Ensure no downtime during rollouts (#854)

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## Motivation and Context
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The following PR ensures we don't have downtime when we are doing
rollouts during deployment/promotions.

## How Has This Been Tested?
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tested? -->

## Breaking Changes
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## Types of changes
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the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
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that apply. -->
- [ ] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [ ] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
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Signed-off-by: Radoslav Dimitrov <radoslav@stacklok.com>

deploy/pkg/k8s/registry.go

@@ -72,6 +72,13 @@ func DeployMCPRegistry(ctx *pulumi.Context, cluster *providers.ProviderInfo, env
 		},
 		Spec: &v1.DeploymentSpecArgs{
 			Replicas: pulumi.Int(2),
+			Strategy: &v1.DeploymentStrategyArgs{
+				Type: pulumi.String("RollingUpdate"),
+				RollingUpdate: &v1.RollingUpdateDeploymentArgs{
+					MaxUnavailable: pulumi.IntPtr(0), // Never reduce capacity during updates
+					MaxSurge:       pulumi.IntPtr(1), // Create new pods first, then terminate old
+				},
+			},
 			Selector: &metav1.LabelSelectorArgs{
 				MatchLabels: pulumi.StringMap{
 					"app": pulumi.String("mcp-registry"),