Envoy Access Logs

The simplest kind of Istio logging is Envoy’s access logging. Envoy proxies print access information to their standard output. The standard output of Envoy’s containers can then be printed by the kubectl logs command.

Before you begin

• Setup Istio by following the instructions in the Installation guide.

  The egress gateway and access logging will be enabled if you install the demo configuration profile.

• Deploy the curl sample app to use as a test source for sending requests. If you have automatic sidecar injection enabled, run the following command to deploy the sample app:

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  $ kubectl apply -f @samples/curl/curl.yaml@

  Otherwise, manually inject the sidecar before deploying the curl application with the following command:

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  $ kubectl apply -f <(istioctl kube-inject -f @samples/curl/curl.yaml@)

  You can use any pod with curl installed as a test source.

• Set the SOURCE_POD environment variable to the name of your source pod:

  $ export SOURCE_POD=$(kubectl get pod -l app=curl -o jsonpath={.items..metadata.name})

• Start the httpbin sample.

  If you have enabled automatic sidecar injection, deploy the httpbin service:

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  $ kubectl apply -f @samples/httpbin/httpbin.yaml@

  Otherwise, you have to manually inject the sidecar before deploying the httpbin application:

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  $ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@)

Enable Envoy’s access logging

Istio offers a few ways to enable access logs. Use of the Telemetry API is recommended

Using Telemetry API

The Telemetry API can be used to enable or disable access logs:

apiVersion: telemetry.istio.io/v1
kind: Telemetry
metadata:
  name: mesh-default
  namespace: istio-system
spec:
  accessLogging:
    - providers:
      - name: envoy

The above example uses the default envoy access log provider, and we do not configure anything other than default settings.

Similar configuration can also be applied on an individual namespace, or to an individual workload, to control logging at a fine grained level.

For more information about using the Telemetry API, see the Telemetry API overview.

Using Mesh Config

If you used an IstioOperator CR to install Istio, add the following field to your configuration:

spec:
  meshConfig:
    accessLogFile: /dev/stdout

Otherwise, add the equivalent setting to your original istioctl install command, for example:

$ istioctl install <flags-you-used-to-install-Istio> --set meshConfig.accessLogFile=/dev/stdout

You can also choose between JSON and text by setting accessLogEncoding to JSON or TEXT.

You may also want to customize the format of the access log by editing accessLogFormat.

Refer to global mesh options for more information on all three of these settings:

• meshConfig.accessLogFile
• meshConfig.accessLogEncoding
• meshConfig.accessLogFormat

Default access log format

Istio will use the following default access log format if accessLogFormat is not specified:

[%START_TIME%] \"%REQ(:METHOD)% %REQ(X-ENVOY-ORIGINAL-PATH?:PATH)% %PROTOCOL%\" %RESPONSE_CODE% %RESPONSE_FLAGS% %RESPONSE_CODE_DETAILS% %CONNECTION_TERMINATION_DETAILS%
\"%UPSTREAM_TRANSPORT_FAILURE_REASON%\" %BYTES_RECEIVED% %BYTES_SENT% %DURATION% %RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)% \"%REQ(X-FORWARDED-FOR)%\" \"%REQ(USER-AGENT)%\" \"%REQ(X-REQUEST-ID)%\"
\"%REQ(:AUTHORITY)%\" \"%UPSTREAM_HOST%\" %UPSTREAM_CLUSTER% %UPSTREAM_LOCAL_ADDRESS% %DOWNSTREAM_LOCAL_ADDRESS% %DOWNSTREAM_REMOTE_ADDRESS% %REQUESTED_SERVER_NAME% %ROUTE_NAME%\n

The following table shows an example using the default access log format for a request sent from curl to httpbin:

Test the access log

1. Send a request from curl to httpbin:

   $ kubectl exec "$SOURCE_POD" -c curl -- curl -sS -v httpbin:8000/status/418
   ...
   < HTTP/1.1 418 Unknown
   ...
   < server: envoy
   ...
   I'm a teapot!
   ...

2. Check curl’s log:

   $ kubectl logs -l app=curl -c istio-proxy
   [2020-11-25T21:26:18.409Z] "GET /status/418 HTTP/1.1" 418 - via_upstream - "-" 0 135 4 4 "-" "curl/7.73.0-DEV" "84961386-6d84-929d-98bd-c5aee93b5c88" "httpbin:8000" "10.44.1.27:80" outbound|8000||httpbin.foo.svc.cluster.local 10.44.1.23:37652 10.0.45.184:8000 10.44.1.23:46520 - default

3. Check httpbin’s log:

   $ kubectl logs -l app=httpbin -c istio-proxy
   [2020-11-25T21:26:18.409Z] "GET /status/418 HTTP/1.1" 418 - via_upstream - "-" 0 135 3 1 "-" "curl/7.73.0-DEV" "84961386-6d84-929d-98bd-c5aee93b5c88" "httpbin:8000" "127.0.0.1:80" inbound|8000|| 127.0.0.1:41854 10.44.1.27:80 10.44.1.23:37652 outbound_.8000_._.httpbin.foo.svc.cluster.local default

Note that the messages corresponding to the request appear in logs of the Istio proxies of both the source and the destination, curl and httpbin, respectively. You can see in the log the HTTP verb (GET), the HTTP path (/status/418), the response code (418) and other request-related information.

Cleanup

Shutdown the curl and httpbin services:

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$ kubectl delete -f @samples/curl/curl.yaml@
$ kubectl delete -f @samples/httpbin/httpbin.yaml@

Disable Envoy’s access logging

Remove, or set to "", the meshConfig.accessLogFile setting in your Istio install configuration.

In the example below, replace default with the name of the profile you used when you installed Istio.

$ istioctl install --set profile=default
✔ Istio core installed
✔ Istiod installed
✔ Ingress gateways installed
✔ Installation complete