User talk:Jch/consul: Difference between revisions

From Alpine Linux
Line 104: Line 104:
# untie from boot server
# untie from boot server
# get ENV from consul
# get ENV from consul
# configure dnsmasq
# restart dnsmasq
# configure collectd
# configure collectd
# start collectd
# start collectd

Revision as of 08:56, 20 April 2015

This material is work-in-progress ...

Do not follow instructions here until this notice is removed.
(Last edited by Jch on 20 Apr 2015.)

Consul

Introduction

This page is currently my experimental log about consul on AL.

Downloaded package: consul-0.5.0-r0.apk from http://repos.mauras.ch/alpinelinux/x86_64/

Will prepare 5 KVM: 3 consul server (in run-from-ram mode) and 2 consul agent (a SAN (NBD) and a LXC host in data mode) on an isolated network.

We will experiment to find the right spec to allocate the consul servers for 100 to 1000 agents.

We plan to orchestrate our VM fleet based on consul events, envconsul and consul-template. All with ash scripts and smart setup.

We combine our PXE servers and the consul ones to inherit from the consul resilence (consul leader) to offer high-availability (HA) (but still in ram only) to the PXE service.

Install

We will just focus on the consul installation and configuration parts.

wget http://repos.mauras.ch/alpinelinux/x86_64/consul-0.5.0-r0.apk
apk add consul-0.5.0-r0.apk --allow-untrusted --force

Configuration

Consul v0.5.0
Consul Protocol: 2 (Understands back to: 1)

By default, there are 4 files in /etc/consul

acl.json.sample      encrypt.json.sample  server.json          tls.json.sample

Configuration Server

As in our setup we want as many PXE server (in stand-by mode) than consul server, installing a consul server is done by a script doing

  1. whoami on the LAN ?
  2. find IP of boot server (is consul leader)
  3. preconfigure OS
  4. install package from stable
  5. install package from edge
  6. rsync data
  7. install experimental consul package
  8. start consul as server
  9. untie from boot server
  10. get ENV from consul
  11. configure networking
  12. start networking
  13. start sshd
  14. (restart consul?)
  15. configure dnsmasq
  16. start dnsmasq
  17. configure ntpd
  18. start ntpd
  19. register time.service.consul
  20. configure collectd
  21. start collectd
  22. configure dhcpd
  23. configure pxelinux
  24. start in.tftp
  25. configure NFS
  26. start NFS
  27. configure darkhttpd
  28. start darkhttpd
  29. register repo.service.consul
  30. register pxe.service.consul

dhcpd will be started manually for now but later by the consul leader election.

DNSmasq with consul

apk add dnsmasq
mkdir -p /etc/dnsmasq.d
echo "server=/consul/127.0.0.1#8600" > /etc/dnsmasq.d/10-consul
echo "resolv-file=/etc/resolv.dnsmasq" > /etc/dnsmasq.d/20-resolv
echo "nameserver ${DNS1}" > /etc/resolv.dnsmasq
echo "nameserver ${DNS2}" >> /etc/resolv.dnsmasq
echo <<EOF > /etc/conf.d/dnsmasq
MASQ_OPTS="--user=dnsmasq --group=dnsmasq --interface=eth0 --conf-dir=/etc/dnsmasq.d"
EOF
rc-service dnsmasq start

Configuration Agent

We need to lauch the consul service after being able to read the IP address of the PXEserver involved.
This particuliar address will be used to join the consul cluster as agent.

  1. whoami on the LAN ?
  2. find IP of boot server (is consul leader)
  3. preconfigure OS
  4. install package from stable
  5. install package from edge
  6. install experimental consul package
  7. get standard agent config
  8. start consul as agent
  9. join consul cluster
  10. untie from boot server
  11. get ENV from consul
  12. configure dnsmasq
  13. restart dnsmasq
  14. configure collectd
  15. start collectd

Bootstrap the consul cluster

Usage

Machines discovery

List machines = list members

list PXEservers = list servers

whois active.PXEservers = get leader

Services discoevry

Register service

List services

Cheks

Key/Value storage

k/v

Events

Define event

Watch event

Triggers