I need to push out a new admin password to all of my remote Splunk instances/forwarders.
Can I use Splunk Deployment Manager to do this or do I need to use another tool?
You would need another tool. To push out new Splunk passwords, would need to, on each node, either:
./splunk edit user myuserid -password mynewpassword. Deployment Server can not easily be used to execute commands.
etc/auth/splunk.secret, and all other files that contain encrypts using
etc/auth/splunk.secretwhich usually includes just
etc/system/local/server.conf. These files much of course all match via
splunk.secret. Deployment Server can not be effectively used to distribute these files.
Puppet is perhaps a bit large for the word 'tool'. Like a software build engine, you kind of have to sink a certain amount of time into them to see big returns. http://www.puppetlabs.com/ cfengine is comparable. http://www.cfengine.org/
What is Puppet? Can someone provide a link if this is a recommended tool?
yes, puppet can work by pushing out copies of the above-named files to remote nodes, or by executing a command.
What about using something like Puppet? I imagine that should work.
No, deployment server only pushes out App configurations, nothing to do with users, passwords or Splunk version updates. You might want to file an Enhancement Request if this is something you foresee a need for though.