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Let's Encrypt integration

Cloudron integrates with Let's Encrypt to install and renew TLS certificates for apps automatically.

Cloudron utilizes the http-01 scheme to validate the domain with Lets Encrypt (this scheme involves provisioning an HTTP resource under a well-known URI). For this reason, the server's incoming port 80 must be kept open.

LE has a rate limit of ~20 new issuances per week per top level domain (renewals are not counted as part of this limit). This limit means that you can install atmost 20 apps in a week across all your Cloudron instances.

We recommend purchasing a wildcard certificate if you hit those limits. GarrisonHost provides them for 45 USD. Once purchased, it can be set as the fallback certificate in the Certificate UI. Let's Encrypt recently announced that they will start issuing wildcard certificates from Jan 2018, so this is expected to be a temporary workaround.

Automatic renewal of Let's Encrypt certificates

Cloudron attempts to start renewing certificates automatically 1 month before expiry of the certificate. If renewal fails, a notification email will be sent to the Cloudron administrators. If the Cloudron admin does not take any action (after getting reminded 30 times), Cloudron will start using fallback certificates for the app.

Setting fallback wildcard certificate

Cloudron generates a self-signed certificate that is used as the fallback should it fail to install or renew Let's Encrypt certificate. The auto-generated fallback certificate can be replaced with a custom wildcard certificate in the Domains & Certs page.

Manually renewing Let's Encrypt certificate

To manually trigger re-installation or renewal of Let's encrypt certificate, open the app's configure dialog and Save without making any changes.

Revokation of Let's Encrypt Certificate

Cloudron does not revoke certificates when an app is uninstalled. Instead, it retains the certificate, so that it can be reused if another app is installed in the same subdomain. This allows you to install apps for testing in the same location, say test, and not have to worry about running over the Let's Encrypt rate limit.

Limitations of Let's Encrypt

When using Let's Encrypt, please be aware of the following:

  • There is a rate limit of 20 certificates for a domain per week.

  • Let's Encrypt participates in Certificate transparency. This means that your apps and subdomains are discoverable via the Certificate transparency project ( and Google's website) Some hackers take advantage of this to hack web applications before they are in installed.

Setting custom certificates

Custom certificates can be set for each installed application using the REST API. This can be used to set an Extended Validation (EV) certificate for an app.

To set a custom wildcard certificate to be used across all the apps, pass the --tls-provider fallback option at installation time to the cloudron-setup script and set it as a fallback certificate.

Common reasons for Let's Encrypt Certificate failure

Here are some of the common reasons why the Cloudron might fail to get certificates via Let's Encrypt.

  • The Cloudron administrator email is not valid. Let's Encrypt requires a valid email id for issuing certificates. Please check the email id in the Account page.

  • Let's Encrypt requires incoming port 80 to be accepted from all IPs. Note that Cloudron enforces port 443/HTTPS for all communication and any request on port 80 is redirected to HTTPS. For this reason, it is safe to keep port 80 completely open. Port 433/HTTPS can be restricted to specific IPs safely.

  • Let's Encrypt rate limit was reached.

CAA records for Lets Encrypt

Starting Sep 2017, Lets Encrypt will check for CAA records to validate if the domain owner has authorized the CA to issue certificates for the domain. For this reason, make sure that either the CAA record for the domain is empty OR setup a CAA record allowing