Buildpack compile fixes and refactoring

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+* [#177](https://github.com/heroku/heroku-buildpack-static/pull/177) Make curl retry in case of a failed download
+* [#177](https://github.com/heroku/heroku-buildpack-static/pull/177) Fix the printing of the installed nginx version
+* [#177](https://github.com/heroku/heroku-buildpack-static/pull/177) Switch to the recommended S3 URL format
+* [#177](https://github.com/heroku/heroku-buildpack-static/pull/177) Remove unused archive caching
+* [#177](https://github.com/heroku/heroku-buildpack-static/pull/177) Fail the build early on unsupported stacks
 
 ## v4 (2019-09-18)
 

bin/compile

@@ -1,36 +1,32 @@
 #!/usr/bin/env bash
 # bin/compile <build-dir> <cache-dir> <env-dir>
 
-set -e
+set -euo pipefail
 
 build_dir=$1
 cache_dir=$2
 env_dir=$3
 bp_dir=$(dirname $(dirname $0))
 
-fetch_nginx_tarball() {
-    local version="1.9.7"
-    local tarball_file="nginx-$version.tgz"
-    local stack="cedar-14"
-    local nginx_tarball_url="https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/nginx/$stack/nginx-$version-ngx_mruby.tgz"
-    local dest_path="$cache_dir/$stack/$tarball_file"
-
-    if [ -f "$dest_path" ]; then
-        echo -n "cat $dest_path"
-    else
-        echo -n "curl -L $nginx_tarball_url"
-    fi
-}
+case "${STACK}" in
+  cedar-14|heroku-16|heroku-18)
+    # The buildpack for some time has used binaries meant for Cedar-14 on all stacks (see #165).
+    # In the future these stacks should be migrated to newer nginx built against the correct stack.
+    nginx_archive_url='https://heroku-buildpack-ruby.s3.amazonaws.com/nginx/cedar-14/nginx-1.9.7-ngx_mruby.tgz'
+    ;;
+  *)
+    echo "Stack ${STACK} is not supported!"
+    exit 1
+    ;;
+esac
 
 mkdir -p $build_dir/bin
-$(fetch_nginx_tarball) | tar xzC $build_dir/bin
-nginx_version=$($build_dir/bin/nginx-$STACK -V 2>&1 | head -1 | awk '{ print $NF }')
+curl -sSf --retry 3 --connect-timeout 3 "${nginx_archive_url}" | tar -xzC "${build_dir}/bin"
+nginx_version=$("${build_dir}/bin/nginx" -v |& cut -d '/' -f 2-)
 cp -a $bp_dir/scripts/{boot,config} -t $build_dir/bin/
-echo "-----> Installed ${nginx_version} to /app/bin"
+echo "-----> Installed nginx ${nginx_version} to /app/bin"
 
 mkdir -p $build_dir/config
 cp $bp_dir/scripts/config/templates/mime.types $build_dir/config
 
 mkdir -p $build_dir/logs
-
-exit 0