How Do You Create Config Files Automatically?

An anonymous reader writes "When deploying new server/servergroup/cluster to your IT infrastructure, deployment (simplified) consist of following steps: OS installation: to do it over network, boot server must be configured for this new server/servergroup/cluster; configuration/package management: configuration server has to be aware of the newcomer(s); monitoring and alerting: monitoring software must be reconfigured; and performance metrics: a tool for collecting data must be reconfigured. There are many excellent software solutions for those particular jobs, say configuration management (Puppet, Chef, cfengine, bcfg2), monitoring hosts and services (Nagios, Zabbix, OpenNMS, Zenoss, etc) and performance metrics (Ganglia, etc.). But each of these tools has to be configured independently or at least configuration has to be generated. What tools do you use to achieve this? For example, when you have to deploy a new server, how do you create configs for, let's say, PXE boot server, Puppet, Nagios and Ganglia, at once?"

Comments

A Database w/ Config File Generators

[Anonymous Coward]

At my institution, we run a MySQL database which we use to store information (such as their IP address, SNMP community) about network devices, linux servers, etc. We then have config file generators that query the database and generate the appropriate configs for Nagios and our other tools, and will restart them if needed. The idea is once you seed the initial information in the database, the config generators will pick them up and do their work so we won't have to remember to add the new hosts everywhere.

Generate config files

[atomic-penguin]

That is what configuration management is supposed to do, as far as I know puppet and cfengine do this already. I believe puppet compiles configuration changes and sends its hosts their configuration automatically, every 30 minutes.

Don't know what Unix or Linux vendor you're using puppet with. Whenever you do your network install, assuming you have some unattended install process, there should be some way to run post installation scripts. Create a post install script that will join your newly installed hosts to your puppet server. Run this post install script with kickstart, preseed, etc. at the end of the install process. Once newly installed hosts are joined to your central puppet server, then puppet can manage the rest of the configurations.

M4 baby, M4

[cerberusss]

Everyone seems to have forgotten about M4, an extremely handy standard Unix tool when you need a text file with some parts changed on a regular basis. I'm a developer and I used M4 in my projects.

In a build process for example you often have text files which are the input for some specialized tool. These could be text files in XML for your object-relational mapping tool. These probably won't support some kind of variable input and this is where M4 comes in handy.

Create a file with the extension ".m4" containing macro's like these (mind the quotes, M4 is kind of picky on that):

    define(`PREFIX', `jackv')

Then let M4 replace all instances of PREFIX:

    $ m4 mymacros.m4 orm-tool.xml

By default, m4 prints to the screen (standard output). Use the shell to redirect to a new file:

    $ m4 mymacros.m4 orm-tool.xml > personalized-orm-tool.xml

Sometimes, it's nice to define a macro based on an environment variable. That's possible too. The following command would suit your needs:

    [jackv@testbox1]$ m4 -DPREFIX="$USERNAME" mymacros.m4 orm-tool.xml
The shell will expand the variable $USERNAME and the -D option tells M4 that the macro PREFIX is defined as jackv.

Re:Templates

[johnlcallaway]

We did something even simplier on our Sun servers. We used a master server with directories that held the different app and web servers we had. Everything that needed a configuration file that had server specific items, like Apache, had a server-specific script to generate environment variables. A configuration script was created using the template:

. servEnv.sh
cat <<EOD >realConfigFile
## put config file here replacing any server specific items
## with $envVariable from the servEnv.sh script
EOD

We could redeploy a server in 10 minutes from an empty hard drive. Creating a new one took about 10 more minutes to create the servEnv.sh file.

This also gave us the ability to take scripts from dev to qc to production without having to change anything. Part of the servEnv.sh script set things like home directories and such. We could even have multiple environments on one machine.

Re:Here, let me google that for you

[jvillain]

I put all my config stuff into a noarch RPM and install it when I kickstart the box. When the configs need to be updated I update the rpm and roll it out as an update. That way we know what version of every thing we have and you can use the RPM tools to check if any thing has been changed.