Add missing 'Source Code' heading in `krel` output

[jihoon-seo]

What happened:

'Source Code' heading is missing in krel-generated files.
Please refer to https://github.com/kubernetes/kubernetes/pull/101299/files .

[As-is]

## Downloads for v1.21.0

filename | sha512 hash
-------- | -----------

What you expected to happen:

[To-be]

## Downloads for v1.21.0

### Source Code

filename | sha512 hash
-------- | -----------

How to reproduce it (as minimally and precisely as possible):

Run krel changelog and/or krel release-notes commands, maybe..?

Anything else we need to know?:

• Related issue: Remove duplicates in krel release-notes output #1993
• Related issue: Auto-generated release notes file has bugs sig-release#1528
• CC: @wilsonehusin @pmmalinov01

Environment:

• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Others:

[wilsonehusin]

/priority backlog
/milestone v1.22

[jihoon-seo]

It seems that this is caused from:

release/pkg/notes/document/document.go

Lines 380 to 402 in c0d0213

	// Sort the files by their headers
	headers := [4]string{
	"", "Client Binaries", "Server Binaries", "Node Binaries",
	}
	files := map[string][]File{
	headers[0]: fileMetadata.Source,
	headers[1]: fileMetadata.Client,
	headers[2]: fileMetadata.Server,
	headers[3]: fileMetadata.Node,
	}
	for _, header := range headers {
	if header != "" {
	fmt.Fprintf(w, "### %s\n\n", header)
	}
	fmt.Fprintln(w, "filename | sha512 hash")
	fmt.Fprintln(w, "-------- | -----------")
	for _, f := range files[header] {
	fmt.Fprintf(w, "[%s](%s) | `%s`\n", f.Name, f.URL, f.Checksum)
	}
	fmt.Fprintln(w, "")
	}

---

[Suggestion]

-		"", "Client Binaries", "Server Binaries", "Node Binaries",
+		"Source Code", "Client Binaries", "Server Binaries", "Node Binaries",

[jihoon-seo]

Note:

[Capitalization issue]

• Client binaries, Server binaries, Node binaries in
  • pkg/changelog/const.go
  • pkg/notes/document/template.go
• Client Binaries, Server Binaries, Node Binaries in
  • pkg/notes/document/document.go
  • pkg/notes/document/document_test.go

[wilsonehusin]

good catch on capitalization too!

I wonder how we end up with "" -- my gut feeling is that this might be due to an off-by-one fix at some point. just trying to make sure there are no side effect if we add the suggested changes (which I agree with)

[jihoon-seo]

@wilsonehusin Thank you for your comment.

To check the effect of suggestions (here and here),

I ran krel release-notes --create-draft-pr --fork=jihoon-seo --tag v1.21.0 --fix,
and the results are as follows.

[Output file before applying suggestions]

[Output file after applying suggestions]

You can see that there is no "Downloads" section in the Markdown file generated by krel release-notes.
And the krel source code confirms that
func CreateDownloadsTable() in release/pkg/notes/document/document.go is called only by
func (c *Changelog) Run() in release/pkg/changelog/changelog.go,
which means that I should run krel changelog command to do "Downloads"-section-related test.

The problem here is that, I don't know how to use krel changelog.

https://kubernetes.slack.com/archives/C2C40FMNF/p1618996488120700

I want to try running krel changelog, but it gives error.

FYI: I made a softlink: /tmp/k8s -> /root/go/src/github.com/kubernetes/kubernetes

/tmp/k8s @ master branch ❯ krel changelog --branch release-1.21 --tag v1.21.0
INFO Using release branch release-1.21            
INFO Using local repository path /tmp/k8s         
INFO We're currently on branch: master            
FATA get latest branch commit: reference not found

❯ git checkout release-1.21
Switched to branch 'release-1.21'
Your branch is up to date with 'upstream/release-1.21'.

/tmp/k8s @ release-1.21 branch ❯ krel changelog --branch release-1.21 --tag v1.21.0
INFO Using release branch release-1.21            
INFO Using local repository path /tmp/k8s         
INFO We're currently on branch: release-1.21      
FATA get latest branch commit: reference not found

❯ git checkout release-1.20
Switched to branch 'release-1.20'
Your branch is up to date with 'upstream/release-1.20'.

/tmp/k8s @ release-1.20 branch ❯ krel changelog --branch release-1.21 --tag v1.21.0
INFO Using release branch release-1.21            
INFO Using local repository path /tmp/k8s         
INFO We're currently on branch: release-1.20      
FATA get latest branch commit: reference not found

Could you let me know what I am missing? 🤔

[wilsonehusin]

nice work! want to PR your changes and we can discuss there?

I never had to use krel changelog, so I'm not sure either 🤔 I'll give it a try

on links /tmp/k8s to your real path, you can use --repo to do that 😄

[jihoon-seo]

Okay, I will

• try --repo flag, and
• open a PR

next week! 😄