$ mkdir hello_joe $ cd hello_joe
This chapter explains how to get started using Erlang.mk.
The first step is always to create a new folder that will contain your project.
$ mkdir hello_joe $ cd hello_joe
Most people tend to put all their projects side by side in a common folder. We recommend keeping an organization similar to your remote repositories. For example, for GitHub users, put all your projects in a common folder with the same name as your username. For example $HOME/ninenines/cowboy for the Cowboy project.
At the time of writing, Erlang.mk is unlikely to be present in your Erlang distribution, or even in your OS packages.
The next step is therefore to download it:
$ wget https://erlang.mk/erlang.mk
Or:
$ curl https://erlang.mk/erlang.mk -o erlang.mk
Alternatively, just click on this link.
Make sure you put the file inside the folder we created previously.
An OTP application is an Erlang application that has a supervision tree. In other words, it will always have processes running.
This kind of project can be automatically generated by Erlang.mk.
All you need to do is use the bootstrap target:
$ make -f erlang.mk bootstrapSomething similar to the following snippet will then appear on your screen:
git clone https://github.com/ninenines/erlang.mk .erlang.mk.build Cloning into '.erlang.mk.build'... remote: Counting objects: 4035, done. remote: Compressing objects: 100% (12/12), done. remote: Total 4035 (delta 8), reused 4 (delta 4), pack-reused 4019 Receiving objects: 100% (4035/4035), 1.10 MiB | 784.00 KiB/s, done. Resolving deltas: 100% (2442/2442), done. Checking connectivity... done. if [ -f build.config ]; then cp build.config .erlang.mk.build; fi cd .erlang.mk.build && make make[1]: Entering directory '/home/essen/tmp/hello_joe/.erlang.mk.build' awk 'FNR==1 && NR!=1{print ""}1' core/core.mk index/*.mk core/index.mk core/deps.mk plugins/protobuffs.mk core/erlc.mk core/docs.mk core/test.mk plugins/asciidoc.mk plugins/bootstrap.mk plugins/c_src.mk plugins/ci.mk plugins/ct.mk plugins/dialyzer.mk plugins/edoc.mk plugins/elvis.mk plugins/erlydtl.mk plugins/escript.mk plugins/eunit.mk plugins/relx.mk plugins/shell.mk plugins/triq.mk plugins/xref.mk plugins/cover.mk \ | sed 's/^ERLANG_MK_VERSION = .*/ERLANG_MK_VERSION = 1.2.0-642-gccd2b9f/' > erlang.mk make[1]: Leaving directory '/home/essen/tmp/hello_joe/.erlang.mk.build' cp .erlang.mk.build/erlang.mk ./erlang.mk rm -rf .erlang.mk.build
This is Erlang.mk bootstrapping itself. Indeed, the file you initially downloaded contains nothing more than the code needed to bootstrap. This operation is done only once. Consult the Updating Erlang.mk chapter for more information.
Of course, the generated project can now be compiled:
$ make
Cheers!
An OTP library is an Erlang application that has no supervision tree. In other words, it is nothing but modules.
This kind of project can also be generated by Erlang.mk, using
the bootstrap-lib target:
$ make -f erlang.mk bootstrap-libErlang.mk will once again bootstrap itself and generate all the files for your project. You can now compile it:
$ make
Enjoy!
An OTP release is the combination of the Erlang RunTime System (ERTS) along with all the libraries and files that your node will need to run. It is entirely self contained, and can often be sent as-is to your production system and run without any extra setup.
Erlang.mk can of course bootstrap your project to generate releases.
You can use the bootstrap-rel target for this purpose:
$ make bootstrap-rel
This target can be combined with bootstrap or bootstrap-lib to
create a project that will build a release:
$ make -f erlang.mk bootstrap-lib bootstrap-relIt is often very useful to keep the top-level project for commands useful during operations, and put the components of the system in separate applications that you will then depend on. Consult the Packages and dependencies chapter for more information.
When you run make from now on, Erlang.mk will compile your
project and build the release:
$ make APP hello_joe.app.src GEN distclean-relx-rel GEN /home/essen/tmp/hello_joe/relx ===> Starting relx build process ... ===> Resolving OTP Applications from directories: /home/essen/tmp/hello_joe/ebin /usr/lib/erlang/lib /home/essen/tmp/hello_joe/deps ===> Resolved hello_joe_release-1 ===> Including Erts from /usr/lib/erlang ===> release successfully created!
The first time you run this command, Erlang.mk will download relx, the release building tool. So don’t worry if you see more output than above.
If building the release is slow, no need to upgrade your hardware just yet. Just consult the Releases chapter for various tips to speed up build time during development.
You can start the release using the ./_rel/hello_joe_release/bin/hello_joe_release
script, or simply run make run. The latter will also compile
your project and build the release if it wasn’t already:
$ make run APP hello_joe.app.src GEN distclean-relx-rel ===> Starting relx build process ... ===> Resolving OTP Applications from directories: /home/essen/tmp/hello_joe/ebin /usr/lib/erlang/lib /home/essen/tmp/hello_joe/deps ===> Resolved hello_joe_release-1 ===> Including Erts from /usr/lib/erlang ===> release successfully created! Exec: /home/essen/tmp/hello_joe/_rel/hello_joe_release/erts-7.0/bin/erlexec -boot /home/essen/tmp/hello_joe/_rel/hello_joe_release/releases/1/hello_joe_release -boot_var ERTS_LIB_DIR /home/essen/tmp/hello_joe/_rel/hello_joe_release/erts-7.0/../lib -env ERL_LIBS /home/essen/tmp/hello_joe/_rel/hello_joe_release/releases/1/lib -config /home/essen/tmp/hello_joe/_rel/hello_joe_release/releases/1/sys.config -args_file /home/essen/tmp/hello_joe/_rel/hello_joe_release/releases/1/vm.args -- console Root: /home/essen/tmp/hello_joe/_rel/hello_joe_release /home/essen/tmp/hello_joe/_rel/hello_joe_release heart_beat_kill_pid = 16389 Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] Eshell V7.0 (abort with ^G) (hello_joe@127.0.0.1)1>
Simple as that!
If you already have an application, or you want to have full control over what files will be created, you can setup Erlang.mk manually.
Erlang.mk is very easy to setup: all that you need to do is to create a folder, put Erlang.mk in it, and write a one line Makefile containing:
For a step by step:
$ mkdir hello_joe $ cd hello_joe $ curl https://erlang.mk/erlang.mk -o erlang.mk $ echo "include erlang.mk" > Makefile $ make
From that point onward you can create an src/ folder or start
using templates.
Erlang.mk defaults to tabs when creating files from templates. This is in part because of a personal preference, and in part because it is much easier to convert tabs to spaces than the opposite.
Use the SP variable if you prefer spaces. Set it to the number
of spaces per indentation level you want.
For example, if you prefer two spaces per indentation level:
$ make -f erlang.mk bootstrap SP=2
When you bootstrap the project initially, the variable automatically gets added to the Makefile, so you only need to provide it when you get started.
It is no secret that Erlang’s OTP behaviors tend to have some boilerplate. It is rarely an issue of course, except when creating new modules. That’s why Erlang.mk not only comes with templates for generating projects, but also individual modules!
You can list all available templates with the list-templates
target:
$ make list-templates
Available templates: cowboy_http cowboy_loop cowboy_rest cowboy_ws gen_fsm gen_server ranch_protocol supervisorTo generate a module, let’s say a gen_server, all you need to
do is to call make new with the appropriate arguments:
$ make new t=gen_server n=my_server
This will create a module located in src/my_server.erl
using the gen_server template.
This module is automatically compiled the next time you run
make:
$ make ERLC my_server.erl APP hello_joe.app.src
All that’s left to do is to open it in your favorite editor and make it do something!
Erlang.mk is a large text file. It can easily take a large part of
a git diff or a git grep command. You can avoid this by telling
Git that erlang.mk is a binary file.
Add this to your .gitattributes file. This is a file that you can create at the root of your repository:
erlang.mk -diffThe erlang.mk file will still appear in diffs and greps, but as a binary file, meaning its contents won’t be shown by default anymore.
During development, if you don’t remember the name of a target,
you can always run make help:
$ make help erlang.mk (version 1.2.0-642-gccd2b9f) is distributed under the terms of the ISC License. Copyright (c) 2013-2015 Loïc Hoguin <essen@ninenines.eu> Usage: [V=1] make [target]... Core targets: all Run deps, app and rel targets in that order app Compile the project deps Fetch dependencies (if needed) and compile them search q=... Search for a package in the built-in index rel Build a release for this project, if applicable docs Build the documentation for this project install-docs Install the man pages for this project check Compile and run all tests and analysis for this project tests Run the tests for this project clean Delete temporary and output files from most targets distclean Delete all temporary and output files help Display this help and exit erlang-mk Update erlang.mk to the latest version Bootstrap targets: bootstrap Generate a skeleton of an OTP application bootstrap-lib Generate a skeleton of an OTP library bootstrap-rel Generate the files needed to build a release new t=TPL n=NAME Generate a module NAME based on the template TPL list-templates List available templates ...
This guide should provide any other answer. If not, please open a ticket on the official repository and we will work on improving the guide.
Commercial support is available through Nine Nines. Please contact Loïc Hoguin by sending an email to contact@ninenines.eu.