I am trying to migrate a set of microservices from Docker Swarm, to AWS ECS using Fargate.
I have created an ECS cluster. Moreover, I have initialized repositories using the ECR, each of which contains an image of a microservice.
I have successfully came up with a way to create new images, and push them into the ECR. In fact, with each change in the code, a new docker image is built, tagged, and pushed.
Moreover, I have created a task definition that is linked to a service. This task definition contains one container, and all the necessary information. Moreover, its service defines that the task will run in a VPC, and is linked to a load balancer, and has a target group. I am assuming that every new deployment uses the image with the "latest" tag.
So far with what I have explained, everything is clear and is working well.
Below is the part that is confusing me. After every new build, I would like to update the service in order for new tasks with the update image get deployed. I am using the cli to do so with the following command:
aws ecs update-service --cluster <cluster-name> --service <service-name>
Typically, after performing the command, I am monitoring the deployment logs, under the event tab, and checking the state of the service using the following command:
aws ecs describe-services --cluster <cluster-name> --service <service-name>
Finally, I tried to simulate a case where the newly created image contains a bad code. Thus, the new tasks will not be able to get deployed. What I have witnessed is that Fargate will keep trying (without stopping) to deploy the new tasks. Moreover, aside the event logs, the describe-services command does not contain relevant information, other than what Fargate is doing (e.g., registering/deregistering tasks). I am surprised that I could not find any mechanism that instructs Fargate, or the service to stop the deployment and rollback to the already existing one.
I found this article (https://aws.amazon.com/blogs/compute/automating-rollback-of-failed-amazon-ecs-deployments/ ), which provides a solution. However, it is a fairly complicated one, and assumes that each new deployment is triggered by a new task definition, which is not what I want.
Therefore, considering what I have described above, I hope you can answer the following questions:
1) Using CLI commands (For automation purposes) Is there a way to instruct Fargate to automatically stop the current deployment, after failing to deploy new tasks after a few tries?
2) Using the CLI commands, is there a way to monitor the current status of the deployment? For instance, when performing a service update on a service on Docker swarm, the terminal generates live logs on the update process
3) After a failed deployment, is there a way for Fargate to signal an error code, or flag, or message?
