[fcos] GCP: add a script and a service which ensure GCP routes are set correctly

templates/common/gcp/files/gcp-routes-sh.yaml

@@ -0,0 +1,96 @@
+filesystem: "root"
+mode: 0744
+path: "/usr/local/bin/gcp-routes.sh"
+contents:
+  inline: |
+    #!/bin/bash
+
+    declare -A routes
+    curler() {
+      curl --silent -L -H "Metadata-Flavor: Google" "http://metadata.google.internal/computeMetadata/v1/instance/${1}"
+    }
+
+    get_ifname() {
+      sysfs_path="/sys/class/net"
+      for dev in $(find ${sysfs_path} -maxdepth 1  -mindepth 1);
+      do
+          local mac=$(<${dev}/address);
+          local name="$(basename ${dev})"
+          if [ "${mac}" == "${1}" ];
+          then
+              echo "${name}"
+              return;
+          fi
+      done
+    }
+
+    set_routes() {
+      local dev="${1}"
+      read -a dev_routes <<< "${routes[$dev]}"
+      for cur_route in $(ip route show dev ${dev} table local proto 66 | awk '{print$2}');
+      do
+          if [[ ! "${dev_routes[@]}" =~ "${cur_route}" ]];
+          then
+              echo "Removing stale forwarded IP ${cur_route}/32"
+              ip route del ${cur_route}/32 dev ${dev} table local proto 66
+          fi
+      done
+      for route in ${dev_routes[@]}
+      do
+          ip route replace to local ${route} dev $dev proto 66
+      done
+      unset dev_routes
+    }
+
+    del_routes() {
+      local dev="${1}"
+      read -a dev_routes <<< "${routes[$dev]}"
+      for cur_route in $(ip route show dev ${dev} table local proto 66 | awk '{print$2}');
+      do
+          if [[ "${dev_routes[@]}" =~ "${cur_route}" ]];
+          then
+              echo "Removing forwarded IP ${cur_route}/32"
+              ip route del ${cur_route}/32 dev ${dev} table local proto 66
+          fi
+      done
+      unset dev_routes
+    }
+
+    run() {
+      net_path="network-interfaces/"
+      for vif in $(curler ${net_path}); do
+          hw_addr=$(curler "${net_path}${vif}mac")
+          fwip_path="${net_path}${vif}forwarded-ips/"
+          dev_name="$(get_ifname ${hw_addr})"
+          for level in $(curler ${fwip_path})
+          do
+              for fwip in $(curler ${fwip_path}${level})
+              do
+                  echo "Processing route for NIC ${vif}${hw_addr} as ${dev_name} for ${fwip}"
+                  routes[$dev_name]+="${fwip} "
+              done
+          done
+          $"${1}" ${dev_name}
+
+          routes[$dev_name]=""
+          unset hw_addr
+          unset fwip_path
+          unset dev_name
+      done
+    }
+
+    case "$1" in
+      start)
+        while :; do
+          run set_routes
+          sleep 30
+        done
+        ;;
+      cleanup)
+        run del_routes
+        ;;
+      *)
+        echo $"Usage: $0 {start|cleanup}"
+        exit 1
+
+    esac

templates/common/gcp/units/gcp-routes-service.yaml

@@ -0,0 +1,19 @@
+name: "gcp-routes.service"
+enabled: true
+contents: |
+  [Unit]
+  Description=Update GCP routes for forwarded IPs.
+  ConditionKernelCommandLine=|ignition.platform.id=gce
+  ConditionKernelCommandLine=|ignition.platform.id=gcp
+  After=network.target
+
+  [Service]
+  Type=simple
+  ExecStart=/bin/bash /usr/local/bin/gcp-routes.sh start
+  ExecStopPost=/bin/bash /usr/local/bin/gcp-routes.sh cleanup
+  User=root
+  RestartSec=30
+  Restart=always
+
+  [Install]
+  WantedBy=multi-user.target