Practical Ansible 2

Configuring the maximum failure percentage

In its default mode of operation, Ansible continues to execute a play on a batch of servers (the batch size is determined by the serial directive we discussed in the preceding section) as long as there are hosts in the inventory and a failure isn't recorded. Obviously, in a highly available or load-balanced environment (such as the one we discussed previously), this is not ideal. If there is a bug in your play, or perhaps a problem with the code being rolled out, the last thing that you want is for Ansible to faithfully roll it out to all servers in the cluster, causing a service outage because all the nodes suffered a failed upgrade. It would be far better, in this kind of environment, to fail early ...