1. Make a backup of the cluster
  2. stop non-essential indexing (if possible)
  3. disable shard allocation
  4. stop and update one node
  5. start the node
  6. re-enable shard allocation and wait
  7. GOTO step 2 (until all nodes are updated)

Step 0 Make a backup

Is described here

Step 1 Disable indexing

Best would be stopping the application which uses this cluster.

Step 2 Disable shard allocation

PUT _cluster/settings
    {
    "transient": {
        "cluster.routing.allocation.enable" : "none"
    }
}

    POST _flush/synced

Step 3 Stop node

Stop the node. Reconfigure or update the node.

Step 4 Start node

Start the node and wait for it to join the cluster again.

GET _cat/nodes

Step 5

Reenable shard allocation.

PUT _cluster/settings
{
    "transient": {
        "cluster.routing.allocation.enable" : "all"
    }
}

Wait until the cluster is green again:

GET _cat/health

Step 6

Repeat Step 2-5 for each node.

Updated: