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README

lite-raft is still alpha stage. the raft module is complete but some 
rewrite can occure when I come up with more elegant code.

lite-raft implement the raft consensus quorum algorithm. for more 
information on the raft algorithm see http://raftconsensus.github.io

on top of the consensus module lite-raft provide some scripts to
implement failover cluster for generic "packages". A package consist
in a collection of resource (IPs, LUNs) and programs that can run
on multiple server in a active / stand-by scenario.

======================================================================

quick tutorial on raft module:

here the steps you need to do manually for now:
- configure conf/cluster_nodes with a space separated list of 
hostname (those that will form the cluster)

- configure conf/election_timeout with a number (i use from 3 to 10,
but for production I would not go under 10) that represent the seconds
before a follower turn into candidate.

- configure conf/snapshot_period with the interval between snapshots.
this values is the number of logs before snapshotting, 
it's not time related.

- verify that the user you choose to run lite-raft with is able to
execute ssh between nodes without password and without confirmation 
for ssh key fingerprint.

- copy the lite-raft directory on every node and execute it with:
./lite-raft first-boot

to stop it on a node: ./lite-raft stop
to start (from second time and on): ./lite-raft start
to insert a test entry ./lite-raft-client set key value
to make a conditional set: ./lite-raft-client if key = X set Y
to make a get: ./lite-raft-client get key
to add a node to the cluster: ./lite-raft-client add-member node2
to delete a node to the cluster: ./lite-raft-client del-member node2
(cluster configuration change are performed online!)


======================================================================

quick tutorial on pkg module:

copy the pkg directory on the nodes that will handle the failover package.
those nodes can be different from those that run lite-raft!!! 

configure pkg/lite-raft-remote with the list of lite-raft cluster servers

copy pkg/control-scripts/template to a new file (eg. testpkg1)
edit testpkg1 and set some package parameters.

configure the lite-raft state machine to contain the package configuration:
./pkg init testpk1

run the package on every node:
./pkg run testpkg1

and verify its status:
./pkg status testpk1

the stop it on the active node:
./pkg stop testpkg1

and watch it respawn on the stand-by node!

(pkg module is still in early stage of development, it's more
a proof of concept than a finished work.)

read the code and give me feedback if you like it or not :)

my mail: luigi.tarenga@gmail.com

enjoy!

required binaries (should be complete...):
chmod
cp
date
head
hostname
ls
ln
mv
mkdir
od
pkill
pgrep
pax
rm
rmdir
sed
sleep (with decimal support)
sort
ssh
perl  (on HP-UX or where sleep don't support decimal)