openapi-generator/samples/server/echo_api/erlang-server

OpenAPI server library for Erlang

Overview

An Erlang server stub generated by OpenAPI Generator given an OpenAPI spec.

Prerequisites

1. Erlang/OTP (v27)

2. rebar3

3. Erlang libraries:

   • Cowboy
   • Ranch
   • Jesse

4. OpenAPI generator script openapi-generator-cli (for more information see OpenAPI Generator - Getting Started )

5. OpenAPI specification file in the current folder (for example petstore.yaml)

Getting started

Use erlang-server with rebar3

1. Create a folder with an Erlang application by using rebar3

   $ rebar3 new app http_server

2. Generate OpenAPI erlang-server project using openapi-generator

   $ openapi-generator-cli generate -g erlang-server -i petstore.yaml -o ./http_server --additional-properties packageName=openapi

3. Go into the http_server project folder

   $ cd http_server

   NOTE: The following generated files are now in the folder "http_server":

   • src/http_server*.erl, http_server.app.src -- Erlang application modules generated by rebar3

   • src/openapi*.erl, openapi.app.src -- REST API request handling modules generated by openapi-generator-cli

   • priv/openapi.json -- OpenAPI data in JSON format created by openapi-generator-cli

   • rebar.config -- Erlang project configuration file generated by openapi-generator-cli

4. Add the following line to the start/2 function in the src/http_server_app.erl:

    openapi_server:start(http_server,
        #{transport_opts => [{ip,{127,0,0,1}},
                             {port,8080} 
                            ]})

The updated start/2 in src/http_server_app.erl should look like this:

start(_StartType, _StartArgs) ->
    openapi_server:start(http_server,
        #{transport_opts => [{ip,{127,0,0,1}},
                             {port,8080} 
                            ]}),
    http_server_sup:start_link().

5. Update application configuration file http_server.app.src (in the src subfolder):

   1. Copy application name from http_server.app.src to openapi.app.src

   2. Copy {mod,...} rule from the http_server.app.src to openapi.app.src

   3. Copy openapi.app.src over http_server.app.src

      $ cp src/openapi.app.src src/http_server.app.src

   4. Remove openapi.app.src

      $ rm src/openapi.app.src

The updated src/http_server.app.src must be the only configuration file in the project and it should look like this:

{application, http_server,
    [   {description, "This is a sample petstore server"},
        {vsn, "1.0.0"},
        {registered, []},
        {mod, {http_server_app, []}},
        {applications, [kernel, stdlib, public_key, ssl, inets, ranch, cowboy]},
        {env, []},
        {modules, []},
        {licenses, ["Apache-2.0"]},
        {links, []}
    ]}.

6. Compile your http_server project

   $ rebar3 compile

7. Start Erlang virtual machine $ rebar3 shell

8. Start the application by running a following command in the rebar3 shell

   1> application:ensure_all_started(http_server).

   Alternatively, you could start your application with the rebar3 shell by adding the following lines to the rebar.config:

   {shell, [
       {apps, [http_server]}
   ]}.
   

Note: If you need to repeat code generation using openapi-generator-cli, but don't want to rewrite changes in files made manually, you could use file .openapi-generator-ignore in the project root folder. For example, such .openapi-generator-ignore will preserve manual changes done in the file rebar.conf (Point 8)

# OpenAPI Generator Ignore
rebar.config

To implement your own business logic, create a module called http_server_logic that implements the behaviour openapi_logic_handler. Refer to openapi_logic_handler documentation for details.