Istio collects a number of metrics automatically by default. Metrics can be added or removed by changing the configuration at any time. Let's take a look:

1. Let's check out attributemanifest, which is a list of attributes for Kubernetes and Istio:

$ kubectl -n istio-system get attributemanifest
NAME           AGE
istioproxy     5d
kubernetes     5d

As we can see, Kubernetes has its own set of manifest attributes. Istio also provides a set of manifest attributes.

2. Check the attribute list for istioproxy and notice the list of predefined matrices:

$ kubectl -n istio-system get attributemanifest istioproxy -o yaml
...
spec:
 attributes:
   check.error_code:
...
    check.error_code:
 valueType: INT64
 check.error_message:
 valueType: STRING
 connection.duration:
      valueType: DURATION
...

Here, we can see various attributes, such as errorcode, error_message, and connection.duration. These attributes are generated and consumed by different services. Istio uses shared attributes that can be used across various components. For example, the authenticated user information that's generated by a certain function can be used by the Envoy proxy to store that information in the logging backend.

Next, we will implement a new metrics collection that can be pushed down to Mixer. Then, Mixer pushes those down to the Envoy proxy level.