Some Configuration variables are read by Aptible itself (they're still exposed to your App Containers as environment variables).

Here is the list:

FORCE_SSL

See HTTPS Redirect.

STRICT_HEALTH_CHECKS

See Strict Health Checks.

IDLE_TIMEOUT

See Endpoint Timeouts.

SSL_PROTOCOLS_OVERRIDE

See HTTPS Protocols.

SSL_CIPHERS_OVERRIDE

See HTTPS Protocols.

DISABLE_WEAK_CIPHER_SUITES

See HTTPS Protocols.

SHOW_ELB_HEALTHCHECKS

See Endpoint configuration variables

RELEASE_HEALTHCHECK_TIMEOUT

See Release Health Checks.

MAINTENANCE_PAGE_URL

See Maintenance Page.

APTIBLE_PRIVATE_REGISTRY_USERNAME

This variable is usually set using the --private-registry-username flag on aptible deploy.

See Private Registry Authentication for more details.

APTIBLE_PRIVATE_REGISTRY_PASSWORD

This variable is usually set using the --private-registry-password flag on aptible deploy.

See Private Registry Authentication for more details.

APTIBLE_DO_NOT_WIPE

See Disabling filesystem wipes.