I'm thinking about combining the three roles of Cluster Master, License Master and Deployment Server on the same Splunk enterprise instance. The cluster contains three indexers and all search heads are standalone.
Currently, we have around 400 forwarders using the DS and we're running Splunk 6.5.9. (Going to upgrade early next year). The current DS needs to retire and I would prefer to minimise the footprint of the entire environment.
Will this setup work well or will I see performance issues?
Shouldn't be a problem as long as your bandwidth is good enough. You may need to add a few additional cores but as there are currently no hardware requirements for a DS, I wouldn't bother with it too much.
It should not be a problem if your environment is small and if you will increase phone home interval on forwarders from default 60 seconds to higher (For example: 10 or 15 minutes) but if you look at splunk documentation http://docs.splunk.com/Documentation/Splunk/7.2.1/Indexer/Systemrequirements#Additional_roles_for_th... , splunk is saying that do not run deployment server with cluster master.
Do not colocate a deployment server on the master under any circumstances. A master node and a deployment server both consume significant system resources while performing their tasks. The master node needs reliable and continuous access to resources to perform the ongoing management of the cluster, and the deployment server can easily overwhelm those resources while deploying updates to its deployment clients.