Electrum has a thin client. Does not need a full block chain.
It is available as an RPM for Fedora which will run on Centos 7 => See https://www.rpmfind.net/linux/rpm2html/search.php?query=electrum and the Rawhide version is the latest which will run on Centos 7 - you will need to source out and install dependencies one at a time as it complains they are missing and retry until it intalls.
See also http://docs.electrum.org/en/latest/merchant.html It will run command line as a daemon or you can set up Remote X access with Qt but as stated by ThomasV it can be used completely command line who would know best of all.
You will need to open the ports needed 7777 and 9999 in the firewall and once you launch it issue a => netstat -anp | grep 7777 to make sure it is listening
Then do => electrum daemon load_wallet
Do => electrum -h - to see all the commands available from the command line of via a curl call. See the link at the bottom for more on curl calls with software like PHP or website webstores
However if you leave it running as launched from the shell it is likely to die so . . . then set it up to start on boot and respawn if it fails
And the service file, in /etc/systemd/system/electrum.service:
Description=Electrum Bitcoin thin client
ExecStart=/usr/bin/electrum daemon start
Assuming above you change the "User" to <= whoever you will run it as and assuming you installed the rpm - the path to electrum is then correct as the path. Enabling that with => systemctl enable electrum <= (on Centos 7) will make sure Electrum always starts on boot. You will need to load the wallet manually if it fails and restarts or you reboot however.
see also Checking/polling a balance of an address in Electrum via the command line/RPC