Ember Setup Guide

Ember is a zero-config, read-only terminal dashboard that connects to Caddy's admin API to display real-time traffic metrics, latency percentiles, and FrankenPHP thread introspection. This skill walks through installation, Caddy configuration, and first launch.

Prerequisites

• A running Caddy server (any recent version)
• For FrankenPHP thread-level metrics (method, URI, duration, memory): FrankenPHP 1.12.2+. Older versions only show thread index and state.

Step 1: Install Ember

Offer the user the installation method that fits their environment:

Homebrew (macOS / Linux)

brew install alexandre-daubois/tap/ember

On macOS, Gatekeeper may block the first run because the binary is not notarized. If this happens, remove the quarantine flag:

xattr -d com.apple.quarantine $(which ember)

Go

go install github.com/alexandre-daubois/ember/cmd/ember@latest

Docker

docker run --rm --network host alexandredaubois/ember

The image is also available on GHCR as ghcr.io/alexandre-daubois/ember. The Docker image runs in daemon mode by default (headless, Prometheus metrics on :9191). See the ember-production skill for Docker deployment details.

Step 2: Configure Caddy

Ember needs two things from Caddy: the admin API and the metrics directive. Both go in the Caddyfile global block.

Minimal Caddyfile

{
    admin localhost:2019
    metrics
}

example.com {
    respond "Hello, world!" 200
}

Why the admin API matters: Ember connects to localhost:2019 to read configuration, thread states, and Prometheus metrics. If the admin block is missing, Caddy disables the API entirely.

Why the metrics directive matters: Without it, Caddy doesn't expose caddy_http_requests_total, caddy_http_request_duration_seconds, or other HTTP counters. Ember's traffic table will be empty.

Why explicit hostnames matter: Use example.com { ... } rather than :80 { ... }. Caddy only adds the host label to metrics when the route has a host matcher. Without it, all traffic appears under a single * row instead of per-host breakdown.

Quick verification

Run these to confirm Caddy is ready:

# Check admin API is reachable
curl -s http://localhost:2019/config/ | head -c 100

# Check metrics are flowing
curl -s http://localhost:2019/metrics | grep caddy_http_requests_total

If the first returns JSON, the API is up. If the second returns a line with caddy_http_requests_total, metrics are enabled.

Step 3: Run ember init

This is the recommended way to validate the setup. It checks everything and can fix missing metrics automatically:

ember init

What it does:

1. Verifies the admin API is reachable
2. Checks that HTTP servers are configured
3. Enables the metrics directive via the API if missing (no Caddy restart needed)
4. Detects FrankenPHP presence, threads, and workers
5. Confirms metrics are actually flowing

Useful flags:

• ember init -y: skip confirmation prompts
• ember init -yq: skip prompts and suppress output (for scripting)
• ember init --addr https://prod:2019 --ca-cert ca.pem: remote/TLS setup

Step 4: Launch Ember

ember

Ember connects to http://localhost:2019 and starts polling every second. If FrankenPHP is detected, a second tab appears automatically.

Connecting to a different address

ember --addr http://your-host:2019

Or via environment variable:

export EMBER_ADDR=http://your-host:2019
ember

Adjusting the polling interval

ember --interval 2s

TLS and mTLS

For production Caddy instances served over HTTPS:

Custom CA certificate (private PKI, self-signed)

ember --addr https://caddy.internal:2019 --ca-cert /path/to/ca.pem

Mutual TLS (mTLS)

When Caddy requires client certificates:

ember --addr https://caddy.internal:2019 \
  --ca-cert /path/to/ca.pem \
  --client-cert /path/to/client.pem \
  --client-key /path/to/client-key.pem

Skip TLS verification (development only)

ember --addr https://localhost:2019 --insecure

This disables all certificate verification, never use in production.

Basic Navigation

Once Ember is running:

Environment Variables

All main flags have environment variable equivalents, useful for containers and scripts:

Explicit flags always take precedence over environment variables.

Shell Completions

Set up tab completion for your shell:

# Bash
ember completion bash > /etc/bash_completion.d/ember

# Zsh
ember completion zsh > "${fpath[1]}/_ember"

# Fish
ember completion fish > ~/.config/fish/completions/ember.fish

# PowerShell
ember completion powershell | Out-String | Invoke-Expression

What's Next

• If something isn't working, check the ember-troubleshoot skill
• For production deployment (daemon mode, Prometheus, Docker), see the ember-production skill