Set $HOME to $CNB_APP_DIR at launch for compatibility with profile.d …

…scripts

See: heroku#23

Squashed commit of the following:

commit 1c3d01d
Author: Kamal Nasser <[email protected]>
Date:   Tue Feb 2 00:42:02 2021 +0200

    set HOME env to app dir at runtime for profile.d scripts

bin/build

@@ -10,6 +10,7 @@ source_dir="${bp_dir}/target"
 
 layers_dir="${1:?}"
 platform_dir="${2:?}"
+app_dir="$(pwd)"
 
 # translate new stack ID to old stack ID
 export STACK="$CNB_STACK_ID"
@@ -24,13 +25,18 @@ cache_dir="${layers_dir}/shim"
 mkdir -p "${cache_dir}"
 echo "cache = true" > ${layers_dir}/shim.toml
 
-"${target_dir}/bin/compile" "$(pwd)" "${cache_dir}" "${platform_dir}/env"
+"${target_dir}/bin/compile" "$app_dir" "${cache_dir}" "${platform_dir}/env"
 
 # copy profile.d scripts into a layer so they will be sourced
 if [[ -d .profile.d ]]; then
 	profile_dir="${layers_dir}/profile"
+
 	mkdir -p "${profile_dir}/profile.d"
 	cp .profile.d/* "${profile_dir}/profile.d/"
+
+	mkdir -p "${profile_dir}/env.launch"
+	echo -n "$app_dir" > "${profile_dir}/env.launch/HOME.override"
+
 	echo "launch = true" > "${profile_dir}.toml"
 fi
 
@@ -41,4 +47,4 @@ if [[ -f "${target_dir}/export" ]]; then
 fi
 
 # run bin/release, read Procfile, and generate launch.toml
-"${bp_dir}/bin/release" "${target_dir}" "${layers_dir}" "${platform_dir}" "$(pwd)"
+"${bp_dir}/bin/release" "${target_dir}" "${layers_dir}" "${platform_dir}" "$app_dir"