Securely storing environment variables in GAE with app.yaml

Question

I need to store API keys and other sensitive information in app.yaml as environment variables for deployment on GAE. The issue with this is that if I push app.yaml to GitHub, this information becomes public (not good). I don't want to store the info in a datastore as it does not suit the project. Rather, I'd like to swap out the values from a file that is listed in .gitignore on each deployment of the app.

Here is my app.yaml file:

application: myapp
version: 3 
runtime: python27
api_version: 1
threadsafe: true

libraries:
- name: webapp2
  version: latest
- name: jinja2
  version: latest

handlers:
- url: /static
  static_dir: static

- url: /.*
  script: main.application  
  login: required
  secure: always
# auth_fail_action: unauthorized

env_variables:
  CLIENT_ID: ${CLIENT_ID}
  CLIENT_SECRET: ${CLIENT_SECRET}
  ORG: ${ORG}
  ACCESS_TOKEN: ${ACCESS_TOKEN}
  SESSION_SECRET: ${SESSION_SECRET}

Any ideas?

Answer 1

This solution is simple but may not suit all different teams.

First, put the environment variables in an env_variables.yaml, e.g.,

env_variables:
  SECRET: 'my_secret'

Then, include this env_variables.yaml in the app.yaml

includes:
  - env_variables.yaml

Finally, add the env_variables.yaml to .gitignore, so that the secret variables won't exist in the repository.

In this case, the env_variables.yaml needs to be shared among the deployment managers.

Answer 2

If it's sensitive data, you should not store it in source code as it will be checked into source control. The wrong people (inside or outside your organization) may find it there. Also, your development environment probably uses different config values from your production environment. If these values are stored in code, you will have to run different code in development and production, which is messy and bad practice.

In my projects, I put config data in the datastore using this class:

from google.appengine.ext import ndb

class Settings(ndb.Model):
  name = ndb.StringProperty()
  value = ndb.StringProperty()

  @staticmethod
  def get(name):
    NOT_SET_VALUE = "NOT SET"
    retval = Settings.query(Settings.name == name).get()
    if not retval:
      retval = Settings()
      retval.name = name
      retval.value = NOT_SET_VALUE
      retval.put()
    if retval.value == NOT_SET_VALUE:
      raise Exception(('Setting %s not found in the database. A placeholder ' +
        'record has been created. Go to the Developers Console for your app ' +
        'in App Engine, look up the Settings record with name=%s and enter ' +
        'its value in that record\'s value field.') % (name, name))
    return retval.value

Your application would do this to get a value:

API_KEY = Settings.get('API_KEY')

If there is a value for that key in the datastore, you will get it. If there isn't, a placeholder record will be created and an exception will be thrown. The exception will remind you to go to the Developers Console and update the placeholder record.

I find this takes the guessing out of setting config values. If you are unsure of what config values to set, just run the code and it will tell you!

The code above uses the ndb library which uses memcache and the datastore under the hood, so it's fast.

---

Update:

jelder asked for how to find the Datastore values in the App Engine console and set them. Here is how:

1. Go to https://console.cloud.google.com/datastore/

2. Select your project at the top of the page if it's not already selected.

3. In the Kind dropdown box, select Settings.

4. If you ran the code above, your keys will show up. They will all have the value NOT SET. Click each one and set its value.

Hope this helps!

Answer 3

This didn't exist when you posted, but for anyone else who stumbles in here, Google now offers a service called Secret Manager.

It's a simple REST service (with SDKs wrapping it, of course) to store your secrets in a secure location on google cloud platform. This is a better approach than Data Store, requiring extra steps to see the stored secrets and having a finer-grained permission model -- you can secure individual secrets differently for different aspects of your project, if you need to.

It offers versioning, so you can handle password changes with relative ease, as well as a robust query and management layer enabling you to discover and create secrets at runtime, if necessary.

Python SDK

Example usage:

from google.cloud import secretmanager_v1beta1 as secretmanager

secret_id = 'my_secret_key'
project_id = 'my_project'
version = 1    # use the management tools to determine version at runtime

client = secretmanager.SecretManagerServiceClient()

secret_path = client.secret_version_path(project_id, secret_id, version)
response = client.access_secret_version(secret_path)
password_string = response.payload.data.decode('UTF-8')

# use password_string -- set up database connection, call third party service, whatever

Answer 4

My approach is to store client secrets only within the App Engine app itself. The client secrets are neither in source control nor on any local computers. This has the benefit that any App Engine collaborator can deploy code changes without having to worry about the client secrets.

I store client secrets directly in Datastore and use Memcache for improved latency accessing the secrets. The Datastore entities only need to be created once and will persist across future deploys. of course the App Engine console can be used to update these entities at any time.

There are two options to perform the one-time entity creation:

• Use the App Engine Remote API interactive shell to create the entities.
• Create an Admin only handler that will initialize the entities with dummy values. Manually invoke this admin handler, then use the App Engine console to update the entities with the production client secrets.

Answer 5

Best way to do it, is store the keys in a client_secrets.json file, and exclude that from being uploaded to git by listing it in your .gitignore file. If you have different keys for different environments, you can use app_identity api to determine what the app id is, and load appropriately.

There is a fairly comprehensive example here -> https://developers.google.com/api-client-library/python/guide/aaa_client_secrets.

Here's some example code:

# declare your app ids as globals ...
APPID_LIVE = 'awesomeapp'
APPID_DEV = 'awesomeapp-dev'
APPID_PILOT = 'awesomeapp-pilot'

# create a dictionary mapping the app_ids to the filepaths ...
client_secrets_map = {APPID_LIVE:'client_secrets_live.json',
                      APPID_DEV:'client_secrets_dev.json',
                      APPID_PILOT:'client_secrets_pilot.json'}

# get the filename based on the current app_id ...
client_secrets_filename = client_secrets_map.get(
    app_identity.get_application_id(),
    APPID_DEV # fall back to dev
    )

# use the filename to construct the flow ...
flow = flow_from_clientsecrets(filename=client_secrets_filename,
                               scope=scope,
                               redirect_uri=redirect_uri)

# or, you could load up the json file manually if you need more control ...
f = open(client_secrets_filename, 'r')
client_secrets = json.loads(f.read())
f.close()

Answer 6

This solution relies on the deprecated appcfg.py

You can use the -E command line option of appcfg.py to setup the environment variables when you deploy your app to GAE (appcfg.py update)

$ appcfg.py
...
-E NAME:VALUE, --env_variable=NAME:VALUE
                    Set an environment variable, potentially overriding an
                    env_variable value from app.yaml file (flag may be
                    repeated to set multiple variables).
...

Answer 7

Most answers are outdated. Using google cloud datastore is actually a bit different right now. https://cloud.google.com/python/getting-started/using-cloud-datastore

Here's an example:

from google.cloud import datastore
client = datastore.Client()
datastore_entity = client.get(client.key('settings', 'TWITTER_APP_KEY'))
connection_string_prod = datastore_entity.get('value')

This assumes the entity name is 'TWITTER_APP_KEY', the kind is 'settings', and 'value' is a property of the TWITTER_APP_KEY entity.

Answer 8

With github action instead of google cloud triggers (Google cloud triggers aren't able to find it's own app.yaml and manage the freaking environment variable by itself.)

Here is how to do it:

My environment : App engine, standard (not flex), Nodejs Express application, a PostgreSQL CloudSql

First the setup :

1. Create a new Google Cloud Project (or select an existing project).

2. Initialize your App Engine app with your project.

[Create a Google Cloud service account][sa] or select an existing one.

3. Add the the following Cloud IAM roles to your service account:

    App Engine Admin - allows for the creation of new App Engine apps

    Service Account User - required to deploy to App Engine as service account

    Storage Admin - allows upload of source code

    Cloud Build Editor - allows building of source code

[Download a JSON service account key][create-key] for the service account.

4. Add the following [secrets to your repository's secrets][gh-secret]:

    GCP_PROJECT: Google Cloud project ID

    GCP_SA_KEY: the downloaded service account key

The app.yaml

runtime: nodejs14
env: standard
env_variables:
  SESSION_SECRET: $SESSION_SECRET
beta_settings:
  cloud_sql_instances: SQL_INSTANCE

Then the github action

name: Build and Deploy to GKE

on: push

env:
  PROJECT_ID: ${{ secrets.GKE_PROJECT }}
  DATABASE_URL: ${{ secrets.DATABASE_URL}}
jobs:
  setup-build-publish-deploy:
    name: Setup, Build, Publish, and Deploy
    runs-on: ubuntu-latest

steps:
 - uses: actions/checkout@v2
 - uses: actions/setup-node@v2
   with:
    node-version: '12'
 - run: npm install
 - uses: actions/checkout@v1
 - uses: ikuanyshbekov/app-yaml-env-compiler@v1.0
   env:
    SESSION_SECRET: ${{ secrets.SESSION_SECRET }}  
 - shell: bash
   run: |
        sed -i 's/SQL_INSTANCE/'${{secrets.DATABASE_URL}}'/g' app.yaml
 - uses: actions-hub/gcloud@master
   env:
    PROJECT_ID: ${{ secrets.GKE_PROJECT }}
    APPLICATION_CREDENTIALS: ${{ secrets.GCLOUD_AUTH }}
    CLOUDSDK_CORE_DISABLE_PROMPTS: 1
   with:
    args: app deploy app.yaml

To add secrets into github action you must go to : Settings/secrets

Take note that I could handle all the substitution with the bash script. So I would not depend on the github project "ikuanyshbekov/app-yaml-env-compiler@v1.0"

It's a shame that GAE doesn't offer an easiest way to handle environment variable for the app.yaml. I don't want to use KMS since I need to update the beta-settings/cloud sql instance.. I really needed to substitute everything into the app.yaml.

This way I can make a specific action for the right environment and manage the secrets.

Answer 9

It sounds like you can do a few approaches. We have a similar issue and do the following (adapted to your use-case):

• Create a file that stores any dynamic app.yaml values and place it on a secure server in your build environment. If you are really paranoid, you can asymmetrically encrypt the values. You can even keep this in a private repo if you need version control/dynamic pulling, or just use a shells script to copy it/pull it from the appropriate place.
• Pull from git during the deployment script
• After the git pull, modify the app.yaml by reading and writing it in pure python using a yaml library

The easiest way to do this is to use a continuous integration server such as Hudson, Bamboo, or Jenkins. Simply add some plug-in, script step, or workflow that does all the above items I mentioned. You can pass in environment variables that are configured in Bamboo itself for example.

In summary, just push in the values during your build process in an environment you only have access to. If you aren't already automating your builds, you should be.

Another option option is what you said, put it in the database. If your reason for not doing that is that things are too slow, simply push the values into memcache as a 2nd layer cache, and pin the values to the instances as a first-layer cache. If the values can change and you need to update the instances without rebooting them, just keep a hash you can check to know when they change or trigger it somehow when something you do changes the values. That should be it.

Answer 10

Just wanted to note how I solved this problem in javascript/nodejs. For local development I used the 'dotenv' npm package which loads environment variables from a .env file into process.env. When I started using GAE I learned that environment variables need to be set in a 'app.yaml' file. Well, I didn't want to use 'dotenv' for local development and 'app.yaml' for GAE (and duplicate my environment variables between the two files), so I wrote a little script that loads app.yaml environment variables into process.env, for local development. Hope this helps someone:

yaml_env.js:

(function () {
    const yaml = require('js-yaml');
    const fs = require('fs');
    const isObject = require('lodash.isobject')

    var doc = yaml.safeLoad(
        fs.readFileSync('app.yaml', 'utf8'), 
        { json: true }
    );

    // The .env file will take precedence over the settings the app.yaml file
    // which allows me to override stuff in app.yaml (the database connection string (DATABASE_URL), for example)
    // This is optional of course. If you don't use dotenv then remove this line:
    require('dotenv/config');

    if(isObject(doc) && isObject(doc.env_variables)) {
        Object.keys(doc.env_variables).forEach(function (key) {
            // Dont set environment with the yaml file value if it's already set
            process.env[key] = process.env[key] || doc.env_variables[key]
        })
    }
})()

Now include this file as early as possible in your code, and you're done:

require('../yaml_env')

Answer 11

You should encrypt the variables with google kms and embed it in your source code. (https://cloud.google.com/kms/)

echo -n the-twitter-app-key | gcloud kms encrypt \
> --project my-project \
> --location us-central1 \
> --keyring THEKEYRING \
> --key THECRYPTOKEY \
> --plaintext-file - \
> --ciphertext-file - \
> | base64

put the scrambled (encrypted and base64 encoded) value into your environment variable (in yaml file).

Some pythonish code to get you started on decrypting.

kms_client = kms_v1.KeyManagementServiceClient()
name = kms_client.crypto_key_path_path("project", "global", "THEKEYRING", "THECRYPTOKEY")

twitter_app_key = kms_client.decrypt(name, base64.b64decode(os.environ.get("TWITTER_APP_KEY"))).plaintext

Answer 12

@Jason F's answer based on using Google Datastore is close, but the code is a bit outdated based on the sample usage on the library docs. Here's the snippet that worked for me:

from google.cloud import datastore

client = datastore.Client('<your project id>')
key = client.key('<kind e.g settings>', '<entity name>') # note: entity name not property
# get by key for this entity
result = client.get(key)
print(result) # prints all the properties ( a dict). index a specific value like result['MY_SECRET_KEY'])

Partly inspired by this Medium post

Answer 13

My solution is to replace the secrets in the app.yaml file via github action and github secrets.

app.yaml (App Engine)

env_variables:
  SECRET_ONE: $SECRET_ONE
  ANOTHER_SECRET: $ANOTHER_SECRET

workflow.yaml (Github)

steps:
  - uses: actions/checkout@v2
  - uses: 73h/gae-app-yaml-replace-env-variables@v0.1
    env:
      SECRET_ONE: ${{ secrets.SECRET_ONE }}
      ANOTHER_SECRET: ${{ secrets.ANOTHER_SECRET }}

Here you can find the Github action.
https://github.com/73h/gae-app-yaml-replace-env-variables

When developing locally, I write the secrets to an .env file.

Answer 14

Extending Martin's answer

from google.appengine.ext import ndb

class Settings(ndb.Model):
    """
    Get sensitive data setting from DataStore.

    key:String -> value:String
    key:String -> Exception

    Thanks to: Martin Omander @ Stackoverflow
    https://stackoverflow.com/a/35261091/1463812
    """
    name = ndb.StringProperty()
    value = ndb.StringProperty()

    @staticmethod
    def get(name):
        retval = Settings.query(Settings.name == name).get()
        if not retval:
            raise Exception(('Setting %s not found in the database. A placeholder ' +
                             'record has been created. Go to the Developers Console for your app ' +
                             'in App Engine, look up the Settings record with name=%s and enter ' +
                             'its value in that record\'s value field.') % (name, name))
        return retval.value

    @staticmethod
    def set(name, value):
        exists = Settings.query(Settings.name == name).get()
        if not exists:
            s = Settings(name=name, value=value)
            s.put()
        else:
            exists.value = value
            exists.put()

        return True

Answer 15

There is a pypi package called gae_env that allows you to save appengine environment variables in Cloud Datastore. Under the hood, it also uses Memcache so its fast

Usage:

import gae_env

API_KEY = gae_env.get('API_KEY')

If there is a value for that key in the datastore, it will be returned. If there isn't, a placeholder record __NOT_SET__ will be created and a ValueNotSetError will be thrown. The exception will remind you to go to the Developers Console and update the placeholder record.

---

Similar to Martin's answer, here is how to update the value for the key in Datastore:

1. Go to Datastore Section in the developers console

2. Select your project at the top of the page if it's not already selected.

3. In the Kind dropdown box, select GaeEnvSettings.

4. Keys for which an exception was raised will have value __NOT_SET__.

---

Go to the package's GitHub page for more info on usage/configuration