The Istio service mesh architecture is comprised of several components, from istiod to Jaeger. Each component must work as expected for the mesh to work well overall. Kiali regularly checks the status of each Istio component to ensure the mesh is healthy.
A component status will be one of:
Not healthy and
Not found status means that Kiali is not able to find the deployment. The
Unreachable status means that Kiali hasn’t been succesfuly able to communicate with the component (Prometheus, Grafana and Jaeger). The
Not healthy status means that the deployment doesn’t have the desired amount of replicas running. The
Healthy status is when the component is not in the previous ones, plus, healthy components won’t be shown in the list.
Regarding the severity of each component, there are only to options:
core components are those shown as errors (in red) whereas the
add-ons are displayed as warnings (in orange).
By default, Kiali checks the following components installed in the control plane namespace: istiod, ingress, egress; and prometheus, grafana and jaeger accessible thought their services.
In some situations, it would be useful to get information about the certificates used by internal mTLS, for example:
Know whether the default CA is used or if there is another CA configured
Check the certificates issuer and their validity timestamps to troubleshoot any issue with certificates
The certificates shown depends on how Istio is configured. The following cases are possible:
The following is an example of viewing the default case:
Note that displaying this configuration requires permissions to read secrets (istio-ca-secret by default, possibly cacerts or any secret configured when using DNS certificates).
Having this permissions may concern users. For this reason, this feature is implemented as a feature flag and not only can be disabled, avoiding any extra permissions to read secrets, but also a list of secrets can be configured to explicitly grant read permissions for some secrets in the control plane namespace. For more information, check the secret permissions section.