How to do localization at the template level?

Question

go

Hello. Now the localization of the interface is done like this
template -> ru = interface in Russian
->uk = interface in Ukrainian
->br = interface in Brazilian
Somewhere they write that each phrase must be passed to the template using an array (some write constants or variables)
Now in my head thoughts are spinning about parsing the template, processing it with regular expressions and entering the finished template into a radish. Then the template is already pushed into html/template.
The processing of regular expressions will be something like this
In the template on disk, for example, we have %%in1%%
regular expression %%in1%%, replace it with the desired phrase (taking into account localization)
Phrases for replacement will be stored like this
map[string]string {
"%%in1%%" : "welcome",
"%%in2%%" : "exit",
"{{hello}}" : "Hi"
}

Answer 1

https://github.com/nicksnyder/go-i18n
and no need to invent anything. And for God's sake, call everything meaningful, not in1 but welcome and not in2 but exit