[WIP] Etcd integration for configuration

[titilambert]

Hello !
I just started an example of what could be the etcd integration with telegraf

Here an example:
1 . Make a myconf.conf file, which will be stored in etcd, with the following content :

[tags]
  dc = "us-east-1"

[agent]
  interval = "10s"
  round_interval = true
  flush_interval = "10s"
  flush_jitter = "0s"
  debug = false
  hostname = ""


[[outputs.influxdb]]
  urls = ["http://localhost:8086"]
  database = "telegraf"
  precision = "s"


[[inputs.cpu]]
  percpu = true
  totalcpu = true
  drop = ["cpu_time*"]

2 . Send this file to etcd using the label mylabel

./telegraf  -etcd http://127.0.0.1:2379 -etcdwritelabel mylabel -etcdwriteconfig myconf.conf

3 . You can check if data is really written in etcd with

./etcdctl get /telegraf/labels/mylabel

3 . Now any telegraf agent can load this config use the label mylabel

./telegraf  -etcd http://127.0.0.1:2379 -etcdreadlabels mylabel
Config read with label mylabel
2015/12/27 20:58:34 Database creation failed: Get http://localhost:8086/query?db=&q=CREATE+DATABASE+IF+NOT+EXISTS+telegraf: dial tcp 127.0.0.1:8086: getsockopt: connection refused
2015/12/27 20:58:34 Starting Telegraf (version v0.2.4-16-ga0bb7db)
2015/12/27 20:58:34 Loaded outputs: influxdb
2015/12/27 20:58:34 Loaded plugins: cpu
2015/12/27 20:58:34 Tags enabled: dc=us-east-1 host=osselait
2015/12/27 20:58:34 Agent Config: Interval:{10s}, Debug:false, Hostname:"osselait", Flush Interval:{10s}

Notes:

• DO NOT forget to change your etcd server URL
• All data is, for now, stored in etcd in /telegraf/labels/... "folder"
• Tested with etcd 2.2.2

[sparrc]

Thank you @titilambert! I know that some people are going to be excited about using this.

I need to finish work on 0.3.0 before I can get these merged though, so don't expect progress on this for a couple weeks, and it will need to be rebased off of those changes.

[titilambert]

@sparrc Perfect! It's just a POC. If some people want to test and give feedback it could be really cool :)
Just, let me know when I can continue my work on this point.

[sparrc]

@titilambert can you rebase with master?

[titilambert]

@sparrc rebased with master !

[titilambert]

@sparrc I think we need to write some specs about this feature. Are you available on IRC ?

[titilambert]

Added:

• etcd config watcher, that reload telegraf when a change is detected in etcd.
• Labels can be configured in config file, so labels could be in etcd

WIP:

• Tests

Missing:

• Add an option to select the root folder name in etcd (default "/telegraf")
• Handle multiple etcd servers
• Handle update/set/delete in etcd
• Documentation

[sparrc]

@titilambert I'll be available tomorrow, I'll email you

[titilambert]

@sparrc I will rebase this one once #542 is merged

[titilambert]

@sparrc rebased :)