kubernetes: populate host CNI paths by binding from kubernetes service.

Kubernetes assumes (for now) that various paths are valid at the host level to
be mounted into containers, including /opt/cni and /etc/cni.

We cannot (easily) use symlinks here because the weave.yml mounts /opt and /etc
rather than /opt/cni and /etc/cni (this seems likely to be common pattern). So
if /etc/cni were a symlink to the persistent disk (under /var/lib) then it will
be dangling link within the weave container.

So add bind mounts to the runtime configuration of the kubernetes image. This
also means we must create the target mount points in the yml.

Signed-off-by: Ian Campbell <ijc@docker.com>

projects/kubernetes/kube-master.yml

@@ -60,6 +60,10 @@ services:
   - name: kubelet
     image: linuxkitprojects/kubernetes:c4a6ae5121df50471ad244b9fc153ff5eb674fb2
 files:
+  - path: /opt/cni
+    directory: true
+  - path: /etc/cni
+    directory: true
   - path: root/.ssh/authorized_keys
     source: ~/.ssh/id_rsa.pub
     mode: "0600"

projects/kubernetes/kube-node.yml

@@ -58,6 +58,10 @@ services:
   - name: kubelet
     image: linuxkitprojects/kubernetes:c4a6ae5121df50471ad244b9fc153ff5eb674fb2
 files:
+  - path: /opt/cni
+    directory: true
+  - path: /etc/cni
+    directory: true
   - path: root/.ssh/authorized_keys
     source: ~/.ssh/id_rsa.pub
     mode: "0600"

projects/kubernetes/kubernetes/Dockerfile

@@ -45,4 +45,4 @@ WORKDIR /
 ENTRYPOINT ["/usr/bin/kubelet.sh"]
 COPY --from=build /out /
 ENV KUBECONFIG "/etc/kubernetes/admin.conf"
-LABEL org.mobyproject.config='{"binds": ["/dev:/dev", "/etc/resolv.conf:/etc/resolv.conf", "/run:/run", "/var:/var:rshared,rbind", "/var/lib/kubeadm:/etc/kubernetes"], "mounts": [{"type": "cgroup", "options": ["rw","nosuid","noexec","nodev","relatime"]}], "capabilities": ["all"], "rootfsPropagation": "shared", "pid": "host", "runtime": {"mkdir": ["/var/lib/kubeadm", "/var/lib/cni/etc", "/var/lib/cni/opt"]}}'
+LABEL org.mobyproject.config='{"binds": ["/dev:/dev", "/etc/resolv.conf:/etc/resolv.conf", "/run:/run", "/var:/var:rshared,rbind", "/var/lib/kubeadm:/etc/kubernetes"], "mounts": [{"type": "cgroup", "options": ["rw","nosuid","noexec","nodev","relatime"]}], "capabilities": ["all"], "rootfsPropagation": "shared", "pid": "host", "runtime": {"mkdir": ["/var/lib/kubeadm", "/var/lib/cni/etc", "/var/lib/cni/opt"], "mounts": [{"type": "bind", "source": "/var/lib/cni/opt", "destination": "/opt/cni", "options": ["rw", "bind"]}, {"type": "bind", "source": "/var/lib/cni/etc", "destination": "/etc/cni", "options": ["rw", "bind"]}]}}'