Jenkins pipeline - check if an ECS service exist - amazon-web-services

Question

I'm using AWS ECS CLI within Jenkins pipeline to automate my CICD. What I'm trying to do is I want to create a service based upon the task definition if the service does not exist yet, if the service already exists I just want to update it instead. Here is the create-service cli command:
aws ecs create-service \
--cluster $stg_cluster \
--task-definition $task_def \
--service-name $ecs_service \
--desired-count 1 \
--launch-type EC2 \
--scheduling-strategy REPLICA \
--load-balancers \"targetGroupArn=$target_group_arn,containerName=$container_name,containerPort=80\" \
--deployment-configuration \"maximumPercent=200,minimumHealthyPercent=100\"
It works fine for the first time but will fail at subsequent deployments because of this error:
An error occurred (InvalidParameterException) when calling the CreateService operation: Creation of service was not idempotent.
I believe I have to use the command update-service instead but not sure how to write ECS CLI command to check if an ECS service has already existed. One way I can think of is I can check the returned code from the create-service cli command see if it equals to 0 but again not sure how to retrieve it from the pipeline. Thanks for your help.

Answer 1

First you can run aws ecs describe-services to check if that service is already there and the state is ACTIVE. If it's active then you can run aws ecs update-service to update existing service. If it's not ACTIVE then you can run aws ecs create-service to create the service.
This is a sample code you can use to check if a service is already created and active:
aws ecs describe-services --cluster CLUSTER_NAME --services SERVIVE_NAME | jq --raw-output 'select(.services[].status != null ) | .services[].status'
and then use an if condition to run update-service or create-service.

Answer 2

This is my code in case anyone is interested.
#Jenkinsfile pipeline
stage('Deploy')
{
steps {
....
script {
int count = sh(script: """
aws ecs describe-services --cluster $ecs_cluster --services $ecs_service | jq '.services | length'
""",
returnStdout: true).trim()
echo "service count: $count"
if (count > 0) {
//ECS service exists: update
echo "Updating ECS service $ecs_service..."
sh(script: """
aws ecs update-service \
--cluster $ecs_cluster \
--service $ecs_service \
--task-definition $task_def \
""")
}
else {
//ECS service does not exist: create new
echo "Creating new ECS service $ecs_service..."
sh(script: """
aws ecs create-service \
--cluster $ecs_cluster \
--task-definition $task_def \
--service-name $ecs_service \
--desired-count 1 \
--launch-type EC2 \
--scheduling-strategy REPLICA \
--load-balancers \"targetGroupArn=${target_group_arn},containerName=$app_name,containerPort=80\" \
--deployment-configuration \"maximumPercent=200,minimumHealthyPercent=100\"
""")
}
}
}
}

Answer 3

Use query parameter in aws cli :
#!/bin/bash
CLUSTER="test-cluster-name"
SERVICE="test-service-name"
echo "check ECS service exists"
status=$(aws ecs describe-services --cluster ${CLUSTER} --services ${SERVICE} --query 'failures[0].reason' --output text)
if [[ "${status}" == "MISSING" ]]; then
echo "ecs service ${SERVICE} missing in ${CLUSTER}"
exit 1
fi
same in jenkins pipline:
stage('Deploy')
{
steps {
....
script {
string status = sh(script: """
aws ecs describe-services --cluster $ecs_cluster --services $ecs_service --query 'failures[0].reason' --output text
""",
returnStdout: true).trim()
echo "service status: $status"
if (status == 'MISSING') {
echo "ecs service: $ecs_service does not exists in $ecs_cluster"
// put create service logic
}
}}}