ci: vercel build

Author: robot

package.json

@@ -12,7 +12,8 @@
     "test": "echo \"Error: no test specified\" && exit 1",
     "daily-schedule": "node ./schedule/daily-problem.js && node ./schedule/daily-check.js && node ./schedule/check-in.js",
     "generate": "node ./static/solution/generate.js && node ./static/users/generate.js",
-    "lecture": "node ./static/lectures/generate.js"
+    "lecture": "node ./static/lectures/generate.js",
+    "vercel-install": "./vercel-submodule-workaround.sh && yarn --ignore-scripts --production=false"
   },
   "dependencies": {
     "@koa/cors": "^3.1.0",
@@ -35,4 +36,4 @@
   "devDependencies": {
     "nodemon": "^1.19.1"
   }
-}
+}

vercel-submodule-workaround.sh

@@ -0,0 +1,39 @@
+# github submodule repo address without https:// prefix
+SUBMODULE_GITHUB=github.com/beeinger/vercel-private-submodule
+
+# .gitmodules submodule path
+SUBMODULE_PATH=library
+
+# github access token is necessary
+# add it to Environment Variables on Vercel
+if [ "$GITHUB_ACCESS_TOKEN" == "" ]; then
+  echo "Error: GITHUB_ACCESS_TOKEN is empty"
+  exit 1
+fi
+
+# stop execution on error - don't let it build if something goes wrong
+set -e
+
+# get submodule commit
+output=`git submodule status --recursive` # get submodule info
+no_prefix=${output#*-} # get rid of the prefix
+COMMIT=${no_prefix% *} # get rid of the suffix
+
+# set up an empty temporary work directory
+rm -rf tmp || true # remove the tmp folder if exists
+mkdir tmp # create the tmp folder
+cd tmp # go into the tmp folder
+
+# checkout the current submodule commit
+git init # initialise empty repo
+git remote add origin https://$GITHUB_ACCESS_TOKEN@$SUBMODULE_GITHUB # add origin of the submodule
+git fetch --depth=1 origin $COMMIT # fetch only the required version
+git checkout $COMMIT # checkout on the right commit
+
+# move the submodule from tmp to the submodule path
+cd .. # go folder up
+rm -rf tmp/.git # remove .git 
+mv tmp/* $SUBMODULE_PATH/ # move the submodule to the submodule path
+
+# clean up
+rm -rf tmp # remove the tmp folder