Enable etcd service auto start in CoreOS via systemd

Question

I have deployed a CoreOS standealone server with VMware image follow this guide to experience CoreOS.

After deploy success, I found that my CoreOS only enable Docker service, without etcd and fleet service running. Although I know how to use systemd to run etcd and fleet service manually. And I also know use a proper cloud-config can install CoreOS in which etcd and fleet service start automatically.

But I want to know that:

1. Is it possible to place a unit file in /etc/systemd/system to make systemd starts etcd service automatically?
2. If can, what is the content of the unit file?
3. If cannot, what is the other way?

Thanks

Answer 1

1. Yes. You must have a an etcd.service and fleet.service with an Install section. I've added WantedBy=default.target in mine.

2. They are already placed on coreos systems within /usr/lib64/systemd/system/. You can copy them to /etc/systemd/system/:

$ cp /usr/lib64/systemd/system/etcd.service /etc/systemd/system/
$ cp /usr/lib64/systemd/system/fleet.service /etc/systemd/system/
$ echo -e '[Install]\nWantedBy=default.target >> /etc/systemd/system/fleet.service
$ echo -e '[Install]\nWantedBy=default.target >> /etc/systemd/system/etcd.service
$ systemctl enable etcd.service
$ systemctl enable fleet.service

I'll also give you the general warning here that I have no idea what changes to /etc/systemd/ do in the long run, given CoreOSs upgrade system. An upgrade could wipe out /etc/systemd/ leaving you in a confused state as to what happened to your customized systemd scripts not managed by cloud-init.

Answer 2

The proper way to do this is with cloud-config. Specifically for VMware, you'll need to serve the cloud-config via config-drive as documented.

It's kind of a pain, but it'll work.