Merge ~kajiya/+git/next-demo:reducing-times into ~kajiya/+git/next-demo:main

[Chloé Smith]

Reduce the time the demo runs for

* Refactor to make the deletion a separate function
* Push the above function into the background after it's run
* Remove `ros`-* installation from the startup-script (no ESM updates yet)
* Use the latest focal image instead so there's less non-ESM updates

[Ankush Pathak (ankushpathak)]

review: Approve

diff --git a/main.sh b/main.sh
index cbf41e4..4557f81 100755
--- a/main.sh
+++ b/main.sh
@@ -1,8 +1,7 @@
 #!/bin/bash
 
-INSTANCE_NAME=focal-$(petname)
 ZONE="us-central1-a"
-IMAGE_NAME="ubuntu-2004-focal-v20231130"
+IMAGE_FAMILY="ubuntu-2004-lts"
 PROJECT="${1}"
 
 lets_spin(){
@@ -36,10 +35,12 @@ wait_instance_connectable() {
 
 launch_instance(){
 
+  INSTANCE_NAME=focal-$(petname)
+
   printf "Launching a new instance...\n"
-  gcloud compute instances create ${INSTANCE_NAME} --machine-type n2d-standard-8 --project ${PROJECT} --image ${IMAGE_NAME} --image-project=ubuntu-os-cloud --zone ${ZONE}   --metadata=startup-script='#! /bin/bash
+  gcloud compute instances create ${INSTANCE_NAME} --machine-type n2d-standard-8 --project ${PROJECT} --image-family ${IMAGE_FAMILY} --image-project=ubuntu-os-cloud --zone ${ZONE} --quiet --metadata=startup-script='#! /bin/bash
   apt update
-  apt -y install mongodb ros-base-python-dev ubuntu-advantage-tools slurm*
+  apt -y install mongodb ubuntu-advantage-tools slurm*
   EOF' & lets_spin
 
   echo "Waiting for instance to start..."
@@ -59,6 +60,12 @@ launch_instance(){
 
 }
 
+delete_instance(){
+  INSTANCE_NAME="${1}"
+  gcloud compute instances delete ${INSTANCE_NAME} --project ${PROJECT} --zone ${ZONE} --quiet
+
+}
+
 while true; do
   clear
   printf "Press any key to begin."
@@ -70,5 +77,6 @@ while true; do
   fi
 
   echo "Deleting the instance and starting over again!"
-  gcloud compute instances delete ${INSTANCE_NAME} --project ${PROJECT} --zone ${ZONE} --quiet & lets_spin
+  delete_instance $INSTANCE_NAME &
+
 done