Chapter 4. Updating Erlang.mk

The first time you use Erlang.mk, it will bootstrap itself. It always uses the most recent version for this, so you don’t have to update after creating your project.

Later on though, updating becomes a necessity. Erlang.mk developers and contributors relentlessly improve the project and add new features; it would be a waste not to benefit from this.

That’s why updating Erlang.mk is so simple. All you need to do is to call make erlang-mk:

$ make erlang-mk
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 | 1000.00 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/emkg/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/emkg/hello_joe/.erlang.mk.build'
cp .erlang.mk.build/erlang.mk ./erlang.mk
rm -rf .erlang.mk.build

All that’s left to do is to commit the file!

Yep, it’s that easy.

Erlang.mk allows you to customize which components are to be included in the erlang.mk file. The WITHOUT variable allows you to remove components from the default Erlang.mk build. The build.config file lets you define exactly what goes in (including your own code!), and in what order.

The WITHOUT file contains the list of components to exclude from the build. For example, to exclude the package index and the EDoc plugin when bootstrapping your application:

$ make -f erlang.mk bootstrap WITHOUT="index plugins/edoc"

The generated Erlang.mk will never include those components when you update it, until you change your mind and use the WITHOUT variable again when you upgrade:

$ make erlang-mk WITHOUT=index

The build.config file is automatically used when you bootstrap Erlang.mk or when you update it with make erlang-mk.

The build.config file contains the list of all files that will be built into the resulting erlang.mk file. You can start from the most recent version and customize to your needs.

You can also name the file differently or put it in a separate folder by modifying the value for ERLANG_MK_BUILD_CONFIG. You can also tell Erlang.mk to use a different temporary directory by changing the ERLANG_MK_BUILD_DIR variable.

If you want to use a different repository or a specific commit for updating, you may use the variables ERLANG_MK_REPO and ERLANG_MK_COMMIT.