¬ just serendipity 🍀 (not just serendipity)

Context: Helm charts use .Values.{foo} in templates/ for templating from values.yaml.

Goal: Return all unique values used in templates/. The intention for it is to add them all as defaults to values.yaml.

First attempt:

$ ack '\.Values\.'

One could proceed manually from here, but this is not very ergonomic in big helm charts.

A better (and more precise) attempt is:

$ ack '\.Values[\.\w+]+'

This will match .Values.config.foo, in addition to .Values.foo.

To return only the matched strings, add -o:

$ ack -o '\.Values[\.\w+]+'

Here is a real example:

$ ack -o '\.Values[\.\w+]+'
[...]
values.yaml
349:29:.Values.global.prometheus_scrape_interval
863:29:.Values.global.prometheus_scrape_interval
903:20:.Values.global.global_grafana_ingest_url

To return only the values, add -h (it will hide the filenames):

$ ack -o -h '\.Values[\.\w+]+'
[...]
.Values.global.prometheus_scrape_interval
.Values.global.prometheus_scrape_interval
.Values.global.global_grafana_ingest_url

Now all that is left to do is to pipe it to sort -u.

$ ack -o -h '\.Values[\.\w+]+' | sort -u
[...]
.Values.global.prometheus_scrape_interval
.Values.global.global_grafana_ingest_url

It turns out that grep also has a -o flag with a similar behavior.