Unnecessary docker registry check crashes when offline

[JakobJingleheimer]

Expected Behaviour

It should work offline (there is no need to make any network calls).

Actual Behaviour

It crashes

Testcontainer Logs
...

Steps to Reproduce

1. Use the default setup from PostgreSqlContainer (IMAGE = 'postgres:16')
2. Run docker pull postgres:16
3. Disable internet

Error: (HTTP code 500) server error - failed to resolve reference "docker.io/library/postgres:16": failed to request Head …

Environment Information

• Operating System: macOS 15.5
• Docker Version: 28.3.2
• Node version: 24.3.0
• Testcontainers version: 11.5.1

[cristianrgreco]

Makes sense, the check seems unnecessary. PR welcome

[JakobJingleheimer]

When pulling the image, it has a gate:

testcontainers-node/packages/testcontainers/src/container-runtime/utils/pull-image.ts

Lines 19 to 22 in c81b942

	if (!options.force && (await imageExists(dockerode, options.imageName))) {
	log.debug(`Not pulling image "${options.imageName}" as it already exists`);
	return;
	}

So I'm thinking it's perhaps earlier at build:

testcontainers-node/packages/testcontainers/src/generic-container/generic-container-builder.ts

Lines 60 to 71 in c81b942

	public async build(
	image = `localhost/${this.uuid.nextUuid()}:${this.uuid.nextUuid()}`,
	options: BuildOptions = { deleteOnExit: true }
	): Promise<GenericContainer> {
	const client = await getContainerRuntimeClient();
	const reaper = await getReaper(client);
	const imageName = ImageName.fromString(image);
	const dockerfile = path.resolve(this.context, this.dockerfileName);
	const imageNames = await getDockerfileImages(dockerfile, this.buildArgs);
	const registryConfig = await this.getRegistryConfig(client.info.containerRuntime.indexServerAddress, imageNames);

which eventually takes me to

testcontainers-node/packages/testcontainers/src/container-runtime/auth/get-auth-config.ts

Lines 42 to 49 in c81b942

	export const getAuthConfig = async (registry: string): Promise<AuthConfig | undefined> => {
	if (authsCache.has(registry)) {
	log.debug(`Auth config cache hit for registry "${registry}"`);
	return authsCache.get(registry);
	}
	for (const registryAuthLocator of registryAuthLocators) {
	const authConfig = await registryAuthLocator.getAuthConfig(registry, await dockerConfig);

and then it kind of goes down a rabbit-hole.

Since I already have it built, it doesn't hit that branch, so I can't check the debugging output. Could you let me know if I'm on the correct path and if so, how to clear the build so I hit that branch and confirm?

[cristianrgreco]

Released in 11.6.0.

[JakobJingleheimer]

Awesome, thanks!