probot/docs/configuration.md

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docs/deployment.md

Environment configuration

When developing a Probot App, you will need to have several different fields in a .env file which specify environment variables. Here are some common use cases:

Variable	Description
APP_ID	The App ID assigned to your GitHub App. Required (Example: 1234)
Private key options	One of the following is Required if there is no .pem file in your project's root directory
PRIVATE_KEY_PATH	The path to the .pem file for your GitHub App. (Example: path/to/key.pem)
PRIVATE_KEY	The contents of the private key for your GitHub App. If you're unable to use multiline environment variables, use base64 encoding to convert the key to a single line string. See the Deployment docs for provider specific usage.
Webhook options
WEBHOOK_PROXY_URL	Allows your local development environment to receive GitHub webhook events. Go to https://smee.io/new to get started. (Example: https://smee.io/your-custom-url)
WEBHOOK_SECRET	The webhook secret used when creating a GitHub App. 'development' is used as a default, but the value in .env needs to match the value configured in your App settings on GitHub. Note: GitHub marks this value as optional, but for optimal security it's required for Probot apps. Required (Example: development)

For more on the set up of these items, check out Configuring a GitHub App.

Some less common environment variables are:

Variable	Description
DISABLE_STATS	Set to true to disable the the /probot/stats endpoint, which gathers data about each app. Recommend for apps with a lot of installations. (Example: true)
GHE_HOST	The hostname of your GitHub Enterprise instance. (Example: github.mycompany.com)
IGNORED_ACCOUNTS	A comma-separated list of GitHub account names to ignore. This is currently used by the /probot/stats. By marking an account as ignored, that account will not be included in data collected on the website. The primary use case for this is spammy or abusive users that the GitHub API sends us but who 404. (Example: spammyPerson,abusiveAccount)
LOG_FORMAT	By default, logs are formatted for readability in development. You can set this to short, long, simple, json, bunyan. Default: short
LOG_LEVEL	The verbosity of logs to show when running your app, which can be trace, debug, info, warn, error, or fatal. Default: info
PORT	The port to start the local server on. Default: 3000.
SENTRY_DSN	Set to a Sentry DSN to report all errors thrown by your app. (Example: https://1234abcd@sentry.io/12345)
WEBHOOK_PATH	The URL path which will receive webhooks. Default: /.
INSTALLATION_TOKEN_TTL	The length of time installation access tokens are cached by Probot. This may be useful if your app is running long processes before accessing context.github. Default: 3540 (59 minutes) (Example: 3300 or 55 minutes)
REDIS_URL	Set to a redis:// url as connection option for ioredis in order to enable cluster support for request throttling. (Example: redis://:secret@redis-123.redislabs.com:12345/0)

For more information on the formatting conventions and rules of .env files, check out the npm dotenv module's documentation.