nginx $http_upgrade in openresty access_by_lua_block

Question

what is the name or how ca I call $http_upgrade of NGINX in OPENRESTY access_by_lua_block

so I can use it here

access_by_lua_block {
   ???
}

Answer 1

You can use either ngx.var.VARIABLE or ngx.req.get_headers API to get a value of any request header:

access_by_lua_block {
    ngx.log(ngx.INFO, ngx.var.http_upgrade)
    ngx.log(ngx.INFO, ngx.req.get_headers()['upgrade'])
}

From the documentation:

Note that the ngx.var.HEADER API call, which uses core $http_HEADER variables, may be more preferable for reading individual request headers.