Fixes bug 2285: MTU Issue

There is a bug in microk8s 1.26.7 where calico will not be
created with the correct MTU:

https://github.com/canonical/microk8s/issues/4142



This patch adds a workaround.

Change-Id: I164e612c03a70e9417b6f736b71f71b8050fddbc
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>

installers/charmed_install.sh

@@ -76,6 +76,11 @@ function install_snaps(){
         sudo snap install microk8s --classic --channel=${MICROK8S_VERSION}/stable ||
           FATAL_TRACK k8scluster "snap install microk8s ${MICROK8S_VERSION}/stable failed"
         sudo usermod -a -G microk8s `whoami`
+        # Workaround bug in calico MTU detection
+        if [ ${DEFAULT_IF_MTU} -ne 1500 ] ; then
+            sudo mkdir -p /var/lib/calico
+            sudo ln -sf /var/snap/microk8s/current/var/lib/calico/mtu /var/lib/calico/mtu
+        fi
         sudo cat /var/snap/microk8s/current/args/kube-apiserver | grep advertise-address || (
                 echo "--advertise-address $DEFAULT_IP" | sudo tee -a /var/snap/microk8s/current/args/kube-apiserver
                 sg ${KUBEGRP} -c microk8s.stop
@@ -538,6 +543,7 @@ function install_microstack() {
 
 DEFAULT_IF=`ip route list match 0.0.0.0 | awk '{print $5; exit}'`
 DEFAULT_IP=`ip -o -4 a |grep ${DEFAULT_IF}|awk '{split($4,a,"/"); print a[1]; exit}'`
+DEFAULT_IF_MTU=`ip a show ${DEFAULT_IF} | grep mtu | awk '{print $5}'`
 
 check_arguments $@
 mkdir -p ~/.osm