If you set this environment variable value to `https://acme-staging-v02.api.letsencrypt.org/directory` the container will obtain its certificates from Let's Encrypt test API endpoint that don't have the [5 certs/week/domain limit](https://letsencrypt.org/docs/rate-limits/) (but are not trusted by browsers).
*`DEBUG` - Set it to `1` to enable debugging of the entrypoint script and generation of LetsEncrypt certificates, which could help you pin point any configuration issues.
*`RENEW_PRIVATE_KEYS` - Set it to `false` to make `acme.sh` reuse previously generated private key for each certificate instead of creating a new one on certificate renewal. Reusing private keys can help if you intend to use [HPKP](https://developer.mozilla.org/en-US/docs/Web/HTTP/Public_Key_Pinning), but please note that HPKP has been deprecated by Google's Chrome and that it is therefore strongly discouraged to use it at all.
*`DHPARAM_BITS` - Change the size of the Diffie-Hellman key generated by the container from the default value of 2048 bits. For example `--env DHPARAM_BITS=1024` to support some older clients like Java 6 and 7.
*`CA_BUNDLE` - This is a test only variable [for use with Pebble](https://github.com/letsencrypt/pebble#avoiding-client-https-errors). It changes the trusted root CA used by `acme.sh`, from the default Alpine trust store to the CA bundle file located at the provided path (inside the container). Do **not** use it in production unless you are running your own ACME CA.
*`CERTS_UPDATE_INTERVAL` - 1 hour by default, this defines how often the container will check if the certificates require update.
