Set default CPU limit as 2 and show in TMDEv2/v3/v4 task metadata

[chienhanlin]

Summary

This PR sets default CPU limit from 0 to 2 if Null, zero, and CPU values of 1 is assigned to a container in a task definition.

Cases and the corresponding Task metadata endpoint (TMDE) task response are listed as followed:

• Case 1: CPU limit is Null or 0 or 1 for a container in the task definition -> TMDEv2/v3/v4 task metadata shows the container with CPU limit as 2
• Case 2: CPU limit is >= 2 for a container in the task definition -> TMDEv2/v3/v4 task metadata shows the container with CPU limit defined in the task definition

Reference of CPU limit can be found here

Implementation details

1. Set the minimumCPUUnit and defaultCPU as 2
2. Update container.CPU in ContainerResponse if it is less than minimumCPUUnit
3. Update the expected CPU limit to 2 in TestTaskResponseMarshal

Testing

New tests cover the changes: no

Manual tests

Run a task definition with 5 containers with different CPU limits as follows:

1. Container sleepWithCPUNotSpecified has CPU limit Null
2. Container sleepWithCPU0 has CPU limit 0
3. Container sleepWithCPU1 has CPU limit 1
4. Container sleepWithCPU2 has CPU limit 2
5. Container sleepWithCPU3 has CPU limit 3

All containers have Memory limit 50.

Task metadata from TMDEv3
curl ${ECS_CONTAINER_METADATA_URI}/task

{
   "Cluster":"default",
   "TaskARN":"TaskARN",
   ...
   "Containers":[
      { ..."Name":"sleepWithCPUNotSpecified", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU0", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU1", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU2", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU3", ... "Limits":{ "CPU":3, "Memory":50}, ...},
   ],
  ...
}

Task metadata from TMDEv4
curl ${ECS_CONTAINER_METADATA_URI_V4}/task

{
   "Cluster":"default",
   "TaskARN":"TaskARN",
   "LaunchType":"EC2",
   ...
   "Containers":[
      { ..."Name":"sleepWithCPUNotSpecified", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU0", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU1", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU2", ... "Limits":{ "CPU":2, "Memory":50}, ...},
      { ..."Name":"sleepWithCPU3", ... "Limits":{ "CPU":3, "Memory":50}, ...},
   ],
}

Description for the changelog

Bug - Fixed the number of cpu units the Agent will reserve for the Linux container instances.

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.