I need to run virtual machines often in order to test things. For this I'm thinking to buy the NUC NUC6i5SYK, put 32 GB of memory and an M.2 SSD and run ESXi. But I need this to be able to carry this in my bag and when needed plug it in and connect from my laptop. Is this possible? Can I connect to the NUC from my laptop? Let's say using WiFi? Or do I need a monitor and keyboard?
It depends on which OS will be running on your NUC.
Lets assume you run Windows (7/8/10) PRO, you can then RDP over the network (LAN or Internet) from your laptop to the NUC.
No keyboard or mouse have to be attached to the NUC, from your laptop you'll be controlling the NUC as if you were sitting in front of it.
However, the very first setup of your NUC, including installation of the OS, will have to be done with a keyboard and mouse and screen attached to the NUC.
If you are running a non-PRO version of Windows, you'll need a third party software. Check out TeamViewer, it's unlimited & free for non-commercial use.
If you're using Linux as OS on the NUC, you're probably familiar with SSH and/or VNC and savvy enough to know how to set that up.
EDIT: oh wait, I see, you want to run ESX on the NUC.
Then I suggest you install the VMware Infrastructure Client (the old vSphere client) on the laptop and control your ESX host with that. If the ESX host is in Maintenance mode, you can create SSH access too but that is for troubleshooting only.
I was looking at much the same use - I had two HP DL380g5 servers in my garage consuming oodles of power and running my little VMWare lab on it.
In my research, I found out that you can probably install VMWare on the NUC - there are blogs online that show you how to do it for NUC5 devices and I figure that it would only be a matter of time before someone documented the process for a NUC6.
I will say one thing though - You'll have practically ZERO chance of the WiFi adapter working though - you'll be limited to using the on-board ethernetl the VMWare HCL simply doesn't support wireless adapters. Likewise if your considering using a USB network interface for your virtual swithc, but you may be able to get USB passthrough working to your VMs.
In the end, I decided to not much around with VMWare - all of my VMs are Linux anyway, so I'm using KVM on my NUC6i5SYK/32GB/256GBm2.