Rich Preview Microservice

Elixir/Phoenix service for generating link previews with WhatsApp-style metadata extraction.

Features

• Open Graph/Twitter metadata parsing
• Concurrent request handling
• Auto-scale across CPU cores

Requirements

• Elixir 1.15+
• Erlang OTP 26+

Setup

1. Install dependencies:

mix deps.get

2. Start server:

mix phx.server

Usage

curl "http://localhost:4000/api/v1/preview?url=https://example.com"

Sample Response:

{
  "title": "Example Domain",
  "description": "This domain is for use in illustrative examples...",
  "image": "https://example.com/og-image.jpg",
  "url": "https://example.com"
}

Deployment

1. Production build:

MIX_ENV=prod mix release

2. Run with maximum CPU utilization:

ERL_FLAGS="+S 4:4" _build/prod/rel/rich_preview/bin/rich_preview start

Docker

FROM elixir:1.15

WORKDIR /app
COPY . .

RUN mix local.hex --force && \
    mix local.rebar --force && \
    mix deps.get && \
    mix release

CMD ["_build/prod/rel/rich_preview/bin/rich_preview", "start"]

For Ruby Developers

• Processes ≠ Threads: 1MB memory footprint vs 10KB
• Task.async ≈ Concurrent::Promise but more lightweight
• Pattern matching ≈ case/when with type checking