barista

Barista serves up hot lmugs of LFE for your simple LFE-native HTTP needs.

Contents

• Introduction
• Installation
• Usage
• Creating Custom Modules
• License

Introduction ↟

Barista is a stand-alone, simple HTTP server. Or more accurately, barista is LFE code that wraps the Erlang/OTP httpd HTTP server. It is intended for development/demo purposes and non-critical services.

Installation ↟

Just add it to your rebar.config deps:

    {deps, [
        {barista, "0.3.3"}
    ]}.

And then do the usual:

    rebar3 compile

Usage ↟

To try out the default no-op/pass-through handler, you can do this (after rebar3 compile):

rebar3 lfe repl

lfe> (set `#(ok ,svr) (barista:start))

This will start an HTTP server with the default barista options. You can use curl to try it out:

curl "http://localhost:5099/"

or

curl -XPOST \
     -H "Content-Type: application/x-www-form-urlencoded" \
     -d "c=3&d=42" \
     "http://localhost:5099/order?a=1&b=2"

You can override the default options like so:

lfe> (set `#(ok ,svr) (barista:start '(#(port 9099))))

Additionally, you can provide a config file that may be used to provide options for starting up barista (which is really the inets httpd service):

lfe> (set `#(ok ,svr) (barista:start '(#(config-file "configs/sys.config"))))

That expects the inets httpd configuration to be in a nested proplist under the following:

[{inets,
 [{services,
  [{httpd, ... }]}]}].

If your configuration is in a different part of the configuration, you just need to supply a list of the keys that point to it, e.g.:

lfe> (set `#(ok ,svr) (barista:start '(#(config-file "configs/sys.config")
                                       #(config-keys (my-app httpd)))))

Finally, to stop barista:

lfe> (barista:stop svr)

Creating Custom Modules ↟

The Erlang inets httpd server supports the creation of modules (see the documentation for the various mod_* httpd modules). The example module barista-passthrough implements the httpd module contract: a single do/1 function is all that is needed. The argument it takes is the inets httpd request record mod found in inets/include/httpd.hrl.

In addition to this, the barista-passthrough defines a handle/3 function very much in line with the sort of thing that Elli developers do when creating routes for their web applications.

License ↟

Copyright © 2014-2021, Duncan McGreggor

Apache License, Version 2.0