feat: additional template functions

[matkam]

Description

Adds a few useful text/template functions:

• replaceAll: strings.replaceAll
• isIPv6: exposes an existing function that returns a bool to let you know if a string is an IPv6 address
• isIPv4: a new function that returns a bool to let you know if a string is an IPv4 address

N/A

Checklist

• Unit tests updated
• End user documentation updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: matkam / name: Mathew Kamkar (b5a6cbd, 5798069, b37cb51, 664ea01, 3f77b0a, 8d52be2, 20e5eb9, db35373, ae43729, a6851a2, db55aa1)

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[k8s-ci-robot]

Hi @matkam. Thanks for your PR.

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[johngmyers]

Please submit a CLA per the instructions above.

[matkam]

Please submit a CLA per the instructions above.

Yes 👍
I'm just waiting on my employer to click the button.

[matkam]

@johngmyers we are good to go here 👍

[johngmyers]

Is this function intended to return true for IPv4-mapped IPv6 addresses?

[matkam]

It just returns true when the input string is an IPv4 address. It'll return false if its IPv6 or otherwise invalid IP address.

[johngmyers]

https://go.dev/play/p/2SNDvrwxdh-

[matkam]

how about something like this?

func isIPv4String(input string) bool {
	netIP := net.ParseIP(input)
	return netIP != nil && netIP.To4() != nil && !strings.Contains(input, ":")
}

[johngmyers]

Sprig has replace, which is similar. Perhaps we should follow their syntax?

[johngmyers]

/ok-to-test

[matkam]

Sprig has replace, which is similar. Perhaps we should follow their syntax?

does replace work differently? I could also add strings.replace to the FuncMap.

[johngmyers]

I believe replace has the arguments in a different order. See the documentation in https://masterminds.github.io/sprig/strings.html

[matkam]

I believe replace has the arguments in a different order. See the documentation in https://masterminds.github.io/sprig/strings.html

sprig looks like a nice package. how about just importing it and using hermeticTxtFuncMap like this:

func parseTemplate(fqdnTemplate string) (tmpl *template.Template, err error) {
	if fqdnTemplate == "" {
		return nil, nil
	}
	
	funcs := sprig.HermeticTxtFuncMap()
	funcs["isIPv6"] = isIPv6String
	funcs["isIPv4"] = isIPv4String

	return template.New("endpoint").Funcs(funcs).Parse(fqdnTemplate)
}

[matkam]

@johngmyers let me know what you think. I've updated the template functions to include Sprig's hermetic text functions, and fixed the isIPv4String function so that it only returns true for valid IPv4 strings.

[mloiseleur]

/retitle feat: additional template functions

[simonostendorf]

Hello, I would like to see this merged and released. What needs to be done?

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[szuecs]

Please no import for a single func.

[matkam]

@szuecs it includes several useful go template functions: https://github.com/go-task/slim-sprig/blob/master/functions.go

Would you rather not include these functions, and only keeping isIPv4?

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/lifecycle stale

[matkam]

/remove-lifecycle stale

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