"Can not connect to Ryuk" on macOS with Docker for Mac 2.4.0.0

I’ve seen this exact error come and go a fair bit on here, but it’s just today started happening for me.

I’m using testcontainers-java 1.12.0, but updating to the latest version has no impact at all.

When running my test, I get the following:

2020-08-28 17:19:18.778,INFO ,[main]:,o.t.d.DockerClientProviderStrategy,,,,,Loaded org.testcontainers.dockerclient.UnixSocketClientProviderStrategy from ~/.testcontainers.properties, will try it first
2020-08-28 17:19:18.833,INFO ,[main]:,o.t.d.DockerClientProviderStrategy,,,,,Will use 'okhttp' transport
2020-08-28 17:19:19.490,INFO ,[main]:,o.t.d.UnixSocketClientProviderStrategy,,,,,Accessing docker with local Unix socket
2020-08-28 17:19:19.491,INFO ,[main]:,o.t.d.DockerClientProviderStrategy,,,,,Found Docker environment with local Unix socket (unix:///var/run/docker.sock)
2020-08-28 17:19:19.492,INFO ,[main]:,o.t.DockerClientFactory,,,,,Docker host IP address is localhost
2020-08-28 17:19:19.680,INFO ,[main]:,o.t.DockerClientFactory,,,,,Connected to docker:
  Server Version: 19.03.13-beta2
  API Version: 1.40
  Operating System: Docker Desktop
  Total Memory: 2996 MB
2020-08-28 17:19:19.988,INFO ,[main]:,o.t.u.RegistryAuthLocator,,,,,Credential helper/store (docker-credential-desktop) does not have credentials for quay.io

And then a seemingly infinite amount of the following:

2020-08-28 17:19:20.733,WARN ,[testcontainers-ryuk]:,o.t.u.ResourceReaper,,,,,Can not connect to Ryuk at localhost:32781
java.net.ConnectException: Connection refused (Connection refused)
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at java.net.Socket.connect(Socket.java:538)
	at java.net.Socket.<init>(Socket.java:434)
	at java.net.Socket.<init>(Socket.java:211)
	at org.testcontainers.utility.ResourceReaper.lambda$start$1(ResourceReaper.java:113)
	at java.lang.Thread.run(Thread.java:748)

This is running with Java 1.8.0_222 from Amazon Corretto, running on macOS 10.15.6.

This definitely worked yesterday. I did have an update to the Docker Engine today, and I’m assuming that’s relevant, but everything else I’m doing with Docker is all working fine - including a different project that uses the Rust version of TestContainers. (Though I notice that doesn’t use Ryuk, which might be relevant)

Cheers