configure flannel via systemd unit

send flannel json to etcd via systemd unit rather than
cloud-init script

fragments/flannel-config.service.yaml

@@ -0,0 +1,46 @@
+#cloud-config
+merge_how: dict(recurse_array)+list(append)
+write_files:
+  - path: /usr/local/bin/flannel-config
+    owner: "root:root"
+    permissions: "0755"
+    content: |
+      #!/bin/sh
+      
+      : ${FLANNEL_JSON:=/etc/sysconfig/flannel-network.json}
+
+      if ! [ -f "$FLANNEL_JSON" ]; then
+        echo "ERROR: missing network configuration file" >&2
+        exit 1
+      fi
+
+      if ! [ "$FLANNEL_ETCD" ] && [ "$FLANNEL_ETCD_KEY" ]; then
+        echo "ERROR: missing required configuration" >&2
+        exit 1
+      fi
+      
+      echo "creating flanneld config in etcd"
+      while ! curl -sf -L $FLANNEL_ETCD/v2/keys${FLANNEL_ETCD_KEY}/config \
+        -X PUT --data-urlencode value@${FLANNEL_JSON}; do
+          echo "waiting for etcd"
+          sleep 1
+      done
+  - path: /etc/systemd/system/flannel-config.service
+    owner: "root:root"
+    permissions: "0644"
+    content: |
+      [Unit]
+      After=etcd.service
+      Requires=etcd.service
+
+      [Service]
+      Type=oneshot
+      EnvironmentFile=/etc/sysconfig/flanneld
+      ExecStart=/usr/local/bin/flannel-config
+
+      [Install]
+      WantedBy=multi-user.target
+runcmd:
+  - systemctl enable flannel-config
+  - systemctl start --no-block flannel-config
+

fragments/write-flannel-config.sh

@@ -30,15 +30,3 @@ cat >> $FLANNEL_JSON <<EOF
 }
 EOF
 
-# wait for etcd to become active (we will need it to push the flanneld config)
-while ! curl -sf -o /dev/null $FLANNEL_ETCD/v2/keys/; do
-  echo "waiting for etcd"
-  sleep 1
-done
-
-# put the flannel config in etcd
-echo "creating flanneld config in etcd"
-curl -sf -L $FLANNEL_ETCD/v2/keys/coreos.com/network/config \
-  -X PUT \
-  --data-urlencode value@/etc/sysconfig/flannel-network.json
-

kubecluster.yaml

@@ -195,11 +195,17 @@ resources:
       group: ungrouped
       config: {get_file: fragments/configure-kubernetes-master.sh}
 
-  configure_flannel:
+  write_flannel_config:
     type: "OS::Heat::SoftwareConfig"
     properties:
       group: ungrouped
-      config: {get_file: fragments/configure-flannel.sh}
+      config: {get_file: fragments/write-flannel-config.sh}
+
+  flannel_config_service:
+    type: "OS::Heat::SoftwareConfig"
+    properties:
+      group: ungrouped
+      config: {get_file: fragments/flannel-config.service.yaml}
 
   enable_services:
     type: "OS::Heat::SoftwareConfig"
@@ -240,7 +246,8 @@ resources:
         - config: {get_resource: kube_user}
         - config: {get_resource: configure_kubernetes}
         - config: {get_resource: enable_services}
-        - config: {get_resource: configure_flannel}
+        - config: {get_resource: write_flannel_config}
+        - config: {get_resource: flannel_config_service}
         - config: {get_resource: kube_examples}
         - config: {get_resource: cfn_signal}