User talk:Jch/consul

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

We make the choice to have the servers running from ram...

The consul part will take care for herself.

For the apkovl files rsync must be used between active server and passive ones.
The best should be to be triggered by an update of the apkovl directory.

The dhcpd states are also kept in relative sync between active and passive dhcpd servers (the same ones).

Bur here, we are interested to the consul stuff...

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.

# read IP addr of PXEserver
# consul agent -join ${IP_PXEserver}

Consul leader

It checks that all other PXE servers are inactive and that herself is active as dhcpd..

Usage

Machines discovery

List machines = list members

list PXEservers = list servers

whois active.PXEservers = get leader

Services discoevry

Register service

List services

Key/Value storage

k/v