How do I put Firebase-Admin credentials in an Environment Variable? - firebase

Question

I'm trying to setup a Firebase project on Codeship CI/CD and I cannot seem to get the service credentials JSON key to work with my project when it's stored in an environment variable.
MVCE
Dev environment startup script
export FIREBASE_CREDENTIAL=BASE64ENCODED_credentials_json
export DATABASE_URL=https://my-project.firebaseio.com
echo $FIREBASE_CREDENTIAL | base64 -D > FIREBASE_CREDENTIAL.json
npm start
index.ts
import * as admin from "firebase-admin";
const credentials = require("../FIREBASE_CREDENTIAL.json");
const databaseURL = process.env.DATABASE_URL;
console.log(credentials.project_id); // succeeds
console.log(databaseURL); // is correct
admin.initializeApp({
...credentials,
databaseURL,
databaseAuthVariableOverride: { uid: "scraper" }
});
admin
.database()
.ref("/test")
.set(admin.database.ServerValue.TIMESTAMP);
Codeship script
echo $FIREBASE_CREDENTIAL | base64 -di > FIREBASE_CREDENTIAL.json
nvm install 8
npm install
npm test
Results
On dev machine, the write succeeds as expected
On Codeship CI container, I get this error.
console.warn node_modules/#firebase/logger/dist/index.cjs.js:66
[2018-10-05T12:53:51.316Z] #firebase/database: FIREBASE WARNING: {"code":"app/invalid-credential","message":"Credential implementation provided to initializeApp() via the \"credential\" property failed to fetch a valid Google OAuth2 access token with the following error: \"Failed to parse access token response: Error: Error while making request: getaddrinfo ENOTFOUND metadata.google.internal metadata.google.internal:80. Error code: ENOTFOUND\"."}