I’ve been playing a bit with fabric to make some of my system administration and deployment tasks easier. As the number of servers I manage increases I need to get smarter at managing them. Fabric fills that gap nicely.

Here’s a short script I’ve been using to find what packages are missing on individual servers in a group. This script will run an rpm query on a group of hosts, before comparing which packages are installed and those that are missing.


from fabric.api import run, warn_only, env, hide, execute, task, runs_once


env.hosts = HOST_GROUP

def compare_packages(query):
        host_packages = []
        output = run('rpm -qa | grep -i ' + query)
        for line in output.splitlines():
        return host_packages

def rpm_query(query):
        output = execute(compare_packages, query)
        unique_list = set()
        for host in output.keys():
                for item in output[host]:
        print "On {:<2} servers there are {:<2} unique packages matching your query".format(len(env.hosts), len(unique_list))
        for host in output.keys():
                host_package_count = len(output[host])
                # what packages is this host missing?
                if len(unique_list.difference(set(output[host]))) > 0:
                        msg = ", ".join(unique_list.difference(set(output[host])))
                        msg = "None"
                print "{:<15} Installed packages: {:<2} Missing packages: {:<20}".format(host, host_package_count, msg)
        print "Packages: " + ", ".join(unique_list)


The env_hosts.py file should look something like this.

HOST_GROUP = ["mariadb1", "mariadb2", "mariadb3", "mariadb4", "mariadb5"]

This script is then called from the command line

fab rpm_query:query=mariadb -p 'XXXXXXXXXXXX' --hide everything

This command-line will essentially run…

rpm -qa mariadb

on each host and then compare the output. Below is an example of this output…

On 5 servers there are 7 unique packages matching your query
mariadb1 Installed packages: 7 Missing packages: None
mariadb2 Installed packages: 7 Missing packages: None
mariadb3 Installed packages: 7 Missing packages: None
mariadb4 Installed packages: 6 Missing packages: MariaDB-cassandra-engine-10.0.26-1.el6.x86_64
mariadb5 Installed packages: 7 Missing packages: None
Packages: MariaDB-compat-10.0.26-1.el6.x86_64, MariaDB-client-10.0.26-1.el6.x86_64, MariaDB-cassandra-engine-10.0.26-1.el6.x86_64, MariaDB-server-10.0.26-1.el6.x86_64, MariaDB-connect-engine-10.0.26-1.el6.x86_64, MariaDB-shared-10.0.26-1.el6.x86_64, MariaDB-common-10.0.26-1.el6.x86_64

Disconnecting from mariadb1... done.
Disconnecting from mariadb2... done.
Disconnecting from mariadb3... done.
Disconnecting from mariadb4... done.
Disconnecting from mariadb5... done.

Here we can see the unique list of packages that match the query. We can also see mariadb4 is missing the package MariaDB-cassandra-engine-10.0.26-1.el6.x86_64.