RapidFTR Deployment Guide

Production Failover Setup

This guide will cover how to setup two servers in a Redundant/Failover configuration.

Deploying the two servers

Setup two target servers by following instructions as specified in [[Server Deployment]]

Setting up failover

In the backup server, create the following script called "/usr/bin/couchdb_replicate.rb"

#!/usr/bin/env ruby
require 'rubygems'
require 'optparse'
require 'uri'
require 'net/http'
require 'json'

source_couch_url = nil
target_couch_url = nil
databases = nil
dry_run = false

parser = OptionParser.new do |opts|
  opts.banner = "Usage: #{__FILE__} [options]"
  opts.separator ""
  opts.separator "Options:"

  opts.on("-s", "--source https://user:pass@host:port/",
          "Required. CouchDB Source URL from which data should be pulled.") do |s|
    source_couch_url = s
  end

  opts.on("-t", "--target https://user:pass@host:port/",
          "Required. CouchDB Target URL where data will be pushed.") do |t|
    target_couch_url = t
  end

  opts.on("-d", "--databases x,y,z",
          Array, "Required. Comma-separated list of database names to replicate.") do |list|
    databases = list
  end

  opts.on("-n", "--dry-run", "Don't make requests, just print them") do |d|
    dry_run = true
  end

  opts.on_tail("-h", "--help", "Show this message") do
    puts opts
    exit
  end
end

parser.parse! ARGV

source_couch_uri = URI.parse source_couch_url
target_couch_uri = URI.parse target_couch_url

def post_uri(uri, post_params = {}, dry_run = false)
  if dry_run
    puts "Post: #{uri.to_s}"
    puts "Params: #{post_params.inspect}"
    return
  end

  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true if uri.scheme == "https"
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE if uri.scheme == "https"

  request = Net::HTTP::Post.new(uri.request_uri)
  request.basic_auth uri.user, uri.password if uri.user and uri.password
  request.body = JSON.unparse post_params
  request.content_type = "application/json"
  response = http.start { |req| req.request(request) }

  if response && response.code == "200"
    puts "SUCCESS: #{response.body}"
  else
    puts "FAILURE: #{response.body}"
  end
end

puts "Replicating #{databases.join(', ')}"
puts "From #{source_couch_uri.host} to #{target_couch_uri.host}"

target_couch_uri.path = "/_replicate"

databases.each do |database|
  puts "Replicating #{database}..."
  source_couch_uri.path = "/#{database}"
  post_uri target_couch_uri, {
    "source" => source_couch_uri.to_s,
    "target" => database
  }, dry_run
end

You can run the backup once as follows:

/usr/bin/couchdb_replicate.rb \
  -s "https://username:password@source-couchdb:6984" \
  -t "https://username:password@target-couchdb:6984" \
  -d rapidftr_child_production,rapidftr_form_section_production,rapidftr_user_production,rapidftr_device_production,rapidftr_sessions_production,rapidftr_password_recovery_request_production,rapidftr_contact_information_production,rapidftr_suggested_field_production,rapidftr_role_production,rapidftr_mobile_db_key_production

For example, if you're backing up prod1.rapidftr.com to prod2.rapidftr.com,
-s is the source URL - e.g. https://prod1-couchdb-username:prod1-couchdb-password@prod1.rapidftr.com:6984
-t is the target URL - e.g. https://prod2-couchdb-username:prod2-couchdb-password@prod2.rapidftr.com:6984

To run this automatically, we have configure a Cron job. Run:
```
sudo crontab -e
```

And in the resulting cron configuration, paste the following:

*/5 * * * * /usr/bin/couchdb_replicate.rb -s source-url -t target-url -d rapidftr_child_production,rapidftr_form_section_production,rapidftr_user_production,rapidftr_device_production,rapidftr_sessions_production,rapidftr_password_recovery_request_production,rapidftr_contact_information_production,rapidftr_suggested_field_production,rapidftr_role_production,rapidftr_mobile_db_key_production

This will run the replication script for the specified databases every 5 minutes
So even if one of the servers goes down, the second can be used straight away