Docker

Ember is available as a container image built from scratch (no OS, no shell: just the static binary and CA certificates).

Quick Start

docker run --rm --network host ghcr.io/alexandre-daubois/ember

Default Behavior

The image defaults to --daemon --expose :9191. This means:

• No TUI (headless mode)
• Prometheus metrics available on port 9191 (/metrics and /healthz)
• Connects to the Caddy admin API at http://localhost:2019

Network Configuration

Ember needs to reach the Caddy admin API. Two options:

Host Network

Use --network host so the container shares the host's network stack:

docker run --rm --network host ghcr.io/alexandre-daubois/ember

Custom Address

Point Ember to the Caddy service by name or IP:

docker run --rm ghcr.io/alexandre-daubois/ember --daemon --expose :9191 --addr http://caddy:2019

Custom Flags

Override the default CMD by appending flags:

docker run --rm --network host ghcr.io/alexandre-daubois/ember \
  --daemon --expose :9191 --interval 2s --metrics-prefix myapp

Docker Compose

A minimal setup with Caddy and Ember as a sidecar:

services:
  caddy:
    image: caddy:latest
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./Caddyfile:/etc/caddy/Caddyfile

  ember:
    image: ghcr.io/alexandre-daubois/ember
    network_mode: "service:caddy"
    depends_on:
      - caddy

With this setup, Ember runs in the same network namespace as Caddy and can reach localhost:2019 directly.

Caution: The image is built from scratch: there is no shell, no exec, and no debugging tools inside the container. Use docker logs to read Ember's stderr output.

See Also

• Getting Started
• Prometheus Export