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https://github.com/lclarkmichalek/etcdhcp
A DHCP server backed by etcd
https://github.com/lclarkmichalek/etcdhcp
cloudnative dhcp etcd
Last synced: 7 days ago
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A DHCP server backed by etcd
- Host: GitHub
- URL: https://github.com/lclarkmichalek/etcdhcp
- Owner: lclarkmichalek
- License: gpl-3.0
- Created: 2017-07-17T21:28:45.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2017-07-18T19:08:37.000Z (over 7 years ago)
- Last Synced: 2024-08-03T20:10:34.731Z (4 months ago)
- Topics: cloudnative, dhcp, etcd
- Language: Go
- Homepage:
- Size: 21.5 KB
- Stars: 261
- Watchers: 11
- Forks: 22
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# etcDHCP
Ever wondered what was going on with your DHCP leases? Not comfortable looking
at `/var/lib/dhcp/dhcp.leases`? Feel like your DHCP should be a bit higher
availablilty, and a little bit more stateless? Prefer GRPC to ARP? Want to make
your DHCP server a legitimate microservice? Is dhcpd not cloud native enough for
you?
If any of that applies to you, I may have the DHCP server of your dreams, right
here. etcDHCP is the worlds first strongly consistent distributed DHCP server
(in the absence of any other google results), using CoreOS's etcd to ensure that
whatever happens, your leases will remain available. Well, at least, in 49% of
cases. Assuming all cases have an independent effect on your etcd nodes.
## Install
If you've never built a Go project before, I'm sorry.
```
$ go get -u github.com/golang/dep/cmd/dep
$ go get github.com/lclarkmichalek/etcdhcp
$ cd $GOPATH/src/github.com/lclarkmichalek/etcdhcp
$ dep ensure
$ go install
```
## Setup
### etcd
etcDHCP requires etcd, surprisingly enough. Notably, it requires at least
version 3.3.0. However, this version doesn't actually exist yet, so just run
master.
### etcDHCP
Because running `--help` is hard, I guess.
```
$ etcdhcp \
-etcd.discovery.endpoints localhost:2379 \
-v=2 \
-dhcp.router 10.6.9.1 \
-dhcp.dns 10.6.9.1 \
-dhcp.server-if wlan0_ap \
-dhcp.server-ip 10.6.9.1 \
-dhcp.subnet-mask 255.255.255.0 \
-dhcp.issue-from 10.6.9.10 \
-dhcp.issue-to 10.6.9.100 \
I0717 17:39:22.076564 25273 main.go:51] starting dhcp listener
I0717 17:39:22.076564 25273 main.go:45] starting admin server on :9842
```
There are tons of etcd options, most of which will probably be useless, as if
you're not yet running a DHCP server, there's a decent chance that SRV record
resolution won't be working. Notably missing is discovery via MAC address. Now
that'd be fun..
The DHCP options should be, um, well, let's hope you've configured a DHCP server
before. Plenty of things aren't supported, but you can certainly get a lot of
stuff working by writing to etcd directly.
## Operating concerns
Like all ~~good~~ cloud native software, etcDHCP exports Prometheus metrics on
`:9842`. There's also pprof endpoints exposed. I didn't implement a readiness or
liveness endpoint, as um, well they'd be a bit pointless. Also no graceful
shutdowns because github.com/krolaw/dhcp4 doesn't support context yet.
## etcd structure
```
$ ./etcdctl get etcdhcp::ips::leased::10.6.9.99
etcdhcp::ips::leased::10.6.9.99
5c:96:56:a4:be:eb
$ ./etcdctl get etcdhcp::ips::free::10.6.9.94
etcdhcp::ips::free::10.6.9.94
10.6.9.94
$ ./etcdctl get etcdhcp::nics::leased::08:9e:08:b5:af:01
etcdhcp::nics::leased::08:9e:08:b5:af:01
10.6.9.97
```
Want to add more IPs? Either restart the dhcp server with a different range,
or..
```
$ for i in `seq 200 220`; do ./etcdctl put etcdhcp::ips::free::10.6.9.$i 10.6.9.$i; done
```
Warning: IPs that aren't in the range of a running server will gradually be
phased out. They'll be removed when they are picked up by a client, and that
client allows the lease to expire.
Want to react to a device connecting? Watch the nic entry for the device's MAC
address:
```
$ etcdctl watch etcdhcp::nics::leased::08:9e:08:b5:af:01
```
Beware that renewals will cause updates to the nic key (updating/changing the
lease to one with a more recent expiry). make sure to watch for
creation/deletion events only.
Want to give a specific device a specific ip? Just associate the two, and any
DHCP discovery request will pick up the existing association.
```
$ etcdctl put etcdhcp::nics::leased::08:9e:08:b5:af:01 10.6.9.2
$ etcdctl put etcdhcp::ips::leased::10.6.9.2 08:9e:08:b5:af:01
$ etcdctl delete etcdhcp::ips::free::10.6.9.2
```
Warning: the leased keys have ttls set when a lease is issued, so you should set
this up in a cron or something.