GenericContainer does not start up with podman in host networking mode

[kirankolli82]

I am running an IntegrationTest using TestContainers version 1.21.3 on a rootless podman setup.
On Startup a GenericContainer is running an assertion that asserts that the ports exposed post container startup match the container definition. This assertions depends on running a container inspect command which in case of podman is podman inspect.
The problem is that when I start a rootless podman , podman chooses the host networking on its own and in that mode when you run podman inspect the NetworkSettings are empty. This always fails the assertion being made the "testcontainers" library (GenericContainer : Line 457).

Is this a bug ? How do I get around this issue ?

Podman Inspect output looks like this :

[
 {
  "Id" : xxxx
   .....
   "NetworkSettings": {
        ......
        "Ports": {},
         "Networks": {
            "host": {
               .. all field values null ...
             }
          }
     }
]

Podman version : 5.4.0

[GabrielBBaldez]

This isn't really a Testcontainers bug — it's how host networking works.

In host mode the container shares the host's network namespace, so there's no port publishing/mapping — the container's ports are the host's ports. That's why podman inspect returns empty NetworkSettings: there's nothing to map. Testcontainers, on the other hand, is built around mapped ports — GenericContainer exposes a port and then resolves the random host port via getMappedPort() from the inspect output. With host networking there's nothing to resolve, so the port-mapping check fails. In other words, host networking is fundamentally incompatible with Testcontainers' mapped-port model.

The fix is to let the container use the default/bridge network so ports get published. Rootless Podman normally uses slirp4netns/pasta (which does publish ports) and shouldn't pick host on its own, so something is forcing it. Check your containers.conf (~/.config/containers/containers.conf and /etc/containers/containers.conf) for a default such as:

[containers]
netns = "host"

Remove/override that so containers fall back to the default rootless network, and podman inspect will report the published ports again. If you genuinely need host networking for a specific container, Testcontainers' mapped-port APIs won't apply to it — you'd address it on a fixed host port instead.