Pin version of LXD to latest LTS, and pin juju 2.8.11

Change-Id: I31f5540e0d8991006e8b3767a94fe4126945cafb
Signed-off-by: David Garcia <david.garcia@canonical.com>

installers/charmed_install.sh

@@ -15,7 +15,9 @@
 
 # set -eux
 
-JUJU_AGENT_VERSION=2.8.8
+LXD_VERSION=4.0
+JUJU_VERSION=2.8
+JUJU_AGENT_VERSION=2.8.11
 K8S_CLOUD_NAME="k8s-cloud"
 KUBECTL="microk8s.kubectl"
 MICROK8S_VERSION=1.19
@@ -69,7 +71,7 @@ function install_snaps(){
         export KUBECONFIG=${KUBECFG}
         KUBEGRP=$(id -g -n)
     fi
-    sudo snap install juju --classic --channel=2.8/stable
+    sudo snap install juju --classic --channel=$JUJU_VERSION/stable
 }
 
 function bootstrap_k8s_lxd(){
@@ -149,7 +151,7 @@ EOF
         sudo sysctl --system
         # Install LXD snap
         sudo apt-get remove --purge -y liblxc1 lxc-common lxcfs lxd lxd-client
-        sudo snap install lxd
+        sudo snap install lxd --channel $LXD_VERSION/stable
         # Configure LXD
         sudo usermod -a -G lxd `whoami`
         cat /usr/share/osm-devops/installers/lxd-preseed.conf | sed 's/^config: {}/config:\n  core.https_address: '$LXDENDPOINT':8443/' | sg lxd -c "lxd init --preseed"

installers/full_install_osm.sh

@@ -293,7 +293,7 @@ function install_lxd() {
 
     # Install LXD snap
     sudo apt-get remove --purge -y liblxc1 lxc-common lxcfs lxd lxd-client
-    sudo snap install lxd
+    sudo snap install lxd --channel $LXD_VERSION/stable
 
     # Configure LXD
     sudo usermod -a -G lxd `whoami`
@@ -447,7 +447,7 @@ function install_docker_compose() {
 
 function install_juju() {
     echo "Installing juju"
-    sudo snap install juju --classic --channel=2.8/stable
+    sudo snap install juju --classic --channel=$JUJU_VERSION/stable
     [[ ":$PATH": != *":/snap/bin:"* ]] && PATH="/snap/bin:${PATH}"
     update_juju_images
     echo "Finished installation of juju"
@@ -1575,6 +1575,8 @@ function parse_docker_registry_url() {
     DOCKER_REGISTRY_URL=$(echo "$DOCKER_REGISTRY_URL" | awk '{split($1,a,"@"); print a[2]}')
 }
 
+LXD_VERSION=4.0
+JUJU_VERSION=2.8
 JUJU_AGENT_VERSION=2.8.8
 UNINSTALL=""
 DEVELOP=""