Upgrade and Rollback Strategy

This guide details comprehensive strategies and best practices for upgrading Istio in your environment—from careful planning and execution to effective rollback procedures. We have designed this guide to be both informative and engaging, helping you confidently navigate every step of the process.

Upgrade Planning and Pre-Assessment

Before upgrading Istio, it is essential to perform a thorough assessment of your current deployment to fully understand the potential impact of the changes. To help ensure a smooth transition, we recommend completing the following steps:

1. Review Istio Use Cases

   • Identify key workloads that rely on Istio, including ingress/egress gateways, mutual TLS policies, service-to-service communication, and any custom Envoy filters.
   • Take time to examine your service mesh configurations such as VirtualServices, DestinationRules, Sidecar resources, and AuthorizationPolicies.

2. Evaluate Dependencies and Compatibility

   • Verify integrations with external tools like Prometheus, Grafana, OpenTelemetry, or external authorization systems.
   • Review any deprecated or removed features in your target Istio version to avoid unexpected issues during the upgrade.

3. Backup Istio Configuration

   • Back up your current Istio configuration—including all Custom Resource Definitions (CRDs)—so you can easily roll back if needed.
   • Make sure that workload configurations are safely stored in version control for quick recovery.

4. Test in a Non-Production Environment

   • Deploy the target Istio version in a staging environment that closely mirrors production.
   • Validate that traffic routing, security policies, and telemetry integrations function as expected. This extra step helps ensure a smooth transition and builds confidence in your upgrade process.

Upgrade Strategy

There are two primary approaches for upgrading Istio: Canary Upgrade and In-Place Upgrade. Your choice will depend on your risk tolerance and operational requirements.

Step-by-Step Instructions

For detailed, step-by-step instructions on performing Canary and In-Place upgrades—including rollback procedures—see Upgrade and Rollback Instructions.

Canary Upgrade (Recommended)

A canary upgrade allows you to run the new and existing versions concurrently. This approach lets you migrate workloads gradually while minimizing risk and ensuring that you have a quick rollback option if needed.

• Deploy the new Istio control plane alongside the current version without disrupting existing workloads.
• Incrementally migrate workloads by updating namespace labels to reference the new version.
• Monitor traffic, logs, and service behavior before finalizing the migration. This continuous monitoring helps you catch any issues early.
• If issues occur, simply revert workloads to the previous version without a complete rollback.
• Once all workloads are confirmed to run on the new version, decommission the old control plane with confidence.

In-Place Upgrade

This approach updates the existing Istio version with the new one in a single step. While simpler, it carries a higher risk because all workloads are immediately affected.

• Suitable for environments that require rapid upgrades.
• Involves a brief service interruption during the upgrade.
• Carries a higher risk since every workload is immediately updated.
• Requires a thoroughly tested rollback plan to mitigate potential issues.

Rollback Plan

A robust rollback strategy is essential in case unexpected issues arise. The rollback process will vary depending on the upgrade method you choose:

• Canary Upgrade: Redirect workloads back to the previous control plane with minimal downtime.
• In-Place Upgrade: Roll back by fully uninstalling the new version and reinstalling the previous one. Note that this method may involve some downtime and potential configuration drift.

Best Practices for Rollback:

• Always back up all CRDs and configurations before initiating the upgrade.
• Verify downgrade compatibility, ensuring that any new fields introduced during the upgrade do not cause issues when reverting.
• Use a phased approach during canary upgrades to minimize risks.
• Test the rollback process in a staging environment before applying it in production for extra peace of mind.

Review of Known Issues and Concerns

Before proceeding, it is advisable to review historically reported issues from similar upgrades. Some key concerns include:

• Proxy Failures for External Services: Some configurations that rely on external services have experienced issues after upgrading.
• Changes in ExternalName Service Handling: Modifications in handling ExternalName services may require updates to your configurations.
• TLS and Certificate Handling Adjustments: There have been compatibility issues related to auto-SNI and certificate verification.
• Helm Upgrade Issues on Managed Kubernetes Services: Platforms such as AKS, EKS, and GCP have reported problems during Istio upgrades.

We strongly recommend taking the time to review these known issues in detail and testing potential impacts before proceeding with the upgrade.

By following this structured approach, you can minimize risks and ensure a smooth, confident transition to the new Istio version.