Merge pull request k8snetworkplumbingwg#317 from caribbeantiger/ipRec…

…oncileCronConfig

Ip reconcile cron config via ENV

doc/extended-configuration.md

@@ -138,8 +138,12 @@ You'll note that in the `ipam` section there's a lot less parameters than are us
 
 You may want to provide a cron expression to configure how frequently the ip-reconciler runs. This is done via the flatfile.
 
-Look for the following parameter `"reconciler_cron_expression"` located in `script/install-cni.sh` and change to your desired schedule.
-
+You can speficy the `WHEREABOUTS_RECONCILER_CRON` environment variable in your daemonset definition file to override the default cron expression:
+```yaml
+       env:
+        - name: WHEREABOUTS_RECONCILER_CRON
+          value: 30 * * * *
+```
 ## Installing etcd. (optional)
 
 etcd installation is optional. By default, we recommend the custom resource backend (given in the first example configuration).
@@ -156,4 +160,4 @@ kubectl get svc | grep "etcd-cluster-client"
 
 This will give you the service name and the port to use, in this case you'll specify it in the configuration in a `service-name:port` format, the default port for etcd clients is `2379`.
 
-*Note*: It's important to remember that CNI plugins (typically) run directly on the host and not inside pods. This means that if you use the DNS name (which might look something like `example-etcd-cluster-client.default.svc.cluster.local`) for the service (recommended) make sure that you can resolve those hostnames directly from your hosts. You may find some tips regarding that [here](https://blog.heptio.com/configuring-your-linux-host-to-resolve-a-local-kubernetes-clusters-service-urls-a8c7bdb212a7).
+*Note*: It's important to remember that CNI plugins (typically) run directly on the host and not inside pods. This means that if you use the DNS name (which might look something like `example-etcd-cluster-client.default.svc.cluster.local`) for the service (recommended) make sure that you can resolve those hostnames directly from your hosts. You may find some tips regarding that [here](https://blog.heptio.com/configuring-your-linux-host-to-resolve-a-local-kubernetes-clusters-service-urls-a8c7bdb212a7).

script/install-cni.sh

@@ -13,6 +13,7 @@ set -u -e
 CNI_BIN_DIR=${CNI_BIN_DIR:-"/host/opt/cni/bin/"}
 WHEREABOUTS_KUBECONFIG_FILE_HOST=${WHEREABOUTS_KUBECONFIG_FILE_HOST:-"/etc/cni/net.d/whereabouts.d/whereabouts.kubeconfig"}
 CNI_CONF_DIR=${CNI_CONF_DIR:-"/host/etc/cni/net.d"}
+WHEREABOUTS_RECONCILER_CRON=${WHEREABOUTS_RECONCILER_CRON:-30 4 * * *}
 
 # Make a whereabouts.d directory (for our kubeconfig)
 
@@ -103,7 +104,7 @@ EOF
   "kubernetes": {
     "kubeconfig": "${WHEREABOUTS_KUBECONFIG_LITERAL}"
   },
-  "reconciler_cron_expression": "30 4 * * *"
+  "reconciler_cron_expression": "${WHEREABOUTS_RECONCILER_CRON}"
 }
 EOF