Add support for installing dependencies through yarn (#55)

Function dependencies are now installed using yarn when yarn.lock is
present in the application source code.

Author: lukasberger

converter/Dockerfile

@@ -1,6 +1,6 @@
 FROM gcr.io/gcp-runtimes/ubuntu_18_0_4
 
-COPY convert .npmrc /converter/
+COPY convert install-function-dependencies .npmrc /converter/
 
 COPY without-package /converter/without-package
 COPY with-package-without-framework /converter/with-package-without-framework

converter/convert

@@ -18,11 +18,13 @@ if [[ ! -f functions/package.json ]]; then
   echo 'Handling functions without package.json'
   cp /converter/without-package/package.json .
   cp /converter/without-package/package-lock.json .
+  cp /converter/install-function-dependencies .
   ln -s node_modules/.bin/functions-framework start-functions-framework
 elif ! cat functions/package.json | jq -e ".dependencies.\"@google-cloud/functions-framework\""; then
   echo 'Handling functions with package.json without dependency on @google-cloud/functions-framework'
   cp /converter/with-package-without-framework/package.json .
   cp /converter/with-package-without-framework/package-lock.json .
+  cp /converter/install-function-dependencies .
   ln -s node_modules/.bin/functions-framework start-functions-framework
 else
   echo 'Handling functions with package.json with dependency on functions-framework'

converter/install-function-dependencies

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# Installs dependencies specified by the function.
+
+set -euo pipefail
+
+echo 'Installing function dependencies'
+
+if [[ -f functions/yarn.lock ]]; then
+  echo 'Found yarn.lock; using yarn'
+  yarn install --cwd functions
+else
+  npm install --prefix functions
+fi
+
+echo 'Installing function dependencies done'

converter/with-package-with-framework/package.json

@@ -1,6 +1,6 @@
 {
   "scripts": {
-    "preinstall": "npm --prefix functions install",
+    "preinstall": "./install-function-dependencies",
     "start": "cd functions && node_modules/.bin/functions-framework"
   }
 }

converter/with-package-without-framework/package.json

@@ -3,7 +3,7 @@
     "@google-cloud/functions-framework": "^1.0.0"
   },
   "scripts": {
-    "preinstall": "npm --prefix functions install",
+    "preinstall": "./install-function-dependencies",
     "start": "cd functions && functions-framework"
   }
 }