Use a DaemonSet instead of a Deployment to deploy our app

- For high availability reasons, we would like our app to scale linearly
  with the size of the control plane. Using a DaemonSet allows us to run
  one pod on each node-role.kubernetes.io/master node.
- The hope is that the Service that we create should load balance
  between these pods appropriately.

test/integration/app_availability_test.go

@@ -11,27 +11,23 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/require"
-	appsv1 "k8s.io/api/apps/v1"
-	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
 	"github.com/suzerain-io/placeholder-name/test/library"
 )
 
-func TestGetDeployment(t *testing.T) {
+func TestAppAvailability(t *testing.T) {
 	library.SkipUnlessIntegration(t)
 	namespaceName := library.Getenv(t, "PLACEHOLDER_NAME_NAMESPACE")
-	deploymentName := library.Getenv(t, "PLACEHOLDER_NAME_DEPLOYMENT")
+	daemonSetName := library.Getenv(t, "PLACEHOLDER_NAME_APP_NAME")
 
 	client := library.NewClientset(t)
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	appDeployment, err := client.AppsV1().Deployments(namespaceName).Get(ctx, deploymentName, metav1.GetOptions{})
+	daemonSet, err := client.AppsV1().DaemonSets(namespaceName).Get(ctx, daemonSetName, metav1.GetOptions{})
 	require.NoError(t, err)
 
-	cond := library.GetDeploymentCondition(appDeployment.Status, appsv1.DeploymentAvailable)
-	require.NotNil(t, cond)
-	require.Equalf(t, corev1.ConditionTrue, cond.Status, "app should be available: %s", library.Sdump(appDeployment))
+	require.GreaterOrEqual(t, daemonSet.Status.NumberAvailable, int32(1))
 }

test/library/deployment.go

@@ -1,20 +0,0 @@
-/*
-Copyright 2020 VMware, Inc.
-SPDX-License-Identifier: Apache-2.0
-*/
-
-package library
-
-import appsv1 "k8s.io/api/apps/v1"
-
-// GetDeploymentCondition returns the condition with the provided type.
-// Copied from k8s.io/kubectl/pkg/util/deployment/deployment.go to prevent us from vendoring the world.
-func GetDeploymentCondition(status appsv1.DeploymentStatus, condType appsv1.DeploymentConditionType) *appsv1.DeploymentCondition {
-	for i := range status.Conditions {
-		c := status.Conditions[i]
-		if c.Type == condType {
-			return &c
-		}
-	}
-	return nil
-}