cmd/contour: Add support for json log formatter

[tsaarni]

This change enables Contour logs in JSON format as discussed in #4414 (comment).

The PR proposes new command line argument --log-format over generally preferred configuration CRD or config file field. The reasoning for new command line argument is to allow setting formatter for all sub-commands, not only serve, and setting it as early as possible, before CR is fetched from the API server or before config file is read from filesystem.

Fixes #4414

Signed-off-by: Tero Saarni tero.saarni@est.tech

[codecov]

Codecov Report

Merging #4486 (068240e) into main (e750132) will decrease coverage by 0.04%.
The diff coverage is 0.00%.

❗ Current head 068240e differs from pull request most recent head a336751. Consider uploading reports for the commit a336751 to get more accurate results

@@            Coverage Diff             @@
##             main    #4486      +/-   ##
==========================================
- Coverage   76.69%   76.64%   -0.05%     
==========================================
  Files         139      139              
  Lines       12511    12518       +7     
==========================================
  Hits         9595     9595              
- Misses       2669     2676       +7     
  Partials      247      247              

Impacted Files	Coverage Δ
cmd/contour/contour.go	0.00% <0.00%> (ø)

[tsaarni]

After specifying --log-format=json to set the Logrus JSON formatter, the logs looks like this:

{"level":"info","msg":"args: [serve --xds-address=0.0.0.0 --xds-port=8001 --envoy-service-http-port=8080 --envoy-service-https-port=8443 --contour-cafile=ca.crt --contour-cert-file=tls.crt --contour-key-file=tls.key --config-path=/home/tsaarni/work/devenvs/contour/configs/contour.yaml --log-format=json]","time":"2022-04-19T19:53:52+03:00"}
{"envoy-service-name":"envoy","envoy-service-namespace":"projectcontour","level":"info","msg":"Watching Service for Ingress status","time":"2022-04-19T19:53:52+03:00"}
{"context":"contourEventHandler","level":"info","msg":"started event handler","time":"2022-04-19T19:53:52+03:00"}
{"address":"127.0.0.1:6060","context":"debugsvc","level":"info","msg":"started HTTP server","time":"2022-04-19T19:53:52+03:00"}
{"address":"0.0.0.0:8000","context":"metricsvc","level":"info","msg":"started HTTP server","time":"2022-04-19T19:53:52+03:00"}
{"context":"xds","level":"info","msg":"waiting for informer caches to sync","time":"2022-04-19T19:53:52+03:00"}
{"context":"xds","level":"info","msg":"informer caches synced","time":"2022-04-19T19:53:52+03:00"}
{"caller":"leaderelection.go:248","context":"kubernetes","level":"info","msg":"attempting to acquire leader lease projectcontour/leader-elect...\n","time":"2022-04-19T19:53:52+03:00"}
{"address":"0.0.0.0:8001","context":"xds","level":"info","msg":"started xDS server type: \"contour\"","time":"2022-04-19T19:53:52+03:00"}
{"caller":"leaderelection.go:258","context":"kubernetes","level":"info","msg":"successfully acquired lease projectcontour/leader-elect\n","time":"2022-04-19T19:53:52+03:00"}
{"context":"StatusUpdateHandler","level":"info","msg":"started status update handler","time":"2022-04-19T19:53:52+03:00"}
{"context":"loadBalancerStatusWriter","level":"info","loadbalancer-address":"","msg":"received a new address for status.loadBalancer","time":"2022-04-19T19:53:52+03:00"}
{"context":"contourEventHandler","last_update":109610913,"level":"info","msg":"performing delayed update","outstanding":5,"time":"2022-04-19T19:53:52+03:00"}
{"connection":1,"context":"xds","error":"context canceled","level":"error","msg":"stream terminated","node_id":"envoy-pszrb","node_version":"v1.21.1","resource_names":null,"response_nonce":"1","time":"2022-04-19T19:54:47+03:00","type_url":"type.googleapis.com/envoy.config.cluster.v3.Cluster","version_info":"1"}
{"connection":2,"context":"xds","error":"context canceled","level":"error","msg":"stream terminated","node_id":"envoy-pszrb","node_version":"v1.21.1","resource_names":["default/echoserver/http"],"response_nonce":"1","time":"2022-04-19T19:54:47+03:00","type_url":"type.googleapis.com/envoy.config.endpoint.v3.ClusterLoadAssignment","version_info":"1"}
{"connection":3,"context":"xds","error":"context canceled","level":"error","msg":"stream terminated","node_id":"envoy-pszrb","node_version":"v1.21.1","resource_names":["ingress_http"],"response_nonce":"1","time":"2022-04-19T19:54:47+03:00","type_url":"type.googleapis.com/envoy.config.route.v3.RouteConfiguration","version_info":"1"}
{"connection":4,"context":"xds","error":"context canceled","level":"error","msg":"stream terminated","node_id":"envoy-pszrb","node_version":"v1.21.1","resource_names":null,"response_nonce":"1","time":"2022-04-19T19:54:47+03:00","type_url":"type.googleapis.com/envoy.config.listener.v3.Listener","version_info":"1"}

[youngnick]

This LGTM, we're trying to avoid adding command line flags in general, but I agree this is a good exception.

[sunjayBhatia]

worth merging for 1.21 i think, missed the RC but not a huge change, should be easy to cherry-pick

[tsaarni]

Thanks @sunjayBhatia! I should have asked myself if this will still fit into the release :)