Added simple readme and changelog for error queue cleanup script.

Author: lmarini

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Added
+- Error queue cleanup script
+
 ## 1.10.1 - 2020-07-16
 
 ### Fixed

scripts/rmq-error-shovel/README.md

@@ -0,0 +1,19 @@
+Error queue cleanup up script
+=============================
+
+Script to remove files from an error queue if a message refers to a file that doesn't exist anymore. Otherwise moves the
+message to the appropriate queue for reprocessing.
+
+This should be executed when needed and not on a timer in case there are other types of error that would result in an
+endless loop of messages going from execution queue to error queue and back to execution queue.
+
+To build the container run `docker build -t clowder/rmq-error-shovel .`
+
+To run the container on the a specific queue, for example `ncsa.image.preview` run this command (use your api key and 
+change other parameters as needed):
+
+```
+docker run -t --rm --net=host -e EXTRACTOR_QUEUE=ncsa.image.preview -e CLOWDER_HOST=http://host.docker.internal:9000 
+-e CLOWDER_KEY=your_api_key -e RABBITMQ_URI="amqp://guest:[email protected]:5672/%2f" 
+clowder/rmq-error-shovel
+```