red

Red is a terminal log analysis tools.

Usage

Pipe JSON stream logs into red and specify a few fields to display. For example using with kubernetes:

kubectl logs ... | red level message

You will see combined logs with trend sparkline and total count.

Install

go install github.com/antonmedv/red@latest

Usage

Pipe newline-delimited JSON into red and list fields to group by:

... | red <field> [<field> ...]

Keys:

• ↑ / ↓ — select a row
• Enter — open detail view for the selected row
• Esc — close detail view

Flags:

• -trend <duration> — trend window (default 10s)
• -distance <n> — Levenshtein distance for grouping (default 3)

Kubernetes

kubectl logs -f deploy/api | red level message

Caddy access logs

Caddy's default access log is JSON, so it works directly. Most useful fields are nested under request, so flatten them with jq first.

Enable JSON access logs in your Caddyfile:

example.com {
    log {
        output file /var/log/caddy/access.log
        format json
    }
    reverse_proxy localhost:8080
}

Then watch live traffic:

tail -F /var/log/caddy/access.log \
  | jq -c '{status, method: .request.method, uri: .request.uri, ip: .request.client_ip}' \
  | red status method uri

Visitor stats recipes

Top requested paths:

tail -F /var/log/caddy/access.log \
  | jq -c '{uri: .request.uri}' \
  | red uri

Top client IPs (visitors):

tail -F /var/log/caddy/access.log \
  | jq -c '{ip: .request.client_ip}' \
  | red ip

Status code distribution:

tail -F /var/log/caddy/access.log \
  | jq -c '{status}' \
  | red status

Top user agents (with longer trend window):

tail -F /var/log/caddy/access.log \
  | jq -c '{ua: (.request.headers."User-Agent"[0] // "-")}' \
  | red -trend 1m ua

Nginx access logs

Nginx's default log format is plain text. Convert to JSON first — either by configuring nginx to emit JSON, or by piping through a parser.

Configure nginx for JSON access logs in nginx.conf:

log_format json_combined escape=json
  '{'
    '"time":"$time_iso8601",'
    '"remote_addr":"$remote_addr",'
    '"method":"$request_method",'
    '"uri":"$request_uri",'
    '"status":$status,'
    '"bytes_sent":$bytes_sent,'
    '"referer":"$http_referer",'
    '"user_agent":"$http_user_agent"'
  '}';

access_log /var/log/nginx/access.log json_combined;

Then:

tail -F /var/log/nginx/access.log | red status method uri

Top visitor IPs:

tail -F /var/log/nginx/access.log \
  | jq -c '{remote_addr}' \
  | red remote_addr

Ideas for visitors analytics UI

Now red show one table only. For watching site visitors in live mode, more nice UI can help very much. Here is some simple ideas — written by simple words, without difficult terms.

Big numbers on top

Show some big numbers on top of screen, so you can see most important informations from one look:

• Visitors now — how many peoples was on site in last 5 minutes
• Page views per minute — how much site is busy
• Errors per minute — how many 4xx and 5xx answers from server
• Middle page time — how fast pages is loading

This numbers change in live time when new logs is coming.

Divide screen on panels

Instead of one table, show many small panels near each other:

┌─────────────────────┬──────────────────────┐
│  Top pages          │  Top countries       │
│  /                  │  USA                 │
│  /blog              │  Great Britain       │
│  /pricing           │  Germany             │
├─────────────────────┼──────────────────────┤
│  Status codes       │  Visitors now: 42    │
│  ▇▇▇▇▇ 200 (89%)    │  Page views: 1.2k/m  │
│  ▇ 404 (8%)         │  Errors: 3/m         │
│  ▏ 500 (3%)         │  Middle load: 240ms  │
└─────────────────────┴──────────────────────┘

Every panel watch one thing. You see all picture without scrolling.

Colors with sense

Use colors, so problems is visible:

• Green — all good (200 OK)
• Yellow — be careful (404 Not Found, slow pages)
• Red — bad (500 errors, very very slow pages)

When you see many red — something is broken. When all green — everything works in normal mode.

Map of world for visitors

Draw small ASCII map of world. Make light countries where visitors are sitting right now. More bright color means more peoples from this country.

For this need IP-to-country base (free MaxMind GeoLite2 is good and works without problems).

Click for go deeper

Click on row in "Top pages" — and other panels make filter only for this page. Click on country — see visitors only from there. Press Esc for come back.

So red become not only viewer, but tool for research.

Pause and back in time

Pause button for stop screen. Very comfortable when something interesting happen and you want look on it without new logs running up.

Small time slider for scroll back on last few minutes.

Find strange traffic

Mark rows what look not normal:

• Same IP open many pages very fast (maybe is bot)
• Many 404 from one IP (somebody search secret files)
• Sudden big quantity of one user agent
• New country what never was before

Show small warning icon near row. Click on it for see why.

Browsers and devices

Panel what show what peoples use:

Browsers           Devices
Chrome   ▇▇▇▇ 62%   Mobile  ▇▇▇ 48%
Safari   ▇▇ 24%     Desktop ▇▇▇ 45%
Firefox  ▇ 10%      Tablet  ▏ 7%
Other    ▏ 4%

This data is parsing from User-Agent header.

Search line

Search line on top. Write path, IP or status code, and all UI make filter for this. Press Esc for clean.

Web UI with login and tracking script

Terminal is good for engineers, but not all peoples like black window with text. Web UI in browser can be much more friendly for everybody.

How it can work:

1. Tracking script — small JavaScript file (like 1-2 kilobyte), site owner put it on every page:

   <script defer src="https://red.example.com/track.js"
           data-site="my-blog"></script>
   

   Script send small ping when visitor open page. Ping contain: page URL, referer, screen size, language, user agent. No cookies, no personal datas — so GDPR is happy.

2. Server part — red receive this pings on endpoint like /api/event, save them on disk or in small base (SQLite works fine without big setup).

3. Login page — simple form with email and password. After login user see dashboard. One account can watch many sites.

   ┌──────────────────────────────┐
   │     Welcome to red           │
   │                              │
   │  Email:    [______________]  │
   │  Password: [______________]  │
   │                              │
   │         [  Sign in  ]        │
   │                              │
   │  Forgot password? Register   │
   └──────────────────────────────┘
   

   For begin can be enough one admin user from config file. Later — make normal registration with email confirm.

4. Dashboard in browser — same ideas like terminal UI (big numbers, panels, map, colors), but with mouse, animation and more space. Charts can be drawn beautiful with library like Chart.js or just SVG by hand.

5. Share link — generate public link what show statistics for one site, without login. Useful when you want show numbers to client or on Twitter.

Why this is good:

• Site owner not need to keep terminal open all day
• Can open dashboard from phone in bus
• Can give access to colleagues without SSH key
• Looks more professional for non-technical peoples

What red already have for this — JSON logs processing and grouping logic. Need to add: HTTP server, tracking endpoint, login system, HTML pages. Big job, but very interesting.

Why this is important

Now red is good for engineers what read logs. With this ideas it can also help to not-engineers — product peoples, marketing, support — for see what is happening on site, and not learn terminal commands.

License

MIT