Adding typed_json log format

[tenshinhigashi]

Description

The purpose of this PR is to add typed_json log format as an option for envoy logging.

Related Issues

https://github.com/datawire/apro/issues/3408

Testing

All testing was done locally. I compared logs between standard json and the new typed_json.

This was the module I applied:

apiVersion: getambassador.io/v3alpha1
kind:  Module
metadata:
  name: ambassador
spec:
  config:
    envoy_log_type: typed_json
    envoy_log_format:
      {
        "protocol": "%PROTOCOL%",
        "duration": "%DURATION%"
      }

When looking at the logs after some simple curls, this is what I see:

Note the duration values are ints rather than strings.

When looking at the logs with the same Module but json log type:

The duration values are strings.

If no envoy_log_format is provided, the default format is the same as json's. Here is a full log line without any envoy_log_format:

{"requested_server_name":null,"user_agent":"curl/7.79.1","method":"GET","response_flags":"-","upstream_local_address":"10.42.0.12:55614","duration":0,"upstream_cluster":"quote_default","start_time":"2023-08-30T15:22:44.539Z","response_code":200,"downstream_local_address":"10.42.0.12:8443","upstream_service_time":"0","downstream_remote_address":"10.42.0.1:40191","x_forwarded_for":"10.42.0.1","upstream_transport_failure_reason":null,"path":"/backend/","authority":"34.133.232.144","istio_policy_status":null,"protocol":"HTTP/1.1","bytes_sent":220,"upstream_host":"10.43.1.125:80","request_id":"ae2e5f5f-d14d-4714-b138-37b3c4aefa70","bytes_received":0}

Note that the values are still formatted as expected.

• null instead of "-"
• int values where expected such as duration, response_code, bytes_sent, bytes_received, etc

Checklist

• Does my change need to be backported to a previous release?

  • What backport versions were discussed with the Maintainers in the Issue?

• I made sure to update CHANGELOG.md.

  Remember, the CHANGELOG needs to mention:

  • Any new features
  • Any changes to our included version of Envoy
  • Any non-backward-compatible changes
  • Any deprecations

• This is unlikely to impact how Ambassador performs at scale.

  Remember, things that might have an impact at scale include:

  • Any significant changes in memory use that might require adjusting the memory limits
  • Any significant changes in CPU use that might require adjusting the CPU limits
  • Anything that might change how many replicas users should use
  • Changes that impact data-plane latency/scalability

• My change is adequately tested.

  Remember when considering testing:

  • Your change needs to be specifically covered by tests.
    • Tests need to cover all the states where your change is relevant: for example, if you add a behavior that can be enabled or disabled, you'll need tests that cover the enabled case and tests that cover the disabled case. It's not sufficient just to test with the behavior enabled.
  • You also need to make sure that the entire area being changed has adequate test coverage.
    • If existing tests don't actually cover the entire area being changed, add tests.
    • This applies even for aspects of the area that you're not changing – check the test coverage, and improve it if needed!
  • We should lean on the bulk of code being covered by unit tests, but...
  • ... an end-to-end test should cover the integration points

• I updated DEVELOPING.md with any any special dev tricks I had to use to work on this code efficiently.

• The changes in this PR have been reviewed for security concerns and adherence to security best practices.

[LanceEa]

Overall it LGTM, just one suggestion to reduce duplication.