gWebTail: tail -f in the browser for teams without SSH access

A familiar scene: a new build is deployed to a test server and a developer asks “can you send me the log?”. Someone with SSH access logs in, runs tail -f, copies a chunk into a chat — and ten minutes later does it again.

Giving everyone SSH access to the server is not an option. Setting up a full logging stack — ELK, Loki with Grafana, Graylog — for a test environment or a small on-prem installation is often overkill. What people actually need is simple: open a browser, pick a log file, watch it grow.

That’s what gWebTail does.

What it is

gWebTail is a small Go application that serves a web page and streams new lines from log files to the browser over a WebSocket — essentially tail -f with a UI.

• File picker — every file in the configured log directory appears in a drop-down.
• Live tail — new lines appear as soon as they are written; the server checks files every 500 ms by default.
• Highlighting — type warn:, ERROR or a request ID and every match is highlighted.
• Line limit and auto-scroll — keep the last N lines in the browser and follow the end of the file, or turn auto-scroll off to read calmly.
• Start / Stop — pause the stream when you need to look at something.
• No external dependencies — HTML and CSS are embedded in the binary. No CDN, no internet access needed, so it works in closed on-prem networks.

It handles log truncation too: if a file is truncated (for example by logrotate with copytruncate), gWebTail notices the size drop and starts again from the new content.

Running it

The easiest way is the multi-arch Docker image (amd64 and arm64):

docker run -d --name gwebtail \
  -p 127.0.0.1:8080:8080 \
  -v /var/log/myapp:/logs:ro \
  docker.io/bsv9/gwebtail

Then open http://localhost:8080.

A few details that save time:

• Mount the log directory read-only (:ro) — gWebTail only needs to read.
• The container runs as an unprivileged user (UID 10001). Log files must be readable by it; many files under /var/log are 640 root:adm, so either adjust permissions for the application’s own log directory or point the app to write its logs somewhere readable.
• Only files directly in the log directory are listed, not subdirectories. Mount the specific directory you want to show.

With Docker Compose:

services:
  gwebtail:
    image: docker.io/bsv9/gwebtail
    container_name: gwebtail
    ports:
      - "127.0.0.1:8080:8080"
    volumes:
      - /var/log/myapp:/logs:ro
    restart: unless-stopped

Or build and run the binary directly (Go 1.22+):

git clone https://github.com/bsv9/gwebtail.git
cd gwebtail
go build -o gwebtail
LOG_DIR=/var/log/myapp ./gwebtail -port 8080

Configuration

When you start tailing, gWebTail first sends the end of the file (up to -buffersize bytes, cut at a line boundary), then streams new content as it arrives.

Security: keep it private

gWebTail has no authentication, and log files often contain things that shouldn’t leave the team: internal hostnames, user IDs, sometimes tokens. Treat it as an internal tool:

• Don’t expose it to the internet. Bind it to localhost or an internal interface (-p 127.0.0.1:8080:8080 above), or limit access with a firewall.
• Put a reverse proxy with authentication in front if more people need it — Nginx or Traefik with basic auth, or SSO via oauth2-proxy. Remember to pass WebSocket upgrade headers for the /ws endpoint.
• Run it in a container with only the log directory mounted, read-only. That way the process can’t see anything else on the host, whatever happens.

When to use it — and when not

gWebTail is a good fit for:

• test and staging servers, where developers want to watch their deployment;
• small on-prem installations at customers, where you can’t install a logging stack and the network is isolated;
• giving support or QA a read-only window into one application’s logs;
• a Raspberry Pi or home server, to watch what your services are doing.

It is not a replacement for centralized logging. If you need search across weeks of history, many servers, retention policies, dashboards or alerting, use Loki, Graylog or the ELK stack — gWebTail only shows what is in the files right now.

Summary

• One small binary or Docker image, no dependencies, works offline.
• Browser-based tail -f with highlighting, line limit and auto-scroll.
• Mount logs read-only, keep it on an internal network, and put authentication in front if more people need access.

The project is open source under the MIT license: github.com/bsv9/gwebtail.

Thinking about proper centralized logging for your infrastructure? Let’s talk.