Helm override list in values.yml so that original list is NOT propagated

Question

Let's says I have a default values.yml in a Helm chart that looks like:

orders:
  - order1
  - order2
  - order3

Now, I want to override THE ENTIRE LIST, using the usual -f my-values.yaml syntax, and it contains something like

orders:
 - order66

My problem is that in this way, the order66 item gets MERGED in the list, so the list now has:

orders:
  - order1
  - order2
  - order3
  - order66

...while I want instead to OVERWRITE the entire list with my custom values.

An example of a real use-case is scrape_configs in Prometheus values.yml.

What is the syntax to use?

Answer 1

If it's just one simple variable, you should be able to just run:

# helm install my_chart ./mychart -f values.yaml --set my_option=my_value

as explained HERE (search for --set in that document).

However if it's a longer set of values, things get more complicated. You can try to use --set-file $file option and move your values in there.

As shown HERE search for --set-file key=, so in your case you'll have:

# cat my_values_file
- order1
- order2
- order3
- order66

# helm install my_chart ./mychart -f values.yaml --set-file orders=my_values_file

You can also try running a different approach in "cleaning" the variable and settings it afterward:

# helm install my_chart ./mychart --set orders=null -f values.yaml

So that it's going to be emptied and then set with the content of what's in values.yaml

Be sure to run:

# helm install my_chart ./mychart --dry-run --debug --set orders=null -f values.yaml

to verify what the command will do before actually applying it.

Also, be aware that the order matter, as the right-most operator takes precedence.

Cheers