daemonset that creates static routes on worker nodes in bluemix kubernetes

Author: Jeffrey Kwong

Dockerfile

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+FROM alpine:latest
+
+WORKDIR /root
+
+RUN apk add --no-cache openssh-client bash git bc jq && \
+      git clone https://github.com/JoeKuan/Network-Interfaces-Script.git && \
+      apk del --no-cache git
+
+ADD add-static-route.sh /root
+RUN chmod a+x /root/add-static-route.sh
+
+CMD [ "/root/add-static-route.sh" ]

add-static-route.sh

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+#!/bin/bash
+
+# create my ssh key
+if [ ! -f /root/ssh-key ]; then
+    ssh-keygen -t rsa -N '' -f /root/ssh-key
+fi
+
+# add it to authorized_keys
+cat /root/ssh-key.pub >> /host/root/.ssh/authorized_keys
+
+# discover my host IP
+myHostIP=`awk -f /root/Network-Interfaces-Script/readInterfaces.awk /host/interfaces device=eth0 | awk '{print $1;}'`
+echo "i am running on ${myHostIP}"
+
+myNetmask=`awk -f /root/Network-Interfaces-Script/readInterfaces.awk /host/interfaces device=eth0 | awk '{print $2;}'`
+
+# reset host fingerprint
+if [ -f /root/.ssh/known_hosts ]; then
+    ssh-keygen -R ${myHostIP}
+fi
+
+mkdir -p /root/.ssh
+touch /root/.ssh/known_hosts
+ssh-keyscan -t rsa ${myHostIP} 1>> /root/.ssh/known_hosts
+
+# get my gateway, which is my network address + 1
+myNetworkAddr=`ipcalc -n ${myHostIP} ${myNetmask} | cut -d= -f2`
+
+#convert to an int
+_oct1=`echo ${myNetworkAddr} | cut -d. -f1 | xargs -I{} echo "{} * 256 * 256 * 256" | bc`
+_oct2=`echo ${myNetworkAddr} | cut -d. -f2 | xargs -I{} echo "{} * 256 * 256" | bc`
+_oct3=`echo ${myNetworkAddr} | cut -d. -f3 | xargs -I{} echo "{} * 256" | bc`
+_oct4=`echo ${myNetworkAddr} | cut -d. -f4 | xargs -I{} echo "{}" | bc`
+_gatewayOct=`echo "${_oct1} + ${_oct2} + ${_oct3} + ${_oct4} + 1" | bc`
+
+_oct1=`echo ${_gatewayOct} | xargs -I{} echo "{} / 256 / 256 / 256 % 256" | bc`
+_oct2=`echo ${_gatewayOct} | xargs -I{} echo "{} / 256 / 256 % 256" | bc`
+_oct3=`echo ${_gatewayOct} | xargs -I{} echo "{} / 256 % 256" | bc`
+_oct4=`echo ${_gatewayOct} | xargs -I{} echo "{} % 256" | bc`
+_gatewayAddr=`echo "${_oct1}.${_oct2}.${_oct3}.${_oct4}"`
+
+myRoutes=`cat /var/run/configmaps/static-routes/static-routes.json | jq '.routes | join (" ")' | sed -e 's/\"//g'`
+
+while [ 1 -eq 1 ]; do
+    # SSH to it and add my routes
+    for _route in ${myRoutes}; do
+        echo "Adding route ${_route} via ${_gatewayAddr}"
+        ssh -i /root/ssh-key root@${myHostIP} "ip route add ${_route} via ${_gatewayAddr}"
+    done
+    sleep 30
+done

kubernetes/add-static-route-daemonset.yaml

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+apiVersion: extensions/v1beta1
+kind: DaemonSet 
+metadata:
+  name: add-static-route
+  labels: 
+    app: test
+spec:
+  template:
+    metadata:
+      labels:
+        app: test
+    spec:
+      containers:
+        - name: add-static-route
+          image: jkwong/add-static-route
+          volumeMounts:
+            - mountPath: "/host/root"
+              name: host-root
+              readOnly: false
+            - mountPath: "/host/interfaces"
+              name: host-interfaces
+              readOnly: false
+            - mountPath: "/var/run/configmaps/static-routes"
+              name: static-routes
+              readOnly: true
+      volumes:
+        - name: host-root
+          hostPath:
+              path: /root
+        - name: host-interfaces
+          hostPath:
+              path: /etc/network/interfaces
+        - name: static-routes
+          configMap:
+              name: static-routes
+              items:
+              - key: static-route.file
+                path: static-routes.json

kubernetes/static-routes-configmap.yaml

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+kind: ConfigMap
+apiVersion: v1
+metadata:
+  creationTimestamp: 2016-02-18T19:14:38Z
+  name: static-routes
+  namespace: default
+data:
+  static-route.file: |-
+    {
+        "routes": [
+            "192.168.0.0/24",
+            "192.168.1.0/24"
+        ]
+    }