Istio 1.10 Upgrade Notes
Important changes to consider when upgrading to Istio 1.10.0.
When you upgrade from Istio 1.9 to Istio 1.10, you need to consider the changes on this page. These notes detail the changes which purposefully break backwards compatibility with Istio 1.9. The notes also mention changes which preserve backwards compatibility while introducing new behavior. Changes are only included if the new behavior would be unexpected to a user of Istio 1.9.
Inbound Forwarding Configuration
The behavior of inbound forwarding has been modified for Istio 1.10. This change is enabled
by default in Istio 1.10 and it can be disabled by configuring the
variable in Istiod.
Previously, requests would be forwarded to
localhost. This leads to two important differences compared to running applications
- Applications that bind to
localhostwill be exposed to external pods.
- Applications that bind to
<POD_IP>will not be exposed to external pods.
The latter is a common source of friction when adopting Istio, in particular with stateful services where this is common.
The new behavior instead forwards the request as is. This matches the behavior a user would see without Istio installed.
However, as a result, applications that have come to rely on
localhost being exposed externally by Istio may stop working.
To help detect these situations, we have added a check to find pods that will be impacted. You can run the
experimental precheck command to get a report of any pods binding to
localhost on a port exposed in a Service. This command is
available in Istio 1.10+. Without action, these ports will no longer be accessible upon upgrade.
$ istioctl experimental precheck Error [IST0143] (Pod echo-local-849647c5bd-g9wxf.default) Port 443 is exposed in a Service but listens on localhost. It will not be exposed to other pods. Error [IST0143] (Pod echo-local-849647c5bd-g9wxf.default) Port 7070 is exposed in a Service but listens on localhost. It will not be exposed to other pods. Error: Issues found when checking the cluster. Istio may not be safe to install or upgrade. See https://istio.io/latest/docs/reference/config/analysis for more information about causes and resolutions.
Regardless of Istio version, the behavior can be explicitly controlled by the
For example, to configure the 9080 port to explicitly be sent to localhost:
apiVersion: networking.istio.io/v1beta1 kind: Sidecar metadata: name: ratings spec: workloadSelector: labels: app: ratings ingress: - port: number: 9080 protocol: HTTP name: http defaultEndpoint: 127.0.0.1:9080
Sidecar Injector Changes
The logic to determine if a pod requires sidecar injection or not has been updated to make use of
new Kubernetes features. Previously, the webhook was triggered at a coarse grain level, selecting any
pods in a namespace with a matching
This has two limitations:
Opting out individual pods with the
sidecar.istio.io/injectannotation would still trigger the webhook, only to be filtered out by Istio. This can have the unexpected impact of adding a dependency on Istio when one is not expected.
There is no way to opt-in an individual pod, with
sidecar.istio.io/inject, without enabling injection for the entire namespace.
These limitations have both been resolved. As a result, additional pods may be injected that were not in previous versions,
if they exist in a namespace without an
istio-injection label set but have the
sidecar.istio.io/inject annotation set to
true on the pod.
This is expected to be an uncommon case, so for most users there will be no behavioral changes to existing pods.
If this behavior is not desired, it can be temporarily disabled with
This option will be removed in future releases.
See the updated Automatic sidecar injection documentation for more information.
.global stub domain
This change can be temporarily disabled if desired by setting the environment variable
PILOT_ENABLE_LEGACY_AUTO_PASSTHROUGH=true in Istiod. However, this is strongly discouraged, as it negates the fix to ISTIO-SECURITY-2021-006.
Please follow the Multicluster Installation documentation for more information.