kubernetes: Adjust for /var/run->/run symlink

PR #2314 turned /var into a tmpfs (possibly overmounted by a persistent disk)
and made /var/run into a symlink to /run. Adjust various containers and bind
mount settings to allow for this change. In particular ensuring that everything
can find the correct shared /var/run/docker.sock, which due to the symlink is
now actually at /run.

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

projects/kubernetes/image-cache/Dockerfile

@@ -12,6 +12,8 @@ RUN apk add --no-cache --initdb -p /out \
 # Remove apk residuals. We have a read-only rootfs, so apk is of no use.
 RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
 
+RUN rmdir /out/var/run && ln -nfs /run /out/var/run
+
 FROM scratch
 WORKDIR /
 COPY --from=build /out /

projects/kubernetes/kube-master.yml

@@ -51,6 +51,7 @@ services:
      - /dev:/dev
      - /etc/resolv.conf:/etc/resolv.conf
      - /lib/modules:/lib/modules
+     - /run:/run:rshared,rbind
      - /var:/var:rshared,rbind
      - /var/lib/kubeadm:/etc/kubernetes
      - /etc/cni:/etc/cni:rshared,rbind

projects/kubernetes/kube-node.yml

@@ -51,6 +51,7 @@ services:
      - /dev:/dev
      - /etc/resolv.conf:/etc/resolv.conf
      - /lib/modules:/lib/modules
+     - /run:/run:rshared,rbind
      - /var:/var:rshared,rbind
      - /var/lib/kubeadm:/etc/kubernetes
      - /etc/cni:/etc/cni:rshared,rbind

projects/kubernetes/kubernetes/Dockerfile

@@ -30,6 +30,8 @@ RUN apk add --no-cache --initdb -p /out \
 # Remove apk residuals. We have a read-only rootfs, so apk is of no use.
 RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
 
+RUN rmdir /out/var/run && ln -nfs /run /out/var/run
+
 RUN curl -fSL -o /tmp/cni.tgz https://github.com/containernetworking/cni/releases/download/v0.5.2/cni-amd64-${cni_version}.tgz && \
     mkdir -p /out/opt/cni/bin /out/etc/cni/net.d && \
     tar -xzf /tmp/cni.tgz -C /out/opt/cni/bin
@@ -47,4 +49,4 @@ 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", "/var:/var:rshared,rbind", "/var/lib/kubeadm:/etc/kubernetes", "/etc/cni:/rootfs/etc/cni:rshared,rbind", "/opt/cni:/rootfs/opt/cni:rshared,rbind"], "mounts": [{"type": "cgroup", "options": ["rw","nosuid","noexec","nodev","relatime"]}], "capabilities": ["all"], "rootfsPropagation": "shared", "pid": "host"}'
+LABEL org.mobyproject.config='{"binds": ["/dev:/dev", "/etc/resolv.conf:/etc/resolv.conf", "/run:/run", "/var:/var:rshared,rbind", "/var/lib/kubeadm:/etc/kubernetes", "/etc/cni:/rootfs/etc/cni:rshared,rbind", "/opt/cni:/rootfs/opt/cni:rshared,rbind"], "mounts": [{"type": "cgroup", "options": ["rw","nosuid","noexec","nodev","relatime"]}], "capabilities": ["all"], "rootfsPropagation": "shared", "pid": "host"}'