fix(forgejo-runner): job containers must use host network to reach dind

k8s/infra/forgejo-runner/templates/configmap.yaml

@@ -13,6 +13,18 @@
 # runner serves bind-mount arbitrary paths off the runner pod's filesystem
 # into a job container, which is a real widening of the CI trust boundary,
 # not just a convenience.
+#
+# network: host is also only settable here, not per-workflow. A workflow's
+# `container.options: --network host` is silently ignored -- confirmed live:
+# every job's actual `docker create` call logged
+# `network="FORGEJO-ACTIONS-TASK-N_..."`, an auto-generated per-job bridge,
+# regardless of that options string. On that isolated bridge, DOCKER_HOST=
+# tcp://localhost:2376 resolves to the job container itself (no daemon there),
+# not to the dind sidecar, so any docker command that actually needs the
+# daemon (build, push -- anything past docker login, which only talks to the
+# registry over the network and never touches DOCKER_HOST) fails with "Cannot
+# connect to the Docker daemon". host mode puts every job container in dind's
+# own network namespace instead, where the daemon really is listening.
 apiVersion: v1
 kind: ConfigMap
 metadata:
@@ -23,3 +35,4 @@ data:
     container:
       valid_volumes:
         - /docker-certs/client
+      network: host