From 939a2b042c8a0b1a64823cbf642b9415a1a2c306 Mon Sep 17 00:00:00 2001
From: Ben Langfeld <ben@langfeld.me>
Date: Mon, 18 Jan 2016 19:13:59 -0200
Subject: [PATCH] Parameterise runtime app path

---
 README.md               | 3 +++
 elixir_buildpack.config | 1 +
 lib/erlang_funcs.sh     | 8 ++++----
 lib/path_funcs.sh       | 6 +++++-
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 2e55f3b8..32c1946c 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,9 @@ config_vars_to_export=(DATABASE_URL)
 
 # A command to run right after compiling the app
 post_compile="pwd"
+
+# Set the path the app is run from
+runtime_path=/app
 ```
 
 
diff --git a/elixir_buildpack.config b/elixir_buildpack.config
index 79d4ac5a..7f97cc09 100644
--- a/elixir_buildpack.config
+++ b/elixir_buildpack.config
@@ -2,3 +2,4 @@ erlang_version=18.1.3
 elixir_version=1.2.0
 always_rebuild=false
 config_vars_to_export=(DATABASE_URL)
+runtime_path=/app
diff --git a/lib/erlang_funcs.sh b/lib/erlang_funcs.sh
index f2140c61..b42b939d 100644
--- a/lib/erlang_funcs.sh
+++ b/lib/erlang_funcs.sh
@@ -31,10 +31,10 @@ function install_erlang() {
   mkdir -p $(erlang_build_path)
   tar zxf ${cache_path}/$(erlang_tarball) -C $(erlang_build_path) --strip-components=1
 
-  rm -rf /app/.platform_tools/erlang
-  mkdir -p /app/.platform_tools
-  ln -s $(erlang_build_path) /app/.platform_tools/erlang
-  $(erlang_build_path)/Install -minimal /app/.platform_tools/erlang
+  rm -rf $(runtime_erlang_path)
+  mkdir -p $(runtime_platform_tools_path)
+  ln -s $(erlang_build_path) $(runtime_erlang_path)
+  $(erlang_build_path)/Install -minimal $(runtime_erlang_path)
 
   cp -R $(erlang_build_path) $(erlang_path)
   PATH=$(erlang_path)/bin:$PATH
diff --git a/lib/path_funcs.sh b/lib/path_funcs.sh
index e83cb33d..7f462bdc 100644
--- a/lib/path_funcs.sh
+++ b/lib/path_funcs.sh
@@ -6,8 +6,12 @@ function erlang_path() {
   echo "$(platform_tools_path)/erlang"
 }
 
+function runtime_platform_tools_path() {
+  echo "${runtime_path}/.platform_tools"
+}
+
 function runtime_erlang_path() {
-  echo "/app/.platform_tools/erlang"
+  echo "$(runtime_platform_tools_path)/erlang"
 }
 
 function elixir_path() {