I am new to Splunk. Our organization is using Splunk Cloud and I have been asked to configure 200+ EC2 instances to forward log. I am configuring Universal forwarder on client systems to directly forward log to Splunk Cloud. I am not planning to have deployment server.
I would like to know, will I face any issue in future without deployment server? What are the things which cannot be done without DS? In future, if I plan to use DS, what possible changes do I have to make?
I don't think there really is something you cannot do without a DS, apart of course from taking benefit from the centralized management of configuration that it offers. So without a DS, each time you want to change some config on the UF (e.g. inputs / outputs) you need to touch each UF, or use some other automation tooling to do that for you.
If you later want to introduce a DS, key action to do is make the UFs a deployment client of that DS.
Depending on how you deployed the manual UF configs, you can or cannot take control over that from the DS. For example: DS cannot take control over config defined in system/local on the UF. So if you want to keep options open for the future, avoid making any changes in system/local on the UF, but bundle configuration files into apps, that you put in etc/apps on the UF. That way, you can later on have the DS take over control of those apps and manage them centrally.
Good simple example of using a deployment server here: https://docs.splunk.com/Documentation/MSApp/1.4.3/MSInfra/Createthesendtoindexerapp
This will give you better idea of why/when you would want to use a DS