance with overlayfs.
    DOCKER_DRIVER: overlay2
    # Tell Testcontainers that DinD hostname is docker and not localhost
    TC_HOST: docker

My actual testcontainers fixture looks more or less like this:

Setup:

func AgonesSdkContainerFixture(t *testing.T) (context.Context, testcontainers.Container) {
	ctx := context.Background()

	abs, err := filepath.Abs("./")
	require.NoError(t, err)

	gameserverYamlPath := path.Join(abs, "gameserver.yaml")

	req := testcontainers.ContainerRequest{
		Image:        "us-docker.pkg.dev/agones-images/release/agones-sdk:1.37.0",
		ExposedPorts: []string{"9357/tcp", "9358/tcp"},
		WaitingFor:   wait.ForLog("Starting SDKServer grpc-gateway..."),
		HostConfigModifier: func(hc *container.HostConfig) {
			hc.NetworkMode = "host"
			hc.Binds = []string{gameserverYamlPath + ":" + "/tmp/gameserver.yaml"}
		},
		Cmd: []string{"--local", "--feature-gates", "CountsAndLists=true", "-f", "/tmp/gameserver.yaml"},
	}

	agonesC, err := testcontainers.GenericContainer(ctx, testcontainers.GenericContainerRequest{
		ContainerRequest: req,
		Started:          true,
	})
	if err != nil {
		t.Fatal(err)
	}

	return ctx, agonesC
}

Teardown:

func AgonesSdkContainerCleanup(ctx context.Context, t *testing.T, agonesC testcontainers.Container) {
	if err := agonesC.Terminate(ctx); err != nil {
		t.Fatalf("failed to terminate container: %s", err.Error())
	}
}

As I mentioned above, if I go down the GitLab service route, I will then have a single GameServer running alongside my application tests, instead of the ephemeral gameservers that I was aiming to have (I know this is not efficient, but hey test code, I prefer the reliability over the efficiency).

I wouldn't suggest the configurable host if it was production code, but since it's the simple server I think I'd like to maintain my request. Otherwise, if you have suggestions to harmonize GitLab's DIND + network host + ephemeral testcontainers I'll be more than happy to test it out!

Again thanks for your support 👏