Service Mesh Manager (SMM) provides safe upgrades both for the Istio control plane and the Service Mesh Manager dashboard.
Istio follows a rolling support cycle: only the last few versions are supported by the Istio community. The Cisco Istio Distribution included in Service Mesh Manager follows the same model.
Service Mesh Manager follows semantic versioning. To support a new Istio version, a new minor version is created (for example, Istio 1.11 was introduced in Service Mesh Manager 1.8, Istio 1.12 was introduced in Service Mesh Manager 1.9). Always consult the What’s new page to see if a new version of Istio has been introduced.
Overview of the upgrade procedure
The upgrade procedure consists of two steps.
Upgrading the Service Mesh Manager control plane. This is needed regardless of the target Istio version. This step ensures that all Service Mesh Manager components are containing the latest features and security fixes.
This upgrade also upgrades Istio to the latest patch level. For example: if before the upgrade the cluster had Istio 1.11.0, and the target Service Mesh Manager version contains Istio 1.11.2, then this step upgrades Istio to 1.11.2.
For details on performing this step, see Upgrading SMM.
If the new version of Service Mesh Manager contains a new minor or major version of Istio (for example, you have Istio 1.11.2 installed, and the new version contains Istio 1.12), complete the Canary control plane upgrades procedure after upgrading Service Mesh Manager.
Service Mesh Manager avoids big changes to the production traffic by running two versions of the Istio control planes in parallel (for example, 1.11.2 and 1.12.0) on the same cluster. After the upgrade, the existing workloads continue using the older version of Istio (for example, 1.11.2). You can gradually (on a per-namespace basis) move workloads to the new (in the example the 1.12.0) version. This allows operators to start moving services with less business value or risk associated to the new Istio version before moving on to more mission critical services.