Update to v2beta2 API for HPA

[qui]

The behavior field for HPA, which allows you to specify limits on scaling down, is in the v2beta2 API. This PR just updates the current code to use that API. I'll follow up with a separate PR to add the limits.

Here are the API docs I used: https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.19/#horizontalpodautoscaler-v2beta2-autoscaling

I think I've tested this for all the possible HPA branches with setup_kubernetes_job on kubestage, which means the objects are valid, but it would still be good to check that the new API requests seem equivalent to the old ones. Here are the autoscaling sections I tested:

  autoscaling:
    decision_policy: proportional
    metrics_provider: http
    setpoint: 0.4

  autoscaling:
    decision_policy: proportional
    metrics_provider: http
    setpoint: 0.4
    forecast_policy: moving_average

  autoscaling:
    metrics_provider: mesos_cpu

  horizontal_autoscaling:
    min_replicas: 3
    max_replicas: 15
    uwsgi:
      target_average_value: 0.5
      dimensions:
          service: blah

  horizontal_autoscaling:
    min_replicas: 3
    max_replicas: 15
    uwsgi:
      target_average_value: 0.5

  horizontal_autoscaling:
    min_replicas: 3
    max_replicas: 15
    cpu:
      target_average_value: 0.5

  horizontal_autoscaling:
    min_replicas: 3
    max_replicas: 15
    test-metric:
      target_value: 1
      signalflow_metrics_query: "const(value=1).publish()"

Also note this will cause a big bounce. Here's the config diff:

--- before	2020-11-06 16:33:36.570583229 -0800
+++ after	2020-11-06 16:37:27.717282484 -0800
@@ -8,12 +8,11 @@
               'finalizers': None,
               'generate_name': None,
               'generation': None,
-              'initializers': None,
-              'labels': {'paasta.yelp.com/config_sha': 'config3836dd19',
+              'labels': {'paasta.yelp.com/config_sha': 'config33f02c03',
                          'paasta.yelp.com/git_sha': 'abcdef',
                          'paasta.yelp.com/instance': 'instance',
                          'paasta.yelp.com/service': 'service',
-                         'yelp.com/paasta_config_sha': 'config3836dd19',
+                         'yelp.com/paasta_config_sha': 'config33f02c03',
                          'yelp.com/paasta_git_sha': 'abcdef',
                          'yelp.com/paasta_instance': 'instance',
                          'yelp.com/paasta_service': 'service'},
@@ -45,12 +44,11 @@
                                     'finalizers': None,
                                     'generate_name': None,
                                     'generation': None,
-                                    'initializers': None,
-                                    'labels': {'paasta.yelp.com/config_sha': 'config3836dd19',
+                                    'labels': {'paasta.yelp.com/config_sha': 'config33f02c03',
                                                'paasta.yelp.com/git_sha': 'abcdef',
                                                'paasta.yelp.com/instance': 'instance',
                                                'paasta.yelp.com/service': 'service',
-                                               'yelp.com/paasta_config_sha': 'config3836dd19',
+                                               'yelp.com/paasta_config_sha': 'config33f02c03',
                                                'yelp.com/paasta_git_sha': 'abcdef',
                                                'yelp.com/paasta_instance': 'instance',
                                                'yelp.com/paasta_service': 'service'},
@@ -145,6 +143,7 @@
                                                                            'ephemeral-storage': '1024Mi',
                                                                            'memory': '4096Mi'}},
                                                 'security_context': None,
+                                                'startup_probe': None,
                                                 'stdin': None,
                                                 'stdin_once': None,
                                                 'termination_message_path': None,
@@ -156,6 +155,7 @@
                                 'dns_config': None,
                                 'dns_policy': None,
                                 'enable_service_links': None,
+                                'ephemeral_containers': None,
                                 'host_aliases': None,
                                 'host_ipc': None,
                                 'host_network': None,
@@ -165,6 +165,8 @@
                                 'init_containers': None,
                                 'node_name': None,
                                 'node_selector': {'yelp.com/pool': 'default'},
+                                'overhead': None,
+                                'preemption_policy': None,
                                 'priority': None,
                                 'priority_class_name': None,
                                 'readiness_gates': None,
@@ -178,5 +180,6 @@
                                 'subdomain': None,
                                 'termination_grace_period_seconds': None,
                                 'tolerations': None,
+                                'topology_spread_constraints': None,
                                 'volumes': []}}},
  'status': None}

[stug]

I am pretty sure this looks right, but I found that I was going a little cross-eyed trying to keep everything straight in my head.

[stug]

That issue looks like it's still open, but it sounds like you actually created HPAs on kubestage so I am assuming this is ok.

[qui]

Yeah, the issue is only in the v2beta1 client spec I think. I am also assuming creating HPAs on kubestage proves that this issue is no longer relevant with the new API.