These variables must be defined, except where otherwise noted.
S3 connection parameters:
S3_HOSTS3_ACCESS_KEYS3_SECRET_KEY
S3 storage location:
BUCKET_NAMEOBJECT_PREFIX: Should not end with a/.
Postgres connection parameters:
PG_HOSTPG_PORTPG_USERPG_PASSWORDPG_DATABASE
Other configuration:
PG_DUMP_OPTIONS: Optional. May contain additional command-line flags to pass topg_dump.