Add Docker caching support to CoreOS' clusters.

a more idiomatic take on #4378. as a bonus, and to be nice on
    resources, an ultra lightweight docker-registry container is
    consumed.

Signed-off-by: António Meireles <antonio.meireles@reformi.st>

docs/getting-started-guides/aws/cloud-configs/master.yaml

@@ -104,6 +104,39 @@ coreos:
         ExecStartPre=/usr/bin/chmod +x /opt/bin/flanneld
         ExecStartPre=-/usr/bin/etcdctl mk /coreos.com/network/config '{"Network":"10.244.0.0/16", "Backend": {"Type": "vxlan"}}'
         ExecStart=/opt/bin/flanneld
+    - name: docker-cache.service
+      command: start
+      content: |
+        [Unit]
+        Description=Docker cache proxy
+        Requires=early-docker.service
+        After=early-docker.service
+        Before=early-docker.target
+
+        [Service]
+        Restart=always
+        TimeoutStartSec=0
+        RestartSec=5
+        Environment="TMPDIR=/var/tmp/"
+        Environment="DOCKER_HOST=unix:///var/run/early-docker.sock"
+        ExecStartPre=-/usr/bin/docker kill docker-registry
+        ExecStartPre=-/usr/bin/docker rm docker-registry
+        ExecStartPre=/usr/bin/docker pull quay.io/devops/docker-registry:latest
+        ExecStart=/usr/bin/docker run --rm --net host --name docker-registry \
+            -e STANDALONE=false \
+            -e MIRROR_SOURCE=https://registry-1.docker.io \
+            -e MIRROR_SOURCE_INDEX=https://index.docker.io \
+            -e MIRROR_TAGS_CACHE_TTL=1800 \
+            quay.io/devops/docker-registry:latest
+    - name: docker.service
+      drop-ins:
+        - name: 51-docker-mirror.conf
+          content: |
+            [Unit]
+            Requires=docker-cache.service
+            After=docker-cache.service
+            [Service]
+            Environment=DOCKER_OPTS='--registry-mirror=http://$private_ipv4:5000'
     - name: kube-apiserver.service
       command: start
       content: |

docs/getting-started-guides/aws/cloud-configs/node.yaml

@@ -34,20 +34,11 @@ coreos:
         ExecStart=/opt/bin/flanneld -etcd-endpoints http://<master-private-ip>:4001
     - name: docker.service
       command: start
-      content: |
+      drop-ins:
-        [Unit]
+        - name: 51-docker-mirror.conf
-        After=flannel.service
+          content: |
-        Wants=flannel.service
+            [Service]
-        Description=Docker Application Container Engine
+            Environment=DOCKER_OPTS='--registry-mirror=http://<master-private-ip>:5000'
-        Documentation=http://docs.docker.io
-
-        [Service]
-        EnvironmentFile=/run/flannel/subnet.env
-        ExecStartPre=/bin/mount --make-rprivate /
-        ExecStart=/usr/bin/docker -d --bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU} -s=overlay -H fd://
-
-        [Install]
-        WantedBy=multi-user.target
     - name: setup-network-environment.service
       command: start
       content: |

docs/getting-started-guides/coreos/cloud-configs/master.yaml

@@ -104,6 +104,39 @@ coreos:
         ExecStartPre=/usr/bin/chmod +x /opt/bin/flanneld
         ExecStartPre=-/usr/bin/etcdctl mk /coreos.com/network/config '{"Network":"10.244.0.0/16", "Backend": {"Type": "vxlan"}}'
         ExecStart=/opt/bin/flanneld
+    - name: docker-cache.service
+      command: start
+      content: |
+        [Unit]
+        Description=Docker cache proxy
+        Requires=early-docker.service
+        After=early-docker.service
+        Before=early-docker.target
+
+        [Service]
+        Restart=always
+        TimeoutStartSec=0
+        RestartSec=5
+        Environment="TMPDIR=/var/tmp/"
+        Environment="DOCKER_HOST=unix:///var/run/early-docker.sock"
+        ExecStartPre=-/usr/bin/docker kill docker-registry
+        ExecStartPre=-/usr/bin/docker rm docker-registry
+        ExecStartPre=/usr/bin/docker pull quay.io/devops/docker-registry:latest
+        ExecStart=/usr/bin/docker run --rm --net host --name docker-registry \
+            -e STANDALONE=false \
+            -e MIRROR_SOURCE=https://registry-1.docker.io \
+            -e MIRROR_SOURCE_INDEX=https://index.docker.io \
+            -e MIRROR_TAGS_CACHE_TTL=1800 \
+            quay.io/devops/docker-registry:latest
+    - name: docker.service
+      drop-ins:
+        - name: 51-docker-mirror.conf
+          content: |
+            [Unit]
+            Requires=docker-cache.service
+            After=docker-cache.service
+            [Service]
+            Environment=DOCKER_OPTS='--registry-mirror=http://$private_ipv4:5000'
     - name: kube-apiserver.service
       command: start
       content: |

docs/getting-started-guides/coreos/cloud-configs/node.yaml

@@ -22,7 +22,7 @@ coreos:
       command: start
       content: |
         [Unit]
-        After=network-online.target 
+        After=network-online.target
         Wants=network-online.target
         Description=flannel is an etcd backed overlay network for containers
 
@@ -34,20 +34,11 @@ coreos:
         ExecStart=/opt/bin/flanneld -etcd-endpoints http://<master-private-ip>:4001
     - name: docker.service
       command: start
-      content: |
+      drop-ins:
-        [Unit]
+        - name: 51-docker-mirror.conf
-        After=flannel.service
+          content: |
-        Wants=flannel.service
+            [Service]
-        Description=Docker Application Container Engine
+            Environment=DOCKER_OPTS='--registry-mirror=http://<master-private-ip>:5000'
-        Documentation=http://docs.docker.io
-
-        [Service]
-        EnvironmentFile=/run/flannel/subnet.env
-        ExecStartPre=/bin/mount --make-rprivate /
-        ExecStart=/usr/bin/docker -d --bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU} -s=overlay -H fd://
-
-        [Install]
-        WantedBy=multi-user.target
     - name: setup-network-environment.service
       command: start
       content: |

docs/getting-started-guides/coreos/cloud-configs/standalone.yaml

@@ -49,22 +49,40 @@ coreos:
         ExecStartPre=/usr/bin/chmod +x /opt/bin/flanneld
         ExecStartPre=-/usr/bin/etcdctl mk /coreos.com/network/config '{"Network":"10.244.0.0/16", "Backend": {"Type": "vxlan"}}'
         ExecStart=/opt/bin/flanneld
-    - name: docker.service
+    - name: docker-cache.service
       command: start
       content: |
         [Unit]
-        After=flannel.service
+        Description=Docker cache proxy
-        Wants=flannel.service
+        Requires=early-docker.service
-        Description=Docker Application Container Engine
+        After=early-docker.service
-        Documentation=http://docs.docker.io
+        Before=early-docker.target
 
         [Service]
-        EnvironmentFile=/run/flannel/subnet.env
+        Restart=always
-        ExecStartPre=/bin/mount --make-rprivate /
+        TimeoutStartSec=0
-        ExecStart=/usr/bin/docker -d --bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU} -s=overlay -H fd://
+        RestartSec=5
-
+        Environment="TMPDIR=/var/tmp/"
-        [Install]
+        Environment="DOCKER_HOST=unix:///var/run/early-docker.sock"
-        WantedBy=multi-user.target
+        ExecStartPre=-/usr/bin/docker kill docker-registry
+        ExecStartPre=-/usr/bin/docker rm docker-registry
+        ExecStartPre=/usr/bin/docker pull quay.io/devops/docker-registry:latest
+        ExecStart=/usr/bin/docker run --rm --net host --name docker-registry \
+            -e STANDALONE=false \
+            -e MIRROR_SOURCE=https://registry-1.docker.io \
+            -e MIRROR_SOURCE_INDEX=https://index.docker.io \
+            -e MIRROR_TAGS_CACHE_TTL=1800 \
+            quay.io/devops/docker-registry:latest
+    - name: docker.service
+      command: start
+      drop-ins:
+        - name: 51-docker-mirror.conf
+          content: |
+            [Unit]
+            Requires=docker-cache.service
+            After=docker-cache.service
+            [Service]
+            Environment=DOCKER_OPTS='--registry-mirror=http://$private_ipv4:5000'
     - name: kube-apiserver.service
       command: start
       content: |