helm-diff doesn't include values from stdin for helm3 version

[ruslanloman]

Hi,
Unfortunately previous PR was close as state, but this fix is still needed, so I've created a new one. Please review it once you have time. thanks!

There is an issue in helm-diff for helm3 version, it doesn't include values from stdin. For helm2 it works as expected.

$ cat values-10.yaml                                                               
lolkek:                                                                            
  helloword: test                                                                  
  new:                                                                             
    ohoho:                                                                         
      values-10: lolodddd10 

Current behavior:

$ cat values-10.yaml | helm3 diff upgrade test_helm . --allow-unreleased --values -
                                                                         
+ # Source: test_helm/templates/configMap.yaml                                     
+ apiVersion: v1                                                                   
+ kind: ConfigMap                                                                  
+ metadata:                                                                        
+   name: game-demo                                                                
+ data:                                                                            
+   user-interface.properties: |                                                   
+     null         

Expected behavior with applied fix:

$ cat values-10.yaml | helm3 diff upgrade test_helm . --allow-unreleased --values -
                                                                                 
+ # Source: test_helm/templates/configMap.yaml                                     
+ apiVersion: v1                                                                   
+ kind: ConfigMap                                                                  
+ metadata:                                                                        
+   name: game-demo                                                                
+ data:                                                                            
+   user-interface.properties: |                                                   
+     ohoho:

[ruslanloman]

@mumoshu applied your changes. thanks!

[mumoshu]

Did this change actually work for you?

I'm afraid we're missing tmpfile.Close() here, that I think is required to ensure writes are persisted. We should call Close() regardless of the write err is nil or not so wrapping it into another function call would be easier to read.

See writeExistingValues for your reference!

[ruslanloman]

Yes, it worked pretty well. I got your point regarding closing the tempfile. tbh i don't want to overcomplicate it by adding one more function, so just added one more if condition.

[mumoshu]

LGTM. Thanks for your effort!

[mumoshu]

I appreciate your contribution ☺️