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Tag: grafana

Grafana Alloy, parsing syslog RFC5424

2025/01/15 No Comments
Reading time: 31 – 51 minutes

Parsing syslog fields in a Grafana Alloy configuration file (config.alloy):


  stage.regex {
      expression = "^<(?P<priority>\\d|\\d{2}|1[1-8]\\d|19[01])>(?P<version>\\d{1,2})\\s(?P<timestamp>-|(?P<fullyear>[12]\\d{3})-(?P<month>0\\d|1[0-2])-(?P<mday>[0-2]\\d|3[01])T(?P<hour>[01]\\d|2[0-3]):(?P<minute>[0-5]\\d):(?P<second>[0-5]\\d|60)(?:\\.(?P<secfrac>\\d{1,6}))?(?P<numoffset>Z|[+-]\\d{2}:\\d{2}))\\s(?P<hostname>\\S{1,255})\\s(?P<appname>\\S{1,48})\\s(?P<procid>\\S{1,128})\\s(?P<msgid>\\S{1,32})\\s(?P<structureddata>-|\\[(?:[^\\[\\]]|\\\\.)*\\]) (?:\\s(?P<msg>.+))?$"
  }

  stage.labels  {
    values = {
      application = "appname",
      pid = "procid",
      msgid = "msgid",
      structureddata = "structureddata",
    }
  }

If Grafana Alloy logs are also parsed using this endpoint, it’s good to add next:

  stage.regex {
    expression = "^<(?P<priority>\\d|\\d{2}|1[1-8]\\d|19[01])>(?P<version>\\d{1,2})\\s(?P<timestamp>-|(?P<fullyear>[12]\\d{3})-(?P<month>0\\d|1[0-2])-(?P<mday>[0-2]\\d|3[01])T(?P<hour>[01]\\d|2[0-3]):(?P<minute>[0-5]\\d):(?P<second>[0-5]\\d|60)(?:\\.(?P<secfrac>\\d{1,6}))?(?P<numoffset>Z|[+-]\\d{2}:\\d{2}))\\s(?P<hostname>\\S{1,255})\\s(?P<appname>\\S{1,48})\\s(?P<procid>\\S{1,128})\\s(?P<msg>.*)$"
  }

  stage.output  {
    source = "msg"
  }

  stage.replace {
    expression = "(ts=\\S+\\s+level=\\S+\\s+)"
    source = "msg"
    replace = ""
  }

  stage.output {
    source = "msg"
  }

Docker Container Status as Prometheus Exporter Metrics

2024/11/07 No Comments
Reading time: 2 – 2 minutes

Tracking Docker container status in real time is a common challenge in DevOps. Popular tools like cAdvisor and the default Docker exporter for Prometheus often lack direct metrics for container states, meaning key insights—such as the number of containers that are running, stopped, or inactive—require complex workarounds. This limitation can complicate monitoring and lead to unreliable data.

Before creating docker_container_exporter, I relied on complex Prometheus queries to retrieve container statuses. This often involved calculations based on the last time a container was seen as active, but this approach had a major flaw: if the query time range didn’t match the last activity timestamp precisely, the data could be inaccurate or incomplete. Monitoring container states shouldn’t be this difficult.

With docker_container_exporter, this problem is solved. My tool captures real-time Docker container statuses, providing data on the number of running, stopped, and other container states, all in a Prometheus-compatible format. You can collect these metrics through a standard Prometheus polling process, or use agents like Grafana Alloy to push the data to Prometheus storage or compatible DB servers like Grafana Mimir or Thanos.

You can find my project in this GitHub repository: docker_container_exporter

In the README file, you’ll find details on how to use it, as well as instructions for integrating it with Grafana Alloy.

Add a New Dropdown Menu in OpenWRT LUCI

2023/10/17 No Comments
Reading time: 49 – 82 minutes

OpenWRT, the popular open-source Linux operating system designed for embedded devices, offers the LUCI interface for easy configuration and management. LUCI is essentially the web interface for OpenWRT, and while it’s already feature-rich, sometimes you may want to extend its functionalities based on your needs.

Recently, I had a requirement to enhance my OpenWRT LUCI interface. Specifically, I wanted to introduce a new menu named “Apps” in the LUCI dashboard. The objective was to have each entry within this new menu link to different applications installed on my device. And not just that! I wanted these application pages to pop open in new tabs for ease of access.

The Solution

The changes were made in a single file located at:

/usr/lib/lua/luci/controller/apps.lua

Within this file, I implemented the following code:

module("luci.controller.apps", package.seeall)

function index()
    local page

    page = entry({"admin", "apps"}, firstchild(), _("Apps"), 60)
    page.dependent = false

    entry({"admin", "apps", "portainer"}, call("serve_js_redirect", "https", "9443"), _("Portainer"), 10).leaf = true
    entry({"admin", "apps", "nodered"}, call("serve_js_redirect", "http", "1880"), _("NodeRED"), 20).leaf = true
    entry({"admin", "apps", "grafana"}, call("serve_js_redirect", "http", "3000"), _("Grafana"), 30).leaf = true
    entry({"admin", "apps", "prometheus"}, call("serve_js_redirect", "http", "9090"), _("Prometheus"), 40).leaf = true
end

function serve_js_redirect(protocol, port)
    local ip = luci.http.getenv("SERVER_ADDR")
    local url = protocol .. "://" .. ip .. ":" .. port
    luci.http.prepare_content("text/html; charset=utf-8")
    luci.http.write("<!DOCTYPE html><html><head><meta charset='UTF-8'><title>Redirecting...</title></head><body>")
    luci.http.write("<script type='text/javascript'>")
    luci.http.write("window.onload = function() {")
    luci.http.write("  var newWindow = window.open('".. url .."', '_blank');")
    luci.http.write("  if (!newWindow || newWindow.closed || typeof newWindow.closed == 'undefined') {")
    luci.http.write("    document.getElementById('manualLink').style.display = 'block';")
    luci.http.write("    setTimeout(function() { window.location.href = document.referrer; }, 60000);")  -- Redirigir después de 60 segundos
    luci.http.write("  }")
    luci.http.write("}")
    luci.http.write("</script>")
    luci.http.write("<p id='manualLink' style='display: none;'>The window didn't open automatically. <a href='".. url .."' target='_blank'>Click here</a> to open manually.</p>")
    luci.http.write("</body></html>")
end

Key Points

  • The index function is responsible for defining the new menu and its entries.
  • The serve_js_redirect function creates a web page that uses JavaScript to automatically open the desired application in a new browser tab.
  • A failsafe mechanism is added in the form of a link. If, for any reason (like pop-up blockers), the new tab doesn’t open automatically, the user has the option to manually click on a link to open the application.
  • The script also includes a feature that will redirect the user back to the previous page after 60 seconds if the new tab doesn’t open.

This modification provides a seamless way to integrate external applications directly into the LUCI interface, making navigation and management even more convenient!

Scripted Grafana dashboards

2017/11/24 No Comments

Reading time: < 1 minute A few minutes of video for explaining how to create dashboards on Grafana using Javascript code:

The code used for hello world script is available as a gist.

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