How to wait in a bash script until an AWS instance is complete

Question

I am using a bash script to create an AWS instance through the CLI and the cloud information template. I want my script to wait until the instance is created before I go into my script. Right now, I use a while loop to “describe stacks” every 5 seconds and break out of the loop when status = "CREATE_COMPLETE" or some kind of failure status. Does anyone know a more elegant way to do this?

stackStatus="CREATE_IN_PROGRESS" while [[ 1 ]]; do echo "${AWS_CLI_PATH}" cloudformation describe-stacks --region "${CfnStackRegion}" --stack-name "${CfnStackName}" response=$("${AWS_CLI_PATH}" cloudformation describe-stacks --region "${CfnStackRegion}" --stack-name "${CfnStackName}" 2>&1) responseOrig="$response" response=$(echo "$response" | tr '\n' ' ' | tr -s " " | sed -e 's/^ *//' -e 's/ *$//') if [[ "$response" != *"StackStatus"* ]] then echo "Error occurred creating AWS CloudFormation stack. Error:" echo " $responseOrig" exit -1 fi stackStatus=$(echo $response | sed -e 's/^.*"StackStatus"[ ]*:[ ]*"//' -e 's/".*//') echo " StackStatus: $stackStatus" if [[ "$stackStatus" == "ROLLBACK_IN_PROGRESS" ]] || [[ "$stackStatus" == "ROLLBACK_COMPLETE" ]] || [[ "$stackStatus" == "DELETE_IN_PROGRESS" ]] || [[ "$stackStatus" == "DELETE_COMPLETE" ]]; then echo "Error occurred creating AWS CloudFormation stack and returned status code ROLLBACK_IN_PROGRESS. Details:" echo "$responseOrig" exit -1 elif [[ "$stackStatus" == "CREATE_COMPLETE" ]]; then break fi # Sleep for 5 seconds, if stack creation in progress sleep 5 done 

Answer 1

Ec2-wait-instance-exists is similar to what you need: http://docs.aws.amazon.com/cli/latest/reference/ec2/wait/instance-exists.html

Answer 2

The aws cli command provides the wait subcommand for most commands that create resources. For your scenario, you can use the wait subcommand to wait for the stack-create-complete event:

 aws cloudformation wait stack-create-complete --stack-name myStackName 

Answer 3

Here is how I did it. After starting the instance, I wait for the public IP:

 INSTANCE_ID="$(aws ec2 run-instances --cli-input-json "${LAUNCH_SPEC}" | jq -r '.Instances[0].InstanceId')" echo "Instance id ${INSTANCE_ID}" while true; do PUBLIC_IP="$(aws ec2 describe-instances --instance-ids ${INSTANCE_ID} | jq -r '.Reservations[0].Instances[0].PublicIpAddress')" if [[ "${PUBLIC_IP}" =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then break; fi sleep 1 echo -n '.' done 

Defined previously by LAUNCH_SPEC

Answer 4

The following is a general check_status function. Useful for several actions, such as checking if the stack is deployed or if the EKS cluster is working, and if nodes are added to it.

 check_status() { max_tries="$1" test_command="$2" required_value="$3" error="$4" ok="false" for i in 'seq 1 $max_tries'; do return_value=$(eval ${test_command}) if [ "$return_value" == "$required_value" ]; then ok="true" break else echo -n "." fi sleep 5 done if [ "$ok" == "false" ]; then printf "\n\e[31mERROR:\e[0m $error\n" exit 1 fi } check_vpc() { echo "Waiting for stack status..." vpc_stack_status="aws cloudformation describe-stacks --stack- name=${vpc_stack_name} --query 'Stacks[0].StackStatus' --output text" msg="Stack creation failed - giving up" check_status "100" "$vpc_stack_status" "CREATE_COMPLETE" "$msg" [[ $? == "0" ]] && echo "VPC stack deployed successfully" }