How to start a GCE instance before SSH connection?

Question

How to ensure that a GCE instance is RUNNING before connecting it?

Because this only works when the instance status is already RUNNING :

gcloud compute ssh --zone $ZONE --project $PROJECT $INSTANCE_NAME

Answer 1

There seem to be three different instance statuses: RUNNING , STOPPING and TERMINATED .
-- permits passing SSH parameters, alike -o ConnectTimeout=60 -o ConnectionAttempts=3 .

#!/bin/bash
PROJECT=$1
ZONE=$2
INSTANCE_NAME=$3
SSH_DEBUG=false
IAP_TUNNEL=false
TROUBLESHOOT=false
TIMEOUT=60
ATTEMPTS=3

if [ $# != 3 ]; then
    echo "Usage: gcloud_ssh.sh PROJECT ZONE INSTANCE_NAME"
    exit 1
else
    declare -a PARAM
    PARAM=(--project "$PROJECT" --zone "$ZONE" "$INSTANCE_NAME")
fi

function getInstanceStatus() {
    gcloud compute instances describe "${PARAM[@]}" --format="get(status)"
}

function whileStopping() {
    echo "GCE instance \`$INSTANCE_NAME\` is shutting down."
    STATUS=$(getInstanceStatus)
}

function startInstance() {
    echo "GCE instance \`$INSTANCE_NAME\` will be brought up."
    gcloud compute instances start "${PARAM[@]}"
    STATUS=$(getInstanceStatus)
}

STATUS=$(getInstanceStatus)

# Loop while the instance status is `STOPPING`.
while [[ "$STATUS" = "STOPPING" ]]; do whileStopping; done

# Start instance, once the instance status is `TERMINATED`.
if [[ "$STATUS" = "TERMINATED" ]]; then startInstance; fi

# This `if` statement might never be the case.
if [[ "$STATUS" != "RUNNING" ]]; then exit 1; fi

# Open SSH, when the instance status is `RUNNING`.
if [[ $IAP_TUNNEL = true ]]; then PARAM=("${PARAM[@]}" --tunnel-through-iap); fi
if [[ $TROUBLESHOOT = true ]]; then PARAM=("${PARAM[@]}" --troubleshoot); fi
PARAM=("${PARAM[@]}" -- -o ConnectTimeout="$TIMEOUT" -o ConnectionAttempts="$ATTEMPTS")
if [[ $SSH_DEBUG = true ]]; then PARAM=("${PARAM[@]}" -v); fi
gcloud compute ssh "${PARAM[@]}"

Then one can define instances as alias shortcuts in file ~/.bash_aliases :

alias ssh_xyz='/home/scripts/gcloud_ssh.sh project-name zone-name instance-name'

---

This script needs role compute.instanceAdmin.v1 and has options SSH_DEBUG , IAP_TUNNEL , TROUBLESHOOT . And for shutting down the remote instance, that would be: sudo poweroff .