Managing the shard allocation
During normal Elasticsearch usage, it is not generally necessary to change the shard allocation, because the default settings work very well with all standard scenarios. Sometimes, however, due to massive relocation, nodes restarting, or some other cluster issues, it's necessary to monitor or define a custom shard allocation.
Getting ready
You will need an up-and-running Elasticsearch installation, similar to the one that we described in the Downloading and installing Elasticsearch recipe in Chapter 1, Getting Started.
In order to execute the commands, any HTTP client can be used, such as curl (https://curl.haxx.se/) or Postman (https://www.getpostman.com/). You can use the Kibana console, as it provides code completion and better character escaping for Elasticsearch.
To correctly execute the following commands, you will need an index that is populated with the ch04/populate_kibana.sh commands. These are available in the online code.
