How to use Google API credentials json on Heroku?

Question

I\'m making an app using Google Calendar API, and planning to build it on Heroku.
I have a problem about authentication. Usually I use credential json file for that, but

Answer 1

I have done this like below:

• Created two env variable
  1. CREDENTIALS - base64 encoded value of google api credential
  2. CONFIG_FILE_PATH - /app/.gcp/key.json (this file we will create it at run time. in heroku preinstall phase as below)

Create a preinstall script.

"heroku-prebuild": "bash preinstall.sh",

And in preinstall.sh file, decode CREDENTIALS and create a config file and update it there.

if [ "$CREDENTIALS" != "" ]; then


echo "Detected credentials. Adding credentials" >&1
  echo "" >&1

  # Ensure we have an gcp folder
  if [ ! -d ./.gcp ]; then
    mkdir -p ./.gcp
    chmod 700 ./.gcp
  fi

  # Load the private key into a file.
  echo $GCP_CREDENTIALS | base64 --decode > ./.gcp/key.json

  # Change the permissions on the file to
  # be read-only for this user.
  chmod 400 ./.gcp/key.json
fi