Sanitize namespace flag consistently

[hoffm]

Problem

This plugin accepts a namespace var and creates a K8s namespace using that value. K8s namespaces must contain only lowercase alphanumeric characters and dashes, and begin with an alphanumeric character (reference).

To handle the possibility that users will provide values for namespace that are invalid as K8s namespace names, the plugin sanitizes the value before creating the namespace. This ensures that namespace creation does not fail due to an invalid name.

However, when the plugin calls kubectl rollout, it passes the unsanitized, user-provided namespace value. As a result, if the namespace var required sanitization to be a valid K8s namespace name, the rollout command will specify a namespace that does not exist, and will fail with the message:

namespaces "$NAMESPACE_VAR" not found

Fix

I see two options here:

1. Reject namespace values that are not valid K8s namespaces.
2. Sanitize the user-inputted value for use in the rollout command.

I've implemented (2) in checkParams.

I prefer approach because it allows the most flexibility for users. For instance, a common usage pattern is to pass the git branch name as the drone-gke namespace value. Branch names can have capital letters and other characters not allowed in K8s branch names. Option (2) allows users to continue the practice of using branch names without having to restrict the characters they can use in their git branches.

PR Form

If this is a change to the core functionality, did you make a corresponding PR to drone-eks?

https://github.com/nytimes/drone-eks/pull/75

• yes
• no
• n/a

Did you update the tests?

• yes
• no
• n/a

Did you update the docs?

I'm thinking of this as a bug fix, so I didn't think an update to the docs was warranted. Let me know if there's a change I should make.

• yes
• no
• n/a

[tonglil]

Thanks Michael, good find! I agree with you, the namespace var should be sanitized once and used consistently.

Do you mind refactoring the code so the sanitization and c.Set happens in the checkParams func as you described? That way c.String("namespace") will have the sanitized string everywhere it's called as checkParams happens early on.

Also, once this PR is approved, thank you in advance for importing the same changes into drone-eks!! 🫡

[hoffm]

Do you mind refactoring the code so the sanitization and c.Set happens in the checkParams func as you described? That way c.String("namespace") will have the sanitized string everywhere it's called as checkParams happens early on.

@tonglil Done!

[tonglil]

Thank you very much!