CODEWITHSUNDEEP
nginxopenresty
SomnusLee
SomnusLee

Reputation: 431

ngx_lua how to remove http request header

There is a param named "RedirectURL" in http request header. I want to remove it in ngx_lua and then send this request to RedirectURL, here is some snippet in nginx.conf

location /apiproxytest {

           set_by_lua $redirectURL '
                    return ngx.req.get_headers()["RedirectURL"]
            ';

            header_filter_by_lua '
                     ngx.header["RedirectURL"] = nil;
            ';

            echo "1:" $redirectURL;

            set_by_lua $redirectURL2 '
                    return ngx.req.get_headers()["RedirectURL"]
            ';
            echo "2:" $redirectURL2;

            proxy_pass $redirectURL;
}

When I test it use

curl --header "RedirectURL:www.google.com" xx.xx.xx.xx:xx/apiproxytest

I get result:

1: www.google.com
2: www.google.com

I don't know where the wrong is. Who can help me figure it out? Thanks for any help!

Upvotes: 3

Views: 11484

Answers (3)

Chao Zhang
Chao Zhang

Reputation: 61

You can use the API ngx.req.clear_header(header) or ngx.req.set_header(header, nil), which is

Upvotes: 1

fannheyward
fannheyward

Reputation: 19297

ngx.req.clear_header

location /apiproxytest {
    set_by_lua $redirectURL '
        local url = ngx.req.get_headers()["RedirectURL"]
        ngx.req.clear_header("RedirectURL")

        return url
    ';

    proxy_pass $redirectURL;
}

Upvotes: 6

Alexander Altshuler
Alexander Altshuler

Reputation: 3064

It is usual mistake. You think that nginx directives are executed in the same order as in config file. There are a lot phases of processing of nginx configuration files. Good, but long explanation: Nginx directive execution order

In their execution order the phases are post-read, server-rewrite, find-config, rewrite, post-rewrite, preaccess, access, post-access, try-files, content, and finally log.

set_by_lua - phase: rewrite
echo - phase: content
proxy_pass - phase: content
header_filter_by_lua - phase: output-header-filter

You may see unlisted phase - output-header-filter. Also I know about output-body-filter. These are special phases and implemented in different way then rewrite, contect etc phases. I cannot find a documentation for these phases. Any help are welcome! But obviously they cannot be early then content phase.

Your config's directives are executed in next order:

set_by_lua directives
echo and proxy_pass directives
header_filter_by_lua directives

So ngx.header["RedirectURL"] = nil really executed later and has no influence to your echo directives.

Upvotes: 3

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