Aleff is configured through environment variables.


Set this to disabled to prevent aleff from obtaining certificates for all domains by default.

Default: enabled

When set to enabled you can disable aleff for a service by adding the tag aleff-disabled.

When set to disabled you can enable aleff for a service by adding the tag aleff-enabled.


Specify an email address at which you want to receive expiration notifications in case Aleff fails to renew a certificate. As of writing this documentation they do this 20 days before expiry giving you plenty of time to diagnose and fix the problem.

While Let's Encrypt allows certificates to be requested without an email address Aleff requires one to ensure you are aware if renewal is failing.

Default: none (required)


This is the filename of the aleff-challenge-responder service job definition.

Default: none (required)


This variable defines how frequently Aleff should check for new domains and domains to renew. Valid intervals consist of a positive number followed by a units suffix. Valid units are h, m and s.

Examples: * 5m * 1h * 1h30m * 24h

If this variable is set to 0 Aleff will run once and exit.

Default: 0


This variable defines how long before expiry a certificate will be renewed. It has the same syntax as RUN_INTERVAL. Note that the default is based on Let's Encrypt recommendations.

Default: 696h (29 days)


Set this to any non-empty value to disable launching the challenge responder job as part of obtaining a certificate. Use this if you're permanently running the challenge responder.

Default: "" (empty string)


Specifies how long aleff will wait for the challenge responder job to start responding correctly to the challenge request. Uses the same duration semantics as RUN_INTERVAL.

Default: 1m (1 minute)


If you're using a non-standard prefix for Fabio routing tags, specify it here.

Default: urlprefix-

Consul KeyValue keys

Aleff stores everything it needs in Consul and the location of this data can be modified through several environment variables.

See the Consul Layout page for details.