Spawning multiple agents with Jenkins ECS plugin (Waiting for next available executor)

Question

I try to configure Jenkins to spawn a slave container on ECS for each build. To achieve this Im using a Amazon EC2 Container Service Plugin.

I defined a cloud and ECS Slave template with a label "ecs". When building a single job, everything works nicely - the slave container is started on a cluster. However, if I try to build another job in parallel, it prints "Waiting for next available executor on ecs" and starts running only after previous job is finished (it's container gets stopped).

I dont understand what's the point of this plugin if only one job can be run at once - I thought it was created to provide elastic creation of slave nodes, appropriate to the workload. Am I missing something?

Answer 1

Consider resources allocation by each running build. If your cluster hasn't enough resources to start more than 1 build in parallel, you can try to scale up the ECS cluster. Be aware that scaling isn't the plugin's task. To add more, you can configure the CPU and memory reservation in the settings of ECS plugin.