Вам (возможно) не нужен сервер

location /03/ {
    access_by_lua_block {
        if ngx.var.http_magic ~= 'unicorn' then
            ngx.exit(ngx.HTTP_FORBIDDEN)
        end
    }

    try_files /welcome.html =404;
}

location /04/ {
    content_by_lua_block {
        local f = io.open('.../file', 'r')
        local content = f:read('*all');
        -- . . .

location /04/ {
    content_by_lua_block {
        local res = ngx.location.capture('/@04/')
        ngx.say('(function() { ' .. res.body .. ' })()')
    }
}
location /@04/ {
    internal;
    try_files /04.js = 404;
}

lua_shared_dict hits 1m;
init_by_lua_block {
    local hits = ngx.shared.hits
    hits:set('value', 0)
}

location /05/ {
    content_by_lua_block {
        local hits = ngx.shared.hits
        local value = hits:get('value') + 1
        hits:set('value', value)
        ngx.say('hits: ' .. tostring(value))
    }
}

lua_shared_dict hits 1m;
location /05-ideomatic/ {
    content_by_lua_block {
        local hits = ngx.shared.hits
        local value = hits:incr('value', 1)
        ngx.say('hits: ' .. tostring(value))
    }
}

lua_shared_dict referers 16m;
location /06/ {
    access_by_lua_block {
        local referers = ngx.shared.referers
        local domain = (ngx.re.match(ngx.var.http_referer,
            '([a-z]+://)?([^/]+)', 'i') or {})[2]
        local hits = (referers:get(domain) or 0) + 1
        referers:set(domain, hits, 30) -- 30 seconds

        if hits > 30 then
            ngx.say('Go away')
            ngx.exit(ngx.HTTP_TOO_MANY_REQUESTS)
        end
    }

$ curl nginx/06/ -H referer:example.com
Welcome
...
$ curl nginx/06/ -H referer:example.com
Welcome
$ curl nginx/06/ -H referer:example.com
Go away
$ sleep 30
$ curl nginx/06/ -H referer:example.com
Welcome

$ ab -n 50000 -c 400 _h referer:example.com nginx/06/
Requests per second:    10300.81 [#/sec] (mean)
Time per request:       38.832 [ms] (mean)

Percentage of the requests served within a certain time (ms)
  50%     38
  66%     39
  75%     40
  80%     41
  90%     42
  95%     43
  98%     44
  99%     44
 100%   1061 (longest request)

location /07/ {
    content_by_lua_block {
        ngx.sleep(math.random())
    }

    log_by_lua_block {
        local statistics = ngx.shared.statistics
        local time = ngx.var.request_time

        statistics:incr('request_time-sum', time)
        statistics:incr('request_time-total', 1)
    }
}

location = /07-status/ {
    content_by_lua_block {
        local statistics = ngx.shared.statistics
        local sum = statistics:get('request_time-sum')
        local total = statistics:get('request_time-total')

        ngx.say('average request time: ', sum / total, ' for ', total, ' requests')
    }
}

$ curl localhost/07/
$ curl localhost/07/
$ curl localhost/07/
$ curl localhost/07/
$ curl localhost/07-status/
average request time: 0.74 for 4 requests

init_by_lua_block {
    local function save ()
        ngx.location.capture('/my-upstream/save', {
            method = ngx.HTTP_POST,
            body = concat_my_stuff()
        })
    end

    ngx.timer.every(60, save)
}

lua_package_path '/blah/blah/?.lua;;'
init_by_lua_block {
    require('jsapi')
}
location ~ ^/2\.1(?<version>[-.]\w+) {
    set_by_lua_block $real_version {
        local jsapi = require('jsapi')
        -- . . .
        return jsapi.rewrite(ngx.var.version)
    }

    proxy_pass ...2.1$real_version;
}

location /isalive {
    content_by_lua {
        local jsapi = require('jsapi')
        local responses = ngx.location.capture_multi(jsapi.versions_urls)
        for i, reponse in ipairs(reponses) do
            if response.status ~= ngx.HTTP_OK then
                ngx.exit(reponse.status)
            end
        end
    }
}