istio.io/istio@v0.0.0-20240520182934-d79c90f27776/releasenotes/notes/disable-host-header-fallback.yaml (about)

     1  apiVersion: release-notes/v2
     2  kind: bug-fix
     3  area: telemetry
     4  releaseNotes:
     5  - |
     6    **Updated** Prometheus telemetry behavior for inbound traffic to disable host header fallback by default. This will
     7    prevent traffic coming from out-of-mesh locations from potential polluting the `destination_service` dimension in
     8    metrics with junk data (and exploding metrics cardinality). With this change, it is possible that users relying on
     9    host headers for labeling the destination service for inbound traffic from out-of-mesh workloads will see that traffic
    10    labeled as `unknown`. The behavior can be restored by modifying Istio configuration to remove the `disable_host_header_fallback: true`
    11    configuration.
    12  upgradeNotes:
    13    - title: Host header fallback disabled by default for Prometheus metrics for *all* inbound traffic.
    14      content: |
    15        Host header fallback for determining values for Prometheus `destination_service` labels has been disabled for all incoming traffic.
    16        Previously, this was disabled *only* for traffic arriving at Gateways. If you are relying on host header fallback behavior to properly
    17        label the `destination_service` in Prometheus metrics for traffic originating from out-of-mesh workloads, then you will need to update the telemetry
    18        configuration to enable host header fallback.
    19