Find a replacement for drone/envsubst (not maintained anymore)

[guettli]

What would you like to be added (User Story)?

As a developer, I would like tools to fail if an environment variable is missing.

Detailed Description

At some places drone/envsubst gets used (for example hack/tools/bin/envsubst)

Up to now this tools silently replaces missing environment variables with an empty string.

Unfortunately this tool does not support an option to fail if an variable is not set.

I searched and found a8m/envsubst which supports failing on missing env variables.

Wasting time because missing env vars got silently replaced with empty strings is not fun.

The authors of drone/envsubst are a bit un-welcoming: They don't provide an issue tracker. This signals to me that it would be better to switch to a package which supports this feature, instead of adding this feature to drone/envsubst.

Label(s) to be applied

/kind feature
/area/code-organization

[sbueringer]

At a first glance sound reasonable to me.

Probably would be better if we replace it everywhere (including e.g. clusterctl)

[guettli]

@sbueringer thank you for your feedback. I hope I have time to create a PR during the next weeks.

[chrischdi]

👍 a8m/envsubst also seems to be the more healthier project, having more recent commits.

[guettli]

I think this would be a "good first issue". Does anyone have a young and motivated intern at hand?

[fabriziopandini]

If I'm not wrong with the proposed replacement we are going to lose a couple of the syntax supported by the current library (https://github.com/drone/envsubst vs https://github.com/a8m/envsubst#docs), this will be breaking for the users.

Have you considered contributing the syntax you are looking to into drone/envsubst?

[fabriziopandini]

/triage accepted
given that the discussion is ongoing, but let's make sure to not create disruption to users or to have a clear plan on how to handle this before moving forward

[guettli]

If I'm not wrong with the proposed replacement we are going to lose a couple of the syntax supported by the current library (https://github.com/drone/envsubst vs https://github.com/a8m/envsubst#docs), this will be breaking for the users.

Have you considered contributing the syntax you are looking to into drone/envsubst?

drone/envsubst does not provide an issue-tracker or any other way to provide feedback. That's why I created a PR to their README to make this clear to everybody. Up to now noone left a comment in my PR. For me this means the maintainers of drone/envsubst are not interested in a conversation with users: https://github.com/drone/envsubst/pull/33/files

I guess that a8m/envsubst is accepting PRs to get feature parity. I guess that should not be that difficult, since both are written in Go an both have the MIT license.

[fabriziopandini]

If drone stopped accepting issues it is a piece of bad news.
if we can easily feature parity in the alternative it will be great, otherwise, we will be forced to move handling all the communication with users. I will bring up the topic at the next office hours

[guettli]

I had a look at it. But bad news: a8m/envsubst replaces vars like $HOME, but the current implementation (drone/envsubst) does only replace variables in curly braces (for example ${HOME}). This change could break a lot of usages.

I created a PR to the corruently used repo drone/envsubst. Let's see if they accept it.

drone/envsubst#34