Merge pull request #27927 from kairosci/fix/27823-host-gateway-localhost

fix: use localhost for host.containers.internal in host network mode

libpod/container.go

@@ -1301,7 +1301,16 @@ func (c *Container) NetworkDisabled() (bool, error) {
 }
 
 func (c *Container) HostNetwork() bool {
-	if c.config.CreateNetNS || c.config.NetNsCtr != "" {
+	// If container shares network namespace with another container, check that container
+	if c.config.NetNsCtr != "" {
+		netNsCtr, err := c.runtime.state.Container(c.config.NetNsCtr)
+		if err != nil {
+			return false
+		}
+		return netNsCtr.HostNetwork()
+	}
+
+	if c.config.CreateNetNS {
 		return false
 	}
 	if c.config.Spec.Linux != nil {

libpod/container_internal_common.go

@@ -2427,6 +2427,7 @@ func (c *Container) addHosts() error {
 		NetworkInterface: c.runtime.network,
 		Exclude:          exclude,
 		PreferIP:         preferIP,
+		HostNetwork:      c.HostNetwork(),
 	})
 
 	return etchosts.New(&etchosts.Params{

test/system/500-networking.bats

@@ -773,6 +773,26 @@ nameserver 8.8.8.8" "nameserver order is correct"
     run_podman network rm -f $netname
 }
 
+# https://github.com/containers/podman/issues/27823
+# bats test_tags=ci:parallel
+@test "podman run --network=host uses localhost for host.containers.internal" {
+    run_podman run --rm --network=host $IMAGE cat /etc/hosts
+    assert "$output" =~ "127\.0\.0\.1[[:blank:]].*host\.containers\.internal" \
+           "host.containers.internal should resolve to 127.0.0.1 with --network=host"
+}
+
+# https://github.com/containers/podman/pull/27927
+# bats test_tags=ci:parallel
+@test "podman run in pod with host network uses localhost for host.containers.internal" {
+    local podname="test-pod-hostnet-$(random_string 10)"
+    run_podman pod create --name $podname --network host
+    run_podman run --rm --pod $podname $IMAGE cat /etc/hosts
+    assert "$output" =~ "127\.0\.0\.1[[:blank:]].*host\.containers\.internal" \
+           "host.containers.internal should resolve to 127.0.0.1 in pod with host network"
+    run_podman pod rm $podname
+}
+
+
 # bats test_tags=ci:parallel
 @test "podman run port forward range" {
     # we run a long loop of tests lets run all combinations before bailing out