I’ve just encountered this same problem, and am very curious as to what the solution is?
Deploying test containers on completely different infrastructure just to confirm they respond seems unnecessarily unwieldy when there is a docker service built into Circle
As you can see, the container starts successfully but can’t be curled by the test environment.
I thought perhaps the issue was that priveleged ports such as 80 might not be accessible for some reason, and implemented variable port substitution so I could attempt to check connectivity to localhost on arbitrary ports (in this case 8080), but that has the same problem.