Version 1.9

Preparing to migrate from Istio

Migrating from Istio to Anthos Service Mesh takes some planning. This page provides information to help you prepare for the migration.

Reviewing the supported features

The features Anthos Service Mesh supports differ between platforms. Review the Supported features to see which features are available for your platform. Some features are enabled by default, and others you can optionally enable by creating an IstioOperator configuration file.

Preparing configuration files

If you customized the Istio installation, you need the same customizations when you migrate to Anthos Service Mesh. If you customized the installation by adding the --set values flag, add those settings to an IstioOperator YAML file. You specify the file by using the -f flag when you run the istioctl install command. If you are using the Google-provided install_asm script to migrate to Anthos Service Mesh, you can specify the --custom-overlay option with the file.

Choosing a certificate authority

You can continue to use Citadel (now incorporated in istiod) as the certificate authority (CA) for issuing mutual TLS (mTLS) certificates, or you can choose to migrate to Anthos Service Mesh certificate authority (Mesh CA).

We generally recommend that you use Mesh CA for the following reasons:

  • Mesh CA is a highly reliable and scalable service that is optimized for dynamically scaled workloads on Google Cloud.
  • With Mesh CA, Google manages the security and availability of the CA backend.
  • Mesh CA lets you rely on a single root of trust across clusters.

However, there are cases where you might want to consider using Citadel, such as the following:

  • If you have a custom CA.
  • You can't schedule downtime for the migration to Mesh CA. If you choose Citadel, there's little downtime because mTLS traffic isn't interrupted during the migration. If you choose Mesh CA, you need to schedule downtime for the migration because the root of trust changes from Citadel to Mesh CA. To complete the migration to the Mesh CA root of trust, you need to restart all Pods in all namespaces. During this process, the old Pods cannot establish mTLS connections with the new Pods.