Installation

Add Barrel to your Erlang project, and the options for the server and the browser client.

You add Barrel to your project as a Hex dependency and start it like any other OTP application. Read this when you are setting up a new project, or adding Barrel to an existing one.

Requirements

• Erlang/OTP 28 or newer
• rebar3
• A C/C++ compiler and CMake (the vector layer builds a small NIF)

Add the dependency

Add barrel to your rebar.config:

{deps, [
    {barrel, "~> 1.0"}
]}.

Then start it. Starting barrel brings up the document and vector layers it composes:

{ok, _} = application:ensure_all_started(barrel).

You are ready to open a database.

Use just one layer

Barrel is one database made of independent libraries. If you only need one, depend on it directly instead:

{deps, [
    {barrel_docdb, "~> 1.0"},     %% documents only
    {barrel_vectordb, "~> 2.1"}   %% vectors only
]}.

Add the server

To expose the same database over HTTP (REST/JSON) and MCP, add barrel_server:

{deps, [
    {barrel_server, "~> 1.0"}
]}.

See Running the server for configuration and routes.

Use it in the browser

barrel-lite is the offline-first TypeScript client. It lives in the Barrel repo under clients/barrel-lite and syncs to a running barrel_server. See the browser client guide.