client_init.sh

#!/bin/sh -ex

# Load main settings
cat /default_config/settings.sh
. /default_config/settings.sh
cat /config/settings.sh
. /config/settings.sh

# in re-entry we need to remove the vxlan
# on first entry set a routing rule to the k8s DNS server
if ip addr|grep -q vxlan0; then
  ip link del vxlan0
else
  K8S_GW_IP=$(/sbin/ip route | awk '/default/ { print $3 }')
  for local_cidr in ${NOT_ROUTED_TO_GATEWAY_CIDRS}; do
    # command might fail if rule already set
    ip route add ${local_cidr} via ${K8S_GW_IP} || /bin/true
  done
fi

# Delete default GW to prevent outgoing traffic to leave this docker
echo "Deleting existing default GWs"
ip route del 0/0 || /bin/true

# After this point nothing should be reachable -> check
if ping -c 1 -W 1000 8.8.8.8; then
  echo "WE SHOULD NOT BE ABLE TO PING -> EXIT"
  exit 255
fi

# For debugging reasons print some info
ip addr
ip route

# Derived settings
K8S_DNS_IP="$(echo ${K8S_DNS_IPS} | cut -d ' ' -f 1)"
GATEWAY_IP="$(dig +short ${GATEWAY_NAME} @${K8S_DNS_IP})"
#GW_ORG=$(route |awk '$1=="default"{print $2}')
NAT_ENTRY="$(grep $(hostname) /config/nat.conf||true)"

# For debugging reasons print some info
ip addr
ip route

# Check we can connect to the GATEWAY IP
ping -c1 $GATEWAY_IP

# Create tunnel NIC
ip link add vxlan0 type vxlan id $VXLAN_ID dev eth0 dstport 0 || true
bridge fdb append to 00:00:00:00:00:00 dst $GATEWAY_IP dev vxlan0
ip link set up dev vxlan0

# Generate dhclient.conf
echo "backoff-cutoff 2;
initial-interval 1;
link-timeout 10;
reboot 0;
retry 10;
select-timeout 0;
timeout 30;

interface \"vxlan0\"
 {
  request subnet-mask,
          broadcast-address,
          routers,
          #domain-name-servers;
  require routers,
          subnet-mask,
          #domain-name-servers;
 }
" > /etc/dhclient.conf

#Configure IP and default GW though the gateway docker
if [ -z "$NAT_ENTRY" ]; then
  echo "Get dynamic IP"
  dhclient -v -cf /etc/dhclient.conf vxlan0
else
  IP=$(echo $NAT_ENTRY|cut -d' ' -f2)
  VXLAN_IP="${VXLAN_IP_NETWORK}.${IP}"
  echo "Use fixed IP $VXLAN_IP"
  ip addr add $VXLAN_IP/24 dev vxlan0
  route add default gw $VXLAN_GATEWAY_IP
  #echo "nameserver $VXLAN_GATEWAY_IP">/etc/resolv.conf.dhclient
fi

# For debugging reasons print some info
ip addr
ip route

# Check we can connect to the gateway ussing the vxlan device
ping -c1 $VXLAN_GATEWAY_IP

echo "Gateway ready and reachable"