Self referencing templates.

[blmhemu]

I have a single yaml in which is both the datasource and the target. As a very simple example, consider this.

key1: val1
key2: val2
key3:
  key4: val4
key5: |
  1 - {{ key1 }}
  2 - {{ key2 }}
  3.4 - {{ key3.key4 }}

Is such self-referencing datasource and target possible ? If so how do I do it ? Thanks 🙏

[hairyhenderson]

Hi @blmhemu - this is possible with some slight modification.

foo.yaml:

key1: val1
key2: val2
key3:
  key4: val4
key5: |
  1 - {{ .key1 }}
  2 - {{ .key2 }}
  3.4 - {{ .key3.key4 }}

$ gomplate -c .=foo.yaml -f foo.yaml
key1: val1
key2: val2
key3:
  key4: val4
key5: |
  1 - val1
  2 - val2
  3.4 - val4

This uses the foo.yaml file as both a datasource (used as the default context) and the template.

This works because the file is valid YAML before being processed.

Hope this helps!

[blmhemu]

Awesome ! Thanks a lot. This answers my original question. In the same vein I have one more question :) -

• I have multiple yaml files like foo1.yml, foo2.yml, etc... and would like to first merge all these into one yaml file say foo_merged.yml and then use the above logic for foo_merged.yml.

For ^ this case, should I merge the yamls using a different program (and then use gomplate on the merged file) or would gomplate be able to accomplish the above end-to-end workflow ?

[hairyhenderson]

Have you looked at the merge: datasource? See https://docs.gomplate.ca/datasources/#using-merge-datasources

That being said, that'll only work for the datasource, not for the template. Though maybe you could hack something up with a mix of include and tmpl.Inline 🤔...

I'm thinking something like:

gomplate -d 'data=merge:foo1.yml|foo2.yml|foo3.yml' -i '{{ tmpl.Inline (include "data") (ds "data") }}'

But you'll have to play around with that to get it working. IMO it'd be better to split the data from the template so it's easier to reason about.

[blmhemu]

Hey ! Thanks for the clear answer. I did look at the merge - But unfortunately only this section and hence could not find it :) Anyways, thanks for the help, will tinker it out and report if I have more to say.