How to enclose a multiline command within an until-do loop in YAML - shell

Question

I need to use an until-do loop in the "script" section of a YAML file, and the command in the until clause visually benefits from being broken into multiple lines:
- >
helm upgrade $(...) /helm/charts/ -f .(...)
--install
--set host=(...)
--set tag=(...)
--set image=(...)
--namespace (...)
I've tried using this formatting to enclose the helm upgrade command within an until-do loop:
- >
until helm upgrade $FOO helm/charts/ -f ./(...)
--install
--set imagePullSecret=(...)
--set host=(...) --set tag=(...)
--set image=(...)
--namespace (...); do
helm uninstall $FOO
done
...which results in the errors:
(...): line 161: --install: command not found
(...): line 162: --set: command not found
(...): line 163: --set: command not found
(...): line 164: --set: command not found
(...): line 165: --namespace: command not found
Error: uninstall: Release not loaded: (...): release: not found
However, if I abandon efforts to make this more readable:
- >
until helm upgrade foo helm/charts/ -f ./(...) --install --set imagePullSecret=(...) --set host=(...) --set tag=(...) --set image=(...) --namespace (...); do
helm uninstall foo
done
...the command runs as expected:
Release "bar" has been upgraded. Happy Helming!
What is the correct way to enclose a multiline command within an until-do loop in YAML?

Answer 1

A literal block scalar (started with >) in YAML will fold line endings into spaces between consecutive non-empty lines… unless one of the lines is more indented than the base indentation of the scalar.
This has been designed so that something like
>
lorem ipsum
dolor sit amet
* one
* two
will be parsed as
"lorem ipsum dolor sit amet\n\n *one\n *two\n"
since the * symbols are more indented than the lorem ipsum line.
In your case, this means that if you want to break the command into multiple lines but want it parsed as a single line, you mustn't indent the continuation lines:
- >
until helm upgrade $FOO helm/charts/ -f ./(...)
--install
--set imagePullSecret=(...)
--set host=(...) --set tag=(...)
--set image=(...)
--namespace (...); do
helm uninstall $FOO
done
You can indent the helm uninstall since it should be executed as separate command.
If you dislike this and want to indent the continuation lines, you need to escape the resulting newlines:
- >
until helm upgrade $FOO helm/charts/ -f ./(...) \
--install \
--set imagePullSecret=(...) \
--set host=(...) --set tag=(...) \
--set image=(...) \
--namespace (...); do
helm uninstall $FOO
done