Modernize the builder

* Uses the buildpack installer for custom buildpacks
* Uses helpers to format the output
* Uses the environment variables for the start & exec commands

Author: mjonuschat

builder/build-helpers.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+function echo_title() {
+  echo $'\e[1G----->' $*
+}
+
+function echo_normal() {
+  echo $'\e[1G      ' $*
+}
+
+function ensure_indent() {
+  while read line; do
+    if [[ "$line" == --* ]]; then
+      echo $'\e[1G'$line
+    else
+      echo $'\e[1G      ' "$line"
+    fi
+  done
+}

builder/builder

@@ -0,0 +1,120 @@
+#!/bin/bash
+set -eo pipefail
+source $(dirname $0)/build-helpers.sh
+
+app_dir=/app
+build_root=/tmp/build
+cache_root=/cache
+buildpack_root=/tmp/buildpacks
+
+mkdir -p $app_dir
+mkdir -p $cache_root
+mkdir -p $buildpack_root
+mkdir -p $build_root/.profile.d
+
+cd $app_dir
+
+# In heroku, there are two separate directories, and some
+# buildpacks expect that.
+cp -r . $build_root
+
+## Get custom buildpack
+
+if [[ -f ".env" ]]; then
+	source ".env"
+fi
+
+## Buildpack fixes
+
+export APP_DIR="$app_dir"
+export HOME="$app_dir"
+export REQUEST_ID=$(openssl rand -base64 32)
+export STACK=cedar-14
+export CURL_CONNECT_TIMEOUT=30
+
+## Buildpack detection
+
+buildpacks=($buildpack_root/*)
+selected_buildpack=
+
+if [[ -n "$BUILDPACK_URL" ]]; then
+	echo_title "Fetching custom buildpack"
+
+	buildpack="$buildpack_root/custom"
+	rm -rf "$buildpack"
+	/tmp/builder/install-buildpack "$buildpack_root" "$BUILDPACK_URL" custom &> /dev/null
+	selected_buildpack="$buildpack"
+	buildpack_name=$($buildpack/bin/detect "$build_root") && selected_buildpack=$buildpack
+else
+  for buildpack in "${buildpacks[@]}"; do
+	buildpack_name=$($buildpack/bin/detect "$build_root") && selected_buildpack=$buildpack && break
+  done
+fi
+
+if [[ -n "$selected_buildpack" ]]; then
+	echo_title "$buildpack_name app detected"
+else
+	echo_title "Unable to select a buildpack"
+	exit 1
+fi
+
+## Buildpack compile
+
+$selected_buildpack/bin/compile "$build_root" "$cache_root" | ensure_indent
+$selected_buildpack/bin/release "$build_root" "$cache_root" > $build_root/.release
+
+## Display process types
+
+echo_title "Discovering process types"
+if [[ -f "$build_root/Procfile" ]]; then
+	types=$(ruby -e "require 'yaml';puts YAML.load_file('$build_root/Procfile').keys().join(', ')")
+	echo_normal "Procfile declares types -> $types"
+fi
+default_types=""
+if [[ -s "$build_root/.release" ]]; then
+	default_types=$(ruby -e "require 'yaml';puts (YAML.load_file('$build_root/.release')['default_process_types'] || {}).keys().join(', ')")
+	[[ $default_types ]] && echo_normal "Default process types for $buildpack_name -> $default_types"
+fi
+
+## Load profile.d and release config
+
+if [[ -s .release ]]; then
+	ruby -e "require 'yaml';(YAML.load_file('.release')['config_vars'] || {}).each{|k,v| puts \"#{k}=\${#{k}:-'#{v}'}\"}" > .profile.d/config_vars
+fi
+
+## Generate start commands
+cat > /exec <<EOF
+#!/bin/bash
+export HOME=$app_dir
+cd $app_dir
+for file in .profile.d/*; do
+	source \$file
+done
+hash -r
+"\$@"
+EOF
+
+cat > /start <<EOF
+#!/bin/bash
+export HOME=$app_dir
+cd $app_dir
+for file in .profile.d/*; do
+	source \$file
+done
+hash -r
+if [[ -f Procfile ]]; then
+  ruby -e "require 'yaml';puts YAML.load_file('Procfile')['\$1']" | bash
+else
+	ruby -e "require 'yaml';puts (YAML.load_file('.release')['default_process_types'] || {})['\$1']" | bash
+fi
+EOF
+
+## Finalize build
+chmod +x /exec
+chmod +x /start
+rm -rf $app_dir
+mv $build_root $app_dir
+
+# Clean up
+rm -rf /build/
+rm -rf /tmp/*

buildstep

@@ -1,5 +1,5 @@
 #!/bin/bash
-set -e
+set -eo pipefail
 NAME="$1"
 TAG="$2"