How to rewrite location in nginx depending on the client-browser's language?

You can manage $language_suffix by this setting when you cannot add AcceptLanguageModule module into your system.

rewrite (.*) $1/$http_accept_language

A more resilient approach would use a map:

map $http_accept_language $lang {
        default en;
        ~es es;
        ~fr fr;
}

...

rewrite (.*) $1/$lang;

I know this is a very old thread, but I found it when trying to solve the same problem. Just wanted to share the solution I finally came with. It is different to the ones published above as if there are several languages mentioned in the Accept-Language, it will pick the first mentioned among the ones we can serve.

    #
    # Determine what language to redirect to
    # this sets the value of $lang variable to the language depending on the contents of Accept-Language request header
    # the regexp pattern automatically matches a known language that is not preceded by another known language
    # If no known language is found, it uses some heuristics (like RU for (uk|be|ky|kk|ba|tt|uz|sr|mk|bg) languages)
    #
    map $http_accept_language $lang {
        default en;
        "~*^((|,)\s*(?!(ru|es|fr|pt|en))\w+(-\w+)?(;q=[\d\.]+)?)*(|,)\s*en\b" en;
        "~*^((|,)\s*(?!(ru|es|fr|pt|en))\w+(-\w+)?(;q=[\d\.]+)?)*(|,)\s*es\b" es;
        "~*^((|,)\s*(?!(ru|es|fr|pt|en))\w+(-\w+)?(;q=[\d\.]+)?)*(|,)\s*ru\b" ru;
        "~*^((|,)\s*(?!(ru|es|fr|pt|en))\w+(-\w+)?(;q=[\d\.]+)?)*(|,)\s*fr\b" fr;
        "~*^((|,)\s*(?!(ru|es|fr|pt|en))\w+(-\w+)?(;q=[\d\.]+)?)*(|,)\s*pt\b" pt;
        "~*(^|,)\s*(uk|be|ky|kk|ba|tt|uz|sr|mk|bg)\b" ru;
        "~*(^|,)\s*(ca|gl)\b" es;
    }

    ...

    rewrite (.*) $1/$lang;

The limitation of this solution is that it assumes the languages in the Accept-Language header are listed in the order of their preference. Usually this is true, but it is not officially required. For example, if the header is "Accept-Language: da, en-US;q=0.1, pt-BR;q=1", the variable $lang will be set to "en" because it comes before "pt" even though pt has larger weight.

Choosing the right language taking into account all the weights does not seem to be possible in nginx without external scripts. This solution was good enough for me in all practical cases and it did not require any external modules.

Lua example above is fine, but will fail with error 500 if browser does not send any Accept-Language headers.

Add this on top of it:

if ngx.var.http_accept_language == nil then
ngx.redirect("/en/")
end

In addition to @Marks answer above which does not honor language preferences. Here's a LUA chunk of code parsing Accept-Language Header value into language and preference value

-- need two LUA regex cause LUA's default regex is pretty broken
-- In my opinion a killer argument against using / supporting LUA

rx = "%s*([a-zA-Z-]+)%s*;%s*q%s*=%s*(%d*.?%d+)"
rx2 = "%s*([a-zA-Z-]+)%s*"

-- (arg .. ",") => concatenation operation
for chunk in (arg .. ","):gmatch("([^,]*),") do
    lang, q = string.match(chunk, rx)
    if (not lang) then
        lang = string.match(chunk, rx2)
        q = 1.0
    end
    print(string.format("lang=[%s] q=[%s]",lang, tonumber(q * 1.0)))
end

When applying, I'm getting:

$ lua demo.lua 'en-US , de , fr ; q = 0.1 , dk;q=1 '
lang=[en-US] q=[1.0]
lang=[de] q=[1.0]
lang=[fr] q=[0.1]
lang=[dk] q=[1.0]

$ lua demo.lua ' de'
lang=[de] q=[1.0]

$ lua demo.lua ' de;'
lang=[de] q=[1.0]

$ lua demo.lua ' de;q'
lang=[de] q=[1.0]

$ lua demo.lua ' de;q='
lang=[de] q=[1.0]

$ lua demo.lua ' de;q=0'
lang=[de] q=[0.0]

$ lua demo.lua ' de;q=0.1'
lang=[de] q=[0.1]

Eventually I'm using than a LUA script like below to redirect:

rx = "%s*([a-zA-Z-]+)%s*;%s*q%s*=%s*(%d*.?%d+)"
rx2 = "%s*([a-zA-Z-]+)%s*"


sup = {de = 0, en = 0, dk = 0}       -- supported languages
win = {lang = "en", q = 0}           -- default values / winner

for chunk in (arg[1] .. ","):gmatch("([^,]*),") do
    lang, q = string.match(chunk, rx)
    if (not lang) then
        lang = string.match(chunk, rx2)
        q = 1.0
    end
    lang = string.lower(lang)
    -- handle only supported languages
    if (sup[lang]) then
        q = tonumber(q)
        -- update winner table if a better match is found
        if (win.q < q) then
            win.q = q
            win.lang = lang
        end
    end
end

-- which language pref?
print(string.format("winner: %s",win.lang))

This gives:

$ lua test.lua 'en-US;q=.7 , de;q=0.9 , fr ; q = 0.1 , dk ; q  =  1 '
winner: dk