Custom VM requirements

[dann1]

Custom VM requirements implemented using oneflow vm_template_contents parameter in a merge_template option passed to the service_template create API Call.

{
  "SERVERLESS_RUNTIME": {
    "NAME": "Function_d5088846-fdb8-4ca8-a0b9-730464d61c75",
    "ID": 320,
    "FAAS": {
      "MEMORY": 133,
      "CPU": 0.33,
      "VCPU": 3,
      "DISK_SIZE": 1337,
      "FLAVOUR": "Function",
      "VM_ID": 231,
      "STATE": "ACTIVE",
      "ENDPOINT": "172.16.100.2"
    },
    "SCHEDULING": {
    },
    "DEVICE_INFO": {
    },
    "SERVICE_ID": 319
  }
}

Also added

• VCPU support. Schema has been updated.
• live resize support for VCPU and MEMORY using BALLOONING
  • if VCPU and MEMORY are specified within the Function VM requirements on the Serverless Runtime specification. Then the upper limit for resizing will be 2x. This multiplier is configurable on /etc/provision-engine/engine.conf within the :capacity section.
  • If no specification is provided, then a baseline VCPU and MEMORY are used as reference alongside the multipliers. These baselines are also configurable on the :capacity section.

# When custom VM requirements for a given function are not specified
# these values will be used to calculate the max resize values for VCPU and MEMORY
# upper limit = default * max 
:capacity:
  :max:
    :vcpu_mult: 2
    :memory_mult: 2
  :default:
    :vcpu: 2
    :memory: 1024

Live resize is needed in order to avoid downtime in case of a future update call issued to the serverless runtime instance where more resources are requested.

Closes #10