Link Solr Operator for learning on Solr in Kubernetes, and better exp… (#1114)

* Remove docker-networking.adoc page
* Write a few paragraphs about cloud in the FAQ
* Remove bad advice about docker links
* Remove info about legacy v5-7
* Add example of compose file for cloud

Co-authored-by: Jan Høydahl <[email protected]>

Author: jebnix

dev-docs/running-in-docker.adoc

@@ -1,4 +1,4 @@
-# Running Solr in Docker
+= Running Solr in Docker
 
 You can run Solr in Docker via the https://hub.docker.com/_/solr[official image].
 
@@ -11,7 +11,7 @@ In order to start Solr in cloud mode, run the following.
 `docker run -p 8983:8983 solr solr-fg -c`
 
 For documentation on using the official docker builds, please refer to the https://hub.docker.com/_/solr[DockerHub page].
-Up to date documentation for running locally built images of this branch can be found in the xref:_running_solr_in_docker[local reference guide].
+Up-to-date documentation for running locally built images of this branch can be found in the xref:_running_solr_in_docker[local reference guide].
 
 There is also a gradle task for building custom Solr images from your local checkout.
 These local images are built identically to the official image except for retrieving the Solr artifacts locally instead of from the official release.
@@ -29,5 +29,5 @@ For more info on building an image, run:
 
 `./gradlew helpDocker`
 
-## Additional Information
+== Additional Information
 You can find additional information in the https://solr.apache.org/guide/solr/latest/deployment-guide/solr-in-docker.html[Solr Ref Guide Docker Page]

solr/solr-ref-guide/modules/deployment-guide/deployment-nav.adoc

@@ -29,7 +29,6 @@
 ** xref:backup-restore.adoc[]
 ** xref:solr-in-docker.adoc[]
 *** xref:docker-faq.adoc[]
-*** xref:docker-networking.adoc[]
 ** xref:solr-on-hdfs.adoc[]
 
 * Scaling Solr

solr/solr-ref-guide/modules/deployment-guide/pages/docker-faq.adoc

@@ -49,30 +49,17 @@ docker run --rm -p 8983:8983 -v solrData:/mysolrhome solr:9-slim
 
 == Can I run ZooKeeper and Solr clusters under Docker?
 
-At the network level the ZooKeeper nodes need to be able to talk to each other,
-and the Solr nodes need to be able to talk to the ZooKeeper nodes and to each other.
-At the application level, different nodes need to be able to identify and locate each other.
-In ZooKeeper that is done with a configuration file that lists hostnames or IP addresses for each node.
-In Solr that is done with a parameter that specifies a host or IP address, which is then stored in ZooKeeper.
-
-In typical clusters, those hostnames/IP addresses are pre-defined and remain static through the lifetime of the cluster.
-In Docker, inter-container communication and multi-host networking can be facilitated by https://docs.docker.com/engine/userguide/networking/[Docker Networks].
-But, crucially, Docker does not normally guarantee that IP addresses of containers remain static during the lifetime of a container.
-In non-networked Docker, the IP address seems to change every time you stop/start.
-In a networked Docker, containers can lose their IP address in certain sequences of starting/stopping, unless you take steps to prevent that.
-
-IP changes cause problems:
-
-* If you use hardcoded IP addresses in configuration, and the addresses of your containers change after a stops/start, then your cluster will stop working and may corrupt itself.
-* If you use hostnames in configuration, and the addresses of your containers change, then you might run into problems with cached hostname lookups.
-* And if you use hostnames there is another problem: the names are not defined until the respective container is running,
-So when for example the first ZooKeeper node starts up, it will attempt a hostname lookup for the other nodes, and that will fail.
-This is especially a problem for ZooKeeper 3.4.6; future versions are better at recovering.
-
-Docker 1.10 has a new `--ip` configuration option that allows you to specify an IP address for a container.
-It also has a `--ip-range` option that allows you to specify the range that other containers get addresses from.
-Used together, you can implement static addresses.
-See the xref:docker-networking.adoc[] for more information.
+Yes. You can simply start your Solr containers in "Cloud mode", pointing
+them to a xref:zookeeper-ensemble.adoc[Zookeeper Ensemble].
+
+For local development, using a single zookeeper container is enough.
+Please consult the https://hub.docker.com/_/zookeeper[Zookeeper docker image] for details.
+
+For production purposes, we discourage rolling your own Zookeeper orchestration,
+as there are many pitfalls. Instead, use a well-supported container orchestrator
+with support for Solr and Zookeeper. For Kubernetes, we provide the
+https://solr.apache.org/operator/[Solr Operator] sub project.
+There are also 3rd party Helm charts available.
 
 == How can I run ZooKeeper and Solr with Docker Compose?