feat: Add probes to Helm chart

[microamp]

Fixes #429

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.80%. Comparing base (c80251d) to head (7fb7d3b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #430      +/-   ##
==========================================
+ Coverage   82.72%   82.80%   +0.07%     
==========================================
  Files         124      126       +2     
  Lines        2599     2611      +12     
==========================================
+ Hits         2150     2162      +12     
  Misses        449      449              

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[microamp]

The test ran.

ietf/health/tests.py . [ 55%]

https://github.com/ietf-tools/www/actions/runs/8778595524/job/24085285664?pr=430#step:6:267

---

The probes are listed under the pod definition (checked locally). e.g.

kubectl describe pod www-wagtail-7bcdd765fd-4fnps

Containers:
  www:
    ...
    Liveness:       http-get http://:http/healthz delay=0s timeout=5s period=10s #success=1 #failure=3
    Readiness:      http-get http://:http/healthz delay=0s timeout=5s period=10s #success=1 #failure=3
    Startup:        http-get http://:http/healthz delay=0s timeout=5s period=10s #success=1 #failure=6
    ...
  ...

---

The readiness and liveness probes (both every 10 seconds) from the Gunicorn logs (checked locally). e.g.

tail -f /tmp/gunicorn-stdout---supervisor-u1v0g6n8.log

...
10.244.0.1 - - [22/Apr/2024:06:03:11 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
10.244.0.1 - - [22/Apr/2024:06:03:11 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
10.244.0.1 - - [22/Apr/2024:06:03:21 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
10.244.0.1 - - [22/Apr/2024:06:03:21 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
10.244.0.1 - - [22/Apr/2024:06:03:31 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
10.244.0.1 - - [22/Apr/2024:06:03:31 +0100] "GET /healthz HTTP/1.1" 200 2 "-" "kube-probe/1.28" "-"
...

[microamp]

Note to self: Changed the prefix from chore to feat as a new endpoint has been introduced.