Avoiding/reducing multiple installations for Travis-CI builds - linux

For our Travis-CI builds of the Jailhouse hypervisor, we have a rather costly environment setup which consists of a partial distribution update to pull in a recent make version (>=3.82, the default one is still only 3.81 - Ubuntu...), a cross toolchain for ARM and a 100 MB package of prebuilt Linux kernel sources that we need to compile an out-of-tree module.
To reduce the build time and the number of kernel downloads, we currently build all configuration variants sequentially in a single run (make; make clean; make...). That was fine for checking for build breakages, but with the addition of a Coverity scan, which depends on the build outputs, it no longer works. Switching to a build matrix seems the obvious solution, at the price of multiple installations because Travis-CI seems to be unable to reuse them during such builds. While we currently only have 3 configuration variants, this will increase in the future (e.g. every ARM board added will increase it by one), thus the approach does not really scale.
Do we have any alternatives? I already looked at caching, available via the docker-based build, but lacking sudo support there prevents this approach. Other ideas?

You should change your build to do this
cov-build --idir <target1> make; make clean
...
Use different intermediate directories for each build. Then go back later and run
cov-analyze --idir <target1>
cov-commit-defects --idir <target1> --stream <target1>

Related

Compiling the linux kernel source and not sure if this correct behaviour?

I'm compiling the linux source code on a different machine to where I will be testing this (I'm trying to see if I can trace if/where a commit that is causing some weird behaviour on my machine), and I therefore want to try to build packages which I can install on the test machine.
The test machine runs Fedora, so, therefore, I would use make binpkg-rpm to generate those packages.
The output I get is two rpms -- one for the kernel and one for the headers. All good.
Some things I noticed at this point, however:
The kernel rpm is HUGE -- like 1G+ in size.
The kernel-headers package obsoletes kernel-headers (and the rpm generation actually warns of this). Removing this package after installation makes Fedora want to remove a TON of other packages.
There are no separate module packages (e.g. kernel-modules, kernel-modules-extra)
So a few questions I have regarding the compilation process (and I cannot find any documentation on the web to answer these)
Why is the generated kernel rpm so big?
Why are there no separate modules rpms? Is there a switch I need to use to generate these?
Why does the kernel-headers generation throw that obsoletes message and why does removing it make Fedora want to remove so many other packages?
I did use the kernel config of the current running kernel (i.e. I copied the config from the /boot folder and renamed it .config)
Many thanks in advance for any guidance, even if it's just pointing me to a page which answers my questions (that my hours of searching didn't uncover)

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.

Using puppet to build from source

How can I use puppet to build from source without using multiple Exec commands?. Do we have modules for it on forge that I could use?
It's possible to use Puppet to build applications from source without using execs, possibly with a custom written type and provider. Otherwise, yes, it'd have to be a few different exec resources with onlyif, creates etc. statements to stop them running every time the agent ran.
Puppet's model of configuration management is known as a desired state model: you define the end state of the system and let the system. This is why exec's are generally avoided in Puppet: they don't fit a desired state model. It also makes things like updating the application, or dealing with unknowns like a partial failure of the compilation that creates a required file.
In my opinion, I would not recommend using configuration management to build applications from source at all. There are a few issue inherent with doing so (this is not just for Puppet, but most config management languages):
Slower runs, as running the compilation can be longer and detecting that it's complete is normally a slightly trickier tasks
Issues with half complete state or failure: if the compilation breaks halfway through it's both harder to detect and resolve
Making the compilation idempotent: You have to wrap the command in logic that detects if the installation has already been done. However, this is difficult, as things like the detection of a flag file or particular binary could occur even when the compilation ends in failure
Upgrading or changing: There's no easy way to upgrade or change the application. A package would be easier to do this with.
This sounds like something that would be better served by packaging, using tools such as FPM or just native package building tools such as rpmbuild.

How to be able to "move" all necessary libraries that a script requires when moving to a new machine

We work on scientific computing and regularly submit calculations to different computing clusters. For that we connect using linux shell and submitting jobs through SGE, Slurm, etc (it depends on the cluster). Our codes are composed of python and bash scripts and several binaries. Some of them depend on external libraries such as matplotlib. When we start to use a new cluster, it is a nightmare since we need to tell the admins all the libraries we need, and sometimes they can not install all of them, or they only have old versions that can not be upgraded. So we wonder what could we do here. I was wondering if we could somehow "pack" all libraries we need along with our codes. Do you think it is possible? Otherwise, how could we move to new clusters without the need for admins to install anything?
The key is to compile all the code you need by yourself, using the compiler/library/MPI toolchains installed by the admins of the clusters, so that
your software is compiled properly for the cluster hardware, and
you do not depend on the admin to install the software.
The following are very useful in this case:
Ansible, to upload/manage configuration files, rc files, set permissions, compile your binaries, etc. and deploy a new environment easily on new clusters
Easybuild to install your version of Python with all the needed dependencies, and install other scientific software thanks to the community supported build procedures
CDE to build a package with all dependencies for your binaries on your laptop and use it as-is on the clusters.
More specifically for Python, you can use
virtual envs to setup a consistent set of Python modules across all clusters, independently from the modules already installed; or
Anaconda or Canopy to use a Python scientific distribution
to have a consistent Python install across all clusters.
Don't get me wrong, but I think what you have to do so: stop behaving like amateurs.
Meaning: the integrity of your "system configuration" is one of the core assets of your "business". And you just told us that you are basically unable of easily re-producing your system configuration.
So, the real answer here can't be a recommendation to use this or that technology. The real answer is: you, and the other teams involved in running your operations need to come together and define a serious strategy how to fix this.
Maybe you then decide that the way to go is that your development team provides Docker buildfiles, so that your operations team can easily create images on new machines. Or you decide that you need to use something like ansible to enable centralized control over your complete environment.
That's what venv is for, it allows you to create a portable customized environment easily, with exactly what you need and nothing more.
I completely agree with https://stackoverflow.com/users/1531124/ghostcat
but here is the really bad answer that will cause you a lot of problems in near future!!!:
if you need some dynamic library and you are not planning to upgrade them in future, you can try copying all needed libs to a folder in your app and use an script to launch the app:
#!/bin/sh
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path/to/your/lib/folder
./myAPP
but keep in mind that this is bad practice.
Create a chroot image, like here - click. Install everything you need and then you can just chroot into it on any machine.
I work on scientific clusters as well, and you are going to find that wherever you go.
I would only rely on the admins on installing the most basic stuff. That is:
- Software necessary to build your software or run the most basic stuff: compilers and most basic utilities (python, perl, binutils, autotools, cmake, etc.).
Software libraries that make use of I/O devices: MPI, file I/O libraries...
A queue system (they already have it most of the time).
Environment modules. This is not a must, but it really helps you get the job done, specially if you mess with different library versions or implementations (that's my case, for example).
From that point on, you can build and install on your own directories all the software you use most of the time.
This does not mean that you cannot ask an admin to install some libraries. If you feel that many people is going to benefit from that, then you should request its installation. In addition, you may need some specific version or some special features which are not used most of the time, but you really need them. A very good example is with BLAS libraries (basic lineal algebra subroutines):
You have lots of BLAS implementations available: the original BLAS, Intel MKL, OpenBLAS, ATLAS, cuBLAS
If that is not enough, the open source versions usually offer multiple configuration options: serial version, parallel version with PThreads, parallel version with OpenMP, parallel version with MPI...
In my particular case, most of the software that I felt was necessary for many users in the cluster ended up being installed by the admins without any problem (either me or other users requested it), but you also have to keep in mind that in a cluster there can be many users and a single person/team is not able to attend the specific requirements you need, specially if you are able to do so.
I think you want to containerize your application in some way. Two main options (because docker/rkt and similar things are way too heavyweight for your task if I understand it correctly) in my opinion are runc and snappy.
Runc relies on OCI runtime specification, you need to create an environment (that is very similar to chroot environment in that you need to copy everything you software uses in one directory) and then you'll be able to run your application with runc tool. Runc itself is just one binary, at the moment it requires root privileges to run (hello, cluster admins), but there are patches at least partly solving that, so if you build your own runc and there are no blocking things wrt root privilege requirements you may be able to run your application with no administration overhead at all.
Snappy is similar in that you need to prepare a snap package for your application, this time using snapcraft as an assistant tool. Snappy is probably a bit easier in creating an application image and IMO is certainly better for long-term support because it clearly separates your application from the data (kinda W^X, application image is a read-only squashfs file and application can only write to a limited set of directories). But at the moment it will require your cluster admins to install snapd and to perform some operations like snap installation that require root privileges. Still, it should be better than your current situation, because that's just one non-intrusive package to install.
If these tools don't fit for some reason, there is always an option to make something of your own. That won't be easy and there are many subtle details that can bite you when doing that, but it can be done, compile all of your dependencies and applications into some path, create wrapper scripts to set up PATH and LD_LIBRARY_PATH environment for your components and then bring that directory into the new cluster, run wrapper scripts instead of target binaries and that's it. It's similar to what XAMPP does, they have quite a number of integrated things packaged into one directory that works across many distributions.
update
Let's also add AppImage into the mix, theoretically it can be a savior for your case, as it specifically does not require root privileges. It's kinda inbetween Snappy and rolling your own, as you need to prepare your application directory yourself (snappy can manage some of dependencies with snapcraft when you just specify "I need this Ubuntu package"), add appropriate metadata and then it can be packaged into single executable.

LINUX: Upgrading a production machine

Our production machines are running on debian etch. Now, they finally released lenny, the day will come we need to upgrade these systems. How can I do this with minimal risk? Are there any premises, preparations of fall-back scenarios and do I need a plan B in case something goes wrong? Besides the binary packages handled by the debian installer there are a couple of compiled applications running on the machines.
Personally I wouldn't upgrade any OS on an important server. OS upgrades always have the potential for subtle bugs, whether it's Windows, Linux or anything else. Debian has got better than it used to be in this regard; dist-upgrade doesn't hose the machine nearly as often as it used to back in the day. But for production machines there is no point in risking it.
Set up new servers with a fresh OS and application deployment and swap them in as needs arise. There is no need to hurry to replace Etch companywide in one go. It will be supported with security updates for a while yet.
Having just gone through that transition for some dev boxes, I wanted to point out that you'll probably want to recompile any custom libraries that you'll be linking against. Lenny uses GCC 4.3, whereas Etch uses 4.1. The output from either compiler isn't very compatible with the other. You may need to install the gcc-4.1 package to do things like compile custom kernel modules.
If you're using 3rd party tools that have a plugin interface, you may have challenges there. I've been having troubles getting Matlab plugins (mex files) to work.
I'd suggest starting with a test system. After hammering it for a while and verifying that everything's working, switch it to be a production box.
Most people don't update production servers for exactly this reason - if it's working correctly, you wouldn't update unless you had a compelling reason.
Assuming you have a dev box built similarly to the production machine, you can simulate the update on the dev box.

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