lua-init.conf

lua_shared_dict prometheus_metrics 10M;
lua_package_path "/lua-modules/?.lua;;";

init_by_lua_block {
  function string.starts(String,Start)
    return string.sub(String,1,string.len(Start))==Start
  end

  -- Load Prometheus module
  prometheus = require("prometheus").init("prometheus_metrics")
  metric_requests = prometheus:counter(
    "nginx_http_requests_total", "Number of HTTP requests", {"host", "status"})
  metric_latency = prometheus:histogram(
    "nginx_http_request_duration_seconds", "HTTP request latency", {"host"})
  metric_bytes = prometheus:counter(
    "nginx_http_request_size_bytes", "Total size of incoming requests")
  metric_response_sizes = prometheus:counter(
    "nginx_http_response_size_bytes", "Total size of outgoing reponses")
  metric_connections = prometheus:gauge(
    "nginx_http_connections", "Number of HTTP connections", {"state"})

  -- Load HTTP2 Push list
  local filePath = "/usr/share/nginx/www/http2-push-map.txt"
  local fileContent = io.open(filePath, "r");
  httpPushList = {}

  if fileContent then
    for line in fileContent:lines() do
      local url, assets = line:match("([^|]+)|(.+)")
      httpPushList[url] = assets
    end

    io.close(fileContent)
  else
    print("File "..filePath.." doesn\'t exist")
  end

  healthCheckPath = os.getenv("HEALT_CHECK_PATH")
}

log_by_lua_block {
  if ngx.var.request_uri ~= healthCheckPath then
    local host = ngx.var.host
    metric_requests:inc(1, {host, ngx.var.status})
    metric_latency:observe(ngx.now() - ngx.req.start_time(), {host})
    metric_bytes:inc(tonumber(ngx.var.request_length))
    metric_response_sizes:inc(tonumber(ngx.var.bytes_sent))
  end
}