I am using Amazon Web Services EC2 Container Service with an Application Load Balancer for my app. When I deploy a new version, I get 503 Service Temporarily Unavailable for about 2 minutes. It is a bit more than the startup time of my application. This means that I cannot do a zero-downtime deployment now.
Is there a setting to not use the new tasks while they are starting up? Or what am I missing here?
UPDATE:
The health check numbers for the target group of the ALB are the following:
Healthy threshold: 5
Unhealthy threshold: 2
Timeout: 5 seconds
Interval: 30 seconds
Success codes: 200 OK
Healthy threshold is 'The number of consecutive health checks successes required before considering an unhealthy target healthy'
Unhealthy threshold is 'The number of consecutive health check failures required before considering a target unhealthy.'
Timeout is 'The amount of time, in seconds, during which no response means a failed health check.'
Interval is 'The approximate amount of time between health checks of an individual target'
UPDATE 2: So, my cluster consists of two EC2 instances, but can scale up if needed. The desired and minimum count is 2. I run one task per instance, because my app needs a specific port number. Before I deploy (jenkins runs an aws cli script) I set the number of instances to 4. Without this, AWS cannot deploy my new tasks (this is another issue to solve). Networking mode is bridge.