## Optional container environment variables for custom configuration.

* `ACME_CA_URI` - Directory URI for the CA ACME API endpoint (defaults to ``https://acme-v02.api.letsencrypt.org/directory``).

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).

For example

```bash
$ docker run --detach \
    --name nginx-proxy-acme \
    --volumes-from nginx-proxy \
    --volume /var/run/docker.sock:/var/run/docker.sock:ro \
    --volume certs:/etc/nginx/certs:rw \
    --volume acme:/etc/acme.sh \
    --env "ACME_CA_URI=https://acme-staging-v02.api.letsencrypt.org/directory" \
    nginxproxy/acme-companion
```
You can also create test certificates per container (see [Test certificates](./Let's-Encrypt-and-ACME.md#test-certificates))

* `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` - 3600 seconds by default, this defines how often the container will check if the certificates require update.