Allow disabling recipe interpolation

[FlatMapIO]

There are many tools that use go-template to get field values, such as
kubectl get secret nfluxdb2-auth -n monitoring --template={{index .data "admin-password"}} | base64 -d
which are difficult to render with the escept.

I tried {{ '{{index .data "admin-password"}}' }}
and "{{" '{{index .data "admin-password"}}' "}}"
that didn't work properly

[casey]

Did you get this working?

I think you'll need another set of single quotes:

foo:
  kubectl get secret nfluxdb2-auth -n monitoring --template=--template='{{ '{{index .data "admin-password"}}' }}' | base64 -d

I think it would be good to be able to disable interpolation in individual recipes. It would probably need attributes, as proposed #604. It might be hard though, since the lexer would need to be know when it was lexing a recipe without interpolation.

[FlatMapIO]

I finally got the right result, but I think it's an inelegant solution, and in a complex scenario, the expression becomes extremely difficult to read.

kubectl get secret influxdb2-auth -n monitoring --template='{{'{{index .data "admin-password"}}'}}' | base64 -d

[casey]

I agree, it's definitely not very nice, and ideally could be improved.

[casey]

I just released v0.8.5, which allows escaping a {{ by writing {{{{, so this should be much better now.