Replacement with regex support for selectors

[sda399]

Eschewed features

• This issue is not requesting templating, unstuctured edits, build-time side-effects from args or env vars, or any other eschewed feature.

What would you like to have added?

I would like to add regex support in replacement selectors

Update 2025-03-01:
We should be able to select or reject multiple objects, in a single selector block.
Source selection should not be affected, no regex support.
The options' block behaviour is unchanged:
- if multiple targets are found with regex, same options should apply to all matching targets. As declared in the target block.
- regex does not apply for source object selection, thus options behaviour remains the same.

Why is this needed?

Supporting regex in replacement selectors would:

• reduce redundancy of replacement blocks, by targeting multiple objects with regex
• harmonize replacement selectors with the patch selectors that already support regex
• make it possible to migrate from patches to replacements

Can you accomplish the motivating task without this feature, and if so, how?

example: replace image tag using deploy1 into depoly2, st1 and st2:

apiVersion: v1
kind: Deployment
metadata:
  name: deploy1
spec:
  template:
    spec:
      containers:
      - image: nginx:1.27.4
        name: nginx-tagged
---
apiVersion: v1
kind: Deployment
metadata:
  name: deploy2
spec:
  template:
    spec:
      containers:
      - image: nginx:1.5
        name: nginx-tagged
---
apiVersion: v1
kind: Statefulset
metadata:
  name: st1
spec:
  template:
    spec:
      containers:
      - image: nginx:1.5
        name: nginx-tagged
---
apiVersion: v1
kind: Statefulset
metadata:
  name: st2
spec:
  template:
    spec:
      containers:
      - image: nginx:1.5
        name: nginx-tagged

current solution:

replacements:
- source:
    kind: Deployment
    name: deploy1
    fieldPath: spec.template.spec.containers.0.image
  targets:
  - select:
      kind: Deployment
      name: deploy2
    fieldPaths:
    - spec.template.spec.containers.0.image
  - select:
      kind: StatefulSet
      name: st1
    fieldPaths:
    - spec.template.spec.containers.0.image
 - select:
      kind: StatefulSet
      name: st2
    fieldPaths:
    - spec.template.spec.containers.0.image

What other solutions have you considered?

proposed solution:

replacements:
- source:
    kind: Deployment
    name: deploy1
    fieldPath: spec.template.spec.containers.0.image
  targets:
  - select:
      kind: Deployment|StatefulSet
      name: deploy2|st.*
    fieldPaths:
    - spec.template.spec.containers.0.image

Anything else we should know?

No response

Feature ownership

• I am interested in contributing this feature myself! 🎉

[sda399]

If the projects' PR or triage process, requires any missing step or more details, I'll be happy to help 💯
@koba1t @stormqueen1990

[stormqueen1990]

/triage under-consideration
/lifecycle frozen

[stormqueen1990]

If the projects' PR or triage process, requires any missing step or more details, I'll be happy to help 💯 @koba1t @stormqueen1990

Hi there, @sda399! Thanks for filing this issue!

Could you please add a small bit to the issue describing how this change would impact the usage of the field options within the source and target for replacements? For instance, if create: true is used, could the new feature for regex impact that option?

[koba1t]

/assign

[sda399]

If the projects' PR or triage process, requires any missing step or more details, I'll be happy to help 💯 @koba1t @stormqueen1990

Hi there, @sda399! Thanks for filing this issue!

Could you please add a small bit to the issue describing how this change would impact the usage of the field options within the source and target for replacements? For instance, if create: true is used, could the new feature for regex impact that option?

Hi,
@stormqueen1990 thanks for considering this issue.

options' behaviour is unchanged:

• if multiple targets are found with regex, same options should apply to all matching targets. As declared in the target block.
• regex does not apply for source object selection, thus options behaviour remains the same.
• source selection is unchanged, any regex expression is treated as literal, thus name: pod.* will not find object with name: pod

[sda399]

I updated the issue description with the above details on options, to be more straight forward and readable.

[koba1t]

Thanks for responding. @stormqueen1990!

[koba1t]

Hi @sda399
Thanks for your work!
I think this idea is interesting and worth adopting.

However I believe this feature must be tested carefully because it can destroy existing functionality if done incorrectly.
For example, If the create option is enabled and reg-exp matches to an unexpected resource, an unintended field is created there, etc.

Therefore, could you please add at least the following test scenarios that I think are necessary?

• Select one resource from multiple resources by regular expression
• Select multiple resources, not all, with regular expressions from multiple resources
• Select multiple resource that contains one non-exist field that created by create: true
• Select multiple resource that contains multiple non-exist fields that created by create: true
• name: deploy2 didn't match name: deploy2-suffix and name: prefix-deploy2

If you have any questions, don't hesitate to ask!
If you come up with a scenario that you think should be tested, feel free to add!