How to script a standard Linux build? - linux

I'm going to rebuild my Linux box [yet] again. I have to create a few user groups, user accounts and install my standard packages. Until now I've just used the GUI tools. I was wondering if anyone has any recommendations on writing a script to create users, groups and install standard packages after I do a minimal install of my latest Fedora build? Sometimes I run Ubuntu so I'd like the script to be somewhat generic.

For .deb distros, use FAI. For .rpm distros, use Kickstart. For system management after installation, use cfengine.

Fedora and Ubuntu use totally different package managers, so you won't be able to easily do it in any sort of generic way.
In CentOS (which is RedHat Enterprise Edition with the serial numbers filed off, and so therefore pretty close to Fedora), we did this using Kickstart files. These files have a simple syntax that enabled you to specify users, groups and packages to install, and even to script some custom stuff.

While I haven't done this yet, I have a similar problem. I'm considering a virtualization host and multiple client OS (Ubuntu and CentOS being the top 2 candidates) - that way once I get the client configured as I want it, I can save it off for reloading as needed.
Doesn't get around the original setup issue, but does limit the "rebuild my Linux box [yet] again" problem.
You may want to consider it.

It may be overkill but you can check out Puppet.
From their website:
Puppet is a system for automating
system administration tasks.
I'm just starting looking for ways to automate system administration, so I don't have much experience with it yet.

If all you need to do is create users and groups and install packages then I would suggest that you just write two separate scripts.
It might be that you could share the users and groups part but only if all the distributions you use have the same policy for creating them (for example Ubuntu creates a group for each user while I am sure some distributions have a "users" group as well).
You could take a look at the useradd and groupadd commands which should be available everywhere. For Ubuntu there is also the friendlier adduser and addgroup and I would not be surprised if Fedora has a set of similar commands.
After groups are setup you just need to feed the package manager a big list of packages you need to have installed. Trying to install packages which are already installed should be safe, so you could install the packages you need on a "clean" new install and then dump a package list.
So to summarize: If you don't plan to support more than two distributions then I suggest just writing the two scripts separately.

Another option to help with constantly rebuilding a box is Norton Ghost, with ghost you can make an image and then just re-image the drive as needed. You install it and configure it to your liking, then take an image.

It's gonna be difficult to make the script generic, but you could use any sort of scripting tool (bash, or ruby or whatever) and try and check what distro is running and then run the appropriate commands to install software. There are various ways to check what distro is running here
Creating groups should be the same on all distros, and you may even be able to drop in an already configured /etc/passwd and /etc/groups (though I haven't tried that, and it may not work).

The response above, about the different distros using different methods is dead on. It's like trying to use the same part for a Chevy and a Ford (there's the car analogy, for you).
The easiest method I've found is to learn about setting up partitions for the different mount points i.e. / ; /home ; /var ; /opt are the big ones.
This lets you keep your users, groups, and many of your apps during your rebuilds. Changing distros will break a lot of things, but your user accounts should still be there.

Related

What is the safest way to deliver an Application to novice Linux users?

My customers are novice Linux users, and so am i.
When I gave them my App packaged with ansible, they saw ansible problems, when i gave them manual steps, they also screwed that up, now i have 3 last options, either a perl/bash script or a snappy/deb/rpm package or Linux containers, can anyone share their experience on the safest way to see less problems when installing my app (Written in C)?
This depends on the nature of your application. Debs, rpms etc. are all fine but depend on which distro you're using.
If it's C application, it might make sense to make it a static binary. That way, you'll have to download a single file and just click on it to make it run. It will be big but it should work fine regardless of what else is there. Otherwise, you'll have to worry about dependencies etc.
As it was commented before it depends what you did to deploy the product.
In general, if you have dependencies (previous packages that you assume were already installed) or your installation is complex - use rpm or deb.
However if you target multi-platform bare in mind you will have at least two releases (one rpm and one deb...)
If configuration or installation is easier you can just give them an install script.
If your application requires a specific environment with specific configuration/packages I'd consider containers although I never done that personally before.

Distributing and Updating Software Applications to Linux envaranment

Currently I'm manually distributing and updating two applications over 50 computers running CentOS 6.5 and Ubuntu 14.04. Each time the new version is available for either of my applications,i have to copy all files and update it in all the computers by manually.its very time consuming and frustrating.
to avoid this manual process over 50 computers,I like to maintain a central server that contain the latest version of the applications and whenever need to install or update just type a command in client pc like we use in CentOS and Ubuntu to install a software
in Ubuntu
sudo apt-get install vlc
and in Cent OS
sudo yum install vlc
one of the programs written in java and other is written in python
I google it and can't find any good and useful source about how to do this.
some one alrady done this or knows how to achive this please help.
You need to create packages to make this happen.
Ubuntu uses the Debian package format, so you can use Debian's New Maintainer's Guide, which is the canonical tutorial on how to create a Debian package. It makes the assumption that you're going to upload the package to Debian, which in your case isn't true, but that just means you need to skip some sections of the document.
For RPM, there isn't such a document AFAIK, but there is the book 'max rpm' (which unfortunately is somewhat outdated), and fedora has augmented that with some guidelines and best practices which they've put on their wiki. Since RHEL is created by forking fedora and stabilizing that, and since CentOS is based on RHEL, what goes for fedora goes for CentOS, too.
These methods will create packages manually, which is always the best way and will result in the least problems afterwards. However, they take time. If you don't want to spend that time, there are also a few options to generate packages which will automate part or all of the job for you. Personally, however, I'm not a fan of these methods and therefore wouldn't recommend them.
Finally, another option is to not create packages, but to use a config management system like puppet to automate the deployment. It's even available in Ubuntu and EPEL.
edit I notice you may actually be asking about creating a repository instead. That's a different thing. There are several tools to help you do that; at core, all they do is run createrepo for RPM packages, or dpkg-scanpackages for debian packages. You can do that yourself, or investigate time in a tool like reprepro or aptly or some such.

How to test for services in Linux?

I've been assigned a project to write some kind of a script that will perform a sanity check on a Linux server implementation to determine if it has a number of dependencies installed before source code is deployed to it. I need to check for the presence of applications such as PHP, Nginx, PostgreSQL, etc and likely confirm version numbers for these as well. These dependencies are required for the given source code to be able to run properly on the server.
The problem is, I'm not sure how to approach this due to my novelty in working with Linux. I've done some research on this and thought that the solution might be to use a combination of combing through the list of running services with a command such as "chkconfig --list" and pinging individual applications with commands such as "php -v" and then asserting the that results from these equate to what I'm looking for.
Pardon if that makes no sense whatsoever, I really am new to this. I was then thinking I could place these "tests" inside of a shell script or something that could be run whenever a test on the server needed to be executed. I would aggregate the true/false results of my assertions and output whether the sanity check passed based on that. Any guidance would be greatly appreciated.
Thank you.
Revision: In lieu of a shell script, I was also thinking I could write this in Python. Does anybody know of any good Python libraries that allow querying of system services?
If your target systems are managed by reasonable people, the software will be managed by the packaging system. On Redhat, Fedora, CentOS or SUSE systems that will be RPM. On any system derived from Debian it will be APT.
So your script can check for one of those two packaging systems. Although be warned that you can install RPM on a Debian system so the mere presence of RPM doesn't tell you the system type. Packages can also be named differently. For example, SUSE will name things a bit differently from Redhat.
So, use uname and/or /etc/issue to determine system type. Then you can look for a particular package version with rpm -q apache or dpkg-query -s postgresql.
If the systems are managed by lunatics, the software will be hand-built and installed in /opt or /usr/local or /home/nginx and versions will be unknown. In that case good luck.

yum/ zypper for non-root installation in independent rpm database

My company is developing a Linux based software product which is shipped to different customers.
The product it self consits out of small software components which interact with each other.
What we usually ship as an update/ new release to the customer are the the current versions of the different software components e.g. compA-2.0.1, compB-3.2.3 and compC-4.1.2
Currently we employ a rather simple shell script for the installation/ upgarding process. However, we'd like to move forwarard to state of the art packaging, mainly to have an easy way of swapping different versions of components, keeping track of files and the packages they belong to and also to provide the customers with an easier interface for the update/ installation.
The software components are installed in different directories, depending on the customers demands. So it could be in /opt, /usr/local or something completely different.
Since the vast majority of our customers runs on rpm-based Linux distributions we decided for rpm-packages instead of dpkg.
In rpm terms our problem is a non-root installation. This is realativly straight forward using the following features:
own rpm database using the --dbpath option
installing in different locations using the Prefix mechanism
optional: disabling auto library dependancies using AutoReqProv: no in the rpm spec file
Using those features/ options allows us to create rpm packages which can be installed using the rpm command line tool as non-root user.
However, what we really would like to see is to install those packages via a http repository with either yum or zypper. The latter one is the tool of choice in SUSE based distributions.
The problem we see is, that non of the tools is providing the required alternative rpm database option (--dbath in rpm) and prefix support required for a non-root installation.
Does anybody have a suggestion/ idea how to deal with this issue? Is there maybe a third package-tool with we're not aware of?
Or should we maybe go a totally different route? I had a play with GNU stow and wrote some very simplistic yum-like logic around it - but then I would basically start my own package installation tool which I tried to circumvent.

Should I use another user than the root when installing NGiNX

I herd that it would be better to use a sub-user for installing NGiNX. Is it true? I am thinking to use NGiNX to install virtual-host that my clients could use for there website and I don't want them to have to much control over NGiNX...
I am using Ubuntu Linux distro.
Thanks in advance for any help and/or tips.
How are you planning to install these applications? Since you say you're using Ubuntu, then I would assume that you'll be installing apps via either the graphical manager or by apt-get or aptitude.
If you're using the graphical program manager, then it should prompt you for your password; this performs a sudo under the hood.
If you're using either apt-get or aptitude or something similar, those programs need to be run as root to install.
In both instances above, the installation scripts for the packages will (should) handle any user-related issues that are necessary for the program you're installing to function properly. For example, when I did an apt-get install jenkins, the installation scripts automatically created a jenkins user for me, and my Jenkins CI server runs as the jenkins user automatically.
Of course, if you're compiling all of these programs by hand, all bets are off and you'll need to figure out how best to do all of this yourself. Of course, if you're compiling these programs by hand to get them installed, I'd have to question why you're using Ubuntu in the first place; one of the best parts to using a Linux distribution with sane package management capabilities is actually USING said package management! (Note: by this statement, I mean anything Debian-based for sure; and I understand that Red Hat's yum provides very similar capabilities, but I haven't used anything RedHat since around 2003.)
You don't want a process to have any more access than it needs. So yes, you should use a user besides root -- one that has the minimal privileges required to read the files it needs. Typically this involves creating a new nginx (or www or similar) user specifically for the task.

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