What gems do you recommend to use for this kind of automation? - ruby

Question

I have to create a script to manage maintenance pages server for my hosting company.
I will need to do a CLI interface that would act like this (example scenario) :
(here, let's suppose that mcli is the name of the script, 1.1.1.1 the original server address (that host the website, www.exemple.com)
Here I just create the loopback interface on the maintenance server with the original ip address and create the nginx site-specific config file in sites-enabled
$ mcli register www.exemple.com 1.1.1.1
[DEBUG] Adding IP 1.1.1.1 to new loopback interface lo:001001001001
[WARNING] No root directory specified, setting default maintenance page.
[DEBUG] Registering www.exemple.com maintenance page and reloading Nginx: OK
Then when I want to enable the maintenance page and completely shutdown the website:
$ mcli maintenance www.exemple.com
[DEBUG] Connecting to router with SSH: OK
[DEBUG] Setting new route to 1.1.1.1 to maintenance server: OK
[DEBUG] Writing configuration: Ok
Then removing the maintenance page:
$ mcli nomaintenance www.exemple.com
[DEBUG] Connecting to router with SSH: OK
[DEBUG] Removing route to 1.1.1.1: Ok
[DEBUG] Writing configuration: Ok
And I would need a function to see the actual states of the websites
$ mcli list
+------------------+-----------------+------------------+
| Site Name | Server I.P | Maintenance mode |
+------------------+-----------------+------------------+
| www.example.com | 1.1.1.1 | Enabled |
| www.example.org | 1.1.1.2 | Disabled |
+------------------+-----------------+------------------+
$ mcli show www.example.org
Site Name: www.example.org
Server I.P: 1.1.1.1
Maintenance Mode: Enabled
Root Directory : /var/www/maintenance/default/
But I never did this kind of scripting with Ruby. What gems do you recommend for this kind of things ? For command line parsing ? Column/Colorized output ? SSH connection (needed to connect to cisco routers)
Do you recommend me to use a local database (sqlite) to store meta datas (Stages changes, actual states) or do you recommend me to compute on the fly by analyzing nginx/interfaces configuration files and using syslog for monitoring changes done with this script ?
This script will be used at first time for a massive datacenter physical migration, and next for standard usages for scheduled downtimes.
Thank you

Answer 1

First of all, I'd recommend you get a copy of Build awesome command-line applications in Ruby.
That said, you might want to check
GLI command line parsing like git
OptionParser command line parsing
Personally, I'd go for the SQLite approach for storing data, but I'm biased (having a strong SQL background).

Answer 2

Thor is a good gem for handling CLI options. It allows this type of organization in your script:
class Maintenance < Thor
desc "maintenance", "put up maintenance page"
method_option :switch, :aliases => '-s', :type => 'string'
#The method name is the name of the task that would be run => mcli maintenance
def maintenance
#do stuff
end
no_tasks do
#methods that you don't want cli tasks for go here
end
end
Maintenance.start
I don't really have any good suggestions for column/colorized output though.
I definitely recommend using some kind of a database to store states though. Maybe not sqlite, I would probably opt for maybe a redis database that stores key/value pairs with the information you are looking for.

Answer 3

We have similar task. I use next architecture
Small application (C) what generate config file
Add nginx init.d script new switch update_clusters. This script will restart nginx only if config file is changed
update_clusters() {
${CONF_GEN} --outfile=/tmp/nginx_clusters.conf
RETVAL=$?
if [[ "$RETVAL" != "0" ]]; then
return 5
fi
if ! diff ${CLUSTER_CONF_FILE} /tmp/nginx_clusters.conf > /dev/null; then
echo "Cluster configuration changed. Reload service"
mv -f /tmp/nginx_clusters.conf ${CLUSTER_CONF_FILE}
reload
fi
}
Set of bash scripts to add records to database.
Web console to add/modify/delete records in database (extjs+nginx module)