A simple extension to environ that polls a DynamoDB table for configuration overrides.

You config environ-dynamo via environ itself; the following environ keys are used:

• :environ-dynamo-access-key Your AWS access key.
• :environ-dynamo-secret-key Your AWS secret key.
• :environ-dynamo-endpoint The AWS endpoint to use (may also be used to specify the AWS region).
• :environ-dynamo-profile The credential profile to use, in lieu of access/secret keys.
• :environ-dynamo-table-name The name of the table to scan. The default is "environProperties".
• :environ-dynamo-poll-interval The interval between polls, in milliseconds. The default is 60000.
• :environ-dynamo-poll-limit The number of entries to scan in each poll. Default is 100. If this is zero or negative, then polling is not done (but the table is read at least once).

The DynamoDB table must contain at least two fields: key and value. The key field is taken as the key, and is massaged into a keyword the same way environ does: lowercased, with _ or . replaced by -; the key field should also be the partition key of the table. The value field should contain strings.

(ns example
  (:require [environ.dynamo :as env]))
  
;;; Starts polling DynamoDB.
(env/start-polling!)

;;; Results from DynamoDB are merged with environ.core/env
(:some-config (env/env))

;;; You can stop polling too.
(env/stop-polling!)

Inspired by archaius.