Yes, target nodes have node.attr.storage_type: spinning
I've been reallocating indices during the last half-year with my own script
#!/bin/bash
INDEX=$1
NODE_TYPE=$2
if [[ -z $INDEX || -z $NODE_TYPE ]] ; then
echo "Usage: $0 <index> <ssd|spinning|hot|archive>"
exit 1
fi
curl -H "Content-Type: application/json" -s -XPUT "http://``hostname``:9200/$INDEX/_settings" -d '{ "index.routing.allocation.require.storage_type" : "'"$NODE_TYPE"'", "index.routing.allocation.require.tag" : "" }'