Added instructions for log control and upgrade

docker/Readme.md

@@ -51,17 +51,22 @@ You can retrieve the container IP address with `docker inspect`.
 
 #### Easier to handle
 
-	docker run --name yacy -p 8090:8090 luccioman/yacy
+	docker run --name yacy -p 8090:8090 --log-opt max-size=100m --log-opt max-file=2 luccioman/yacy
 	
---name option allow easier management of your container (without it, docker automatically generate a new name at each startup).
+##### Options detail
 	
--p option map host port and container port, allowing web interface access through the usual http://localhost:8090.
+* --name : allow easier management of your container (without it, docker automatically generate a new name at each startup).
+* -p : map host port and container port, allowing web interface access through the usual http://localhost:8090.
+* --log-opt max-size : limit maximum docker log file size for this container
+* --log-opt max-file : limit number of docker rotated log files for this container
+
+Note : if you do not specify the log related options, when running a YaCy container 24hour a day with default log level, your Docker container log file will grow up to some giga bytes in a few days!
 
 #### Handle persistent data volume
 
 As configured in the Dockerfile, by default yacy data (in /opt/yacy_search_server/DATA) will persist after container stop or deletion, in a volume with an automatically generated id.
 
-Bu you may map a host directory to hold yacy data in container :
+But you may map a host directory to hold yacy data in container :
 
 	docker run -v [/your_host/data/directory]:/opt/yacy_search_server/DATA luccioman/yacy
 	
@@ -94,6 +99,37 @@ Note that you can list all docker volumes with :
 
 	docker exec [your_container_name] /opt/yacy_search_server/stopYACY.sh
 	
+### Upgrade
+
+You can upgrade your YaCy container the Docker way with the following commands sequence.
+
+Get latest Docker image :
+
+	docker pull luccioman/yacy:latest
+OR 
+	docker pull luccioman/yacy:latest-alpine
+	
+Create new container based on pulled image, using volume data from old container :
+	
+	docker create --name [tmp-container_name] -p 8090:8090 --volumes-from=[container_name] luccioman/yacy:latest
+	
+Stop old container :
+
+	docker exec [container_name] /opt/yacy_search_server/stopYACY.sh
+	
+
+Start new container :
+
+	docker start [tmp-container_name]
+	
+Check everything works fine, then you can delete old container :
+	
+	docker rm [container_name]
+	
+Rename new container to reuse same container name :
+
+	docker rename [tmp-container_name] [container_name]
+
 ## License
 
 View [license](https://github.com/yacy/yacy_search_server/blob/master/COPYRIGHT) information for the software contained in this image.