Josef “Jeff” Sipek

IPS: The Manifest

In the past, I have mentioned that IPS is great. I think it is about time I gave you more information about it. This time, I’ll talk about the manifest and some core IPS ideals.

IPS, Image Packaging System, has some really neat ideas. Each package contains a manifest. The manifest is a file which list actions. Some very common actions are “install a file at path X,” “create a symlink from X to Y,” as well as “create user account X.” The great thing about this, is that the manifest completely describes what needs to be done to the system to install a package. Uninstalling a package simply undoes the actions — delete files, symlinks, users. (This is where the “image” in IPS comes from — you can assemble the system image from the manifests.)

For example, here is the (slightly hand edited) manifest for OpenIndiana’s rsync package:

set name=pkg.fmri value=pkg://,5.11-
set name=org.opensolaris.consolidation value=sfw
set value=global value=nonglobal
set name=description value="rsync - faster, flexible replacement for rcp"
set name=variant.arch value=i386
set name=pkg.summary value="rsync - faster, flexible replacement for rcp"
set name=pkg.description value="rsync - A utility that provides fast incremental file transfer and copy."
set name=info.classification value="org.opensolaris.category.2008:Applications/System Utilities"
dir group=sys mode=0755 owner=root path=usr
dir group=bin mode=0755 owner=root path=usr/bin
dir group=sys mode=0755 owner=root path=usr/share
dir group=bin mode=0755 owner=root path=usr/share/man
dir group=bin mode=0755 owner=root path=usr/share/man/man1
dir group=bin mode=0755 owner=root path=usr/share/man/man5
license 88142ae0b65e59112954efdf152bb2342e43f5e7
	license=SUNWrsync.copyright pkg.csize=12402 pkg.size=35791
file 02f1be6412dd2c47776a62f6e765ad04d4eb328c
	elfarch=i386 elfbits=32
	group=bin mode=0555 owner=root path=usr/bin/rsync
	pkg.csize=191690 pkg.size=395556
file 7bc01c64331c5937d2d552fd93268580d5dd7c66
	group=bin mode=0444 owner=root
	path=usr/share/man/man1/rsync.1 pkg.csize=50628
file 006fa773e1be3fecf7bbfb6c708ba25ddcb0005e
	group=bin mode=0444 owner=root
	pkg.csize=12610 pkg.size=37410
depend fmri=consolidation/sfw/sfw-incorporation type=require
depend fmri=system/library@0.5.11- type=require

The manifest is very easily readable. It is obvious that there are several sets of actions:

specifies the FMRI, description, and architecture among others
lists all the directories that need to be created/deleted during installation/removal
specifies the file with the text of the license for the package
in general, most actions are file actions — each installs a file
lastly, rsync depends on system/library and sfw-incorporation

The above example is missing symlinks, hardlinks, user accounts, services, and device driver related actions.

Many package management systems have the ability to execute arbitrary scripts after installation or prior to removal. IPS does not allow this since it would violate the idea that the manifest completely describes the package. This means (in theory), that one can tell IPS to install the base packages into a directory somewhere, and at the end one has a working system.

It all sounds good, doesn’t it? As always, the devil is in the details.

First of all, sometimes there’s just no clean way to perform all package setup at install time. One just needs a script to run to take care of the post-install configuration. Since IPS doesn’t support this, package developers often create a transient Wikipedia article: SMF manifest and let SMF run the script after the installation completes. This is just ugly, but not the end of the world.


I’m going to try something new. Instead of posting a random thought every so often, I’m going to take requests. What do you want me to talk about next?

OpenIndiana The What and Why

You have seen me publish two posts about OpenIndiana, but neither of them really says what it is and why you should use it.

The What

OpenIndiana started off as a fork of OpenSolaris. At first, its aim was to provide an alternative to Oracle’s soon-to-be-released Solaris 11, but lately its aim shifted to “an enterprise-quality OS alternative to Linux.”

OpenIndiana is much like a distro in the Linux world. It relies on the Illumos project for the kernel and basic userspace utilities (the shell, etc.). In September 2010, Illumos forked the OpenSolaris kernel and utilities, and OpenIndiana forked the surrounding userspace (the build system for all the packages that make the system usable).

The Why

It is the technology that is the reason I started using OI. Here are some of the features that either drew me in to try OI, or made me stay.

Crossbow was the name of the project that consisted of a major revamp of the network stack. With this revamp (which was available in OpenSolaris), you can create virtual network interfaces, vlans, bridges, switches (called etherstubs), as well as aggregate links with simple commands — quickly, and all the configuration is persistent. You can dedicate both physical and virtual links to zones (see below) to create entire network topologies within one computer. (see dladm(1M) and ipdam(1M))
These days, everyone is happily setting up virtual machines whenever they need an environment they can tweak without affecting stability of other services. Solaris zones are a great virtualization technology. They allow you to set up multiple Solaris instances (called zones) that have a separate root filesystem (much like chroot). Unlike chrooted environments, having root access in a zone does not give you unrestricted access to the kernel. Zones combined with crossbow is a great combination to consolidate separate systems onto a single Solaris host. (I am currently writing a post about using zones and crossbow on a home server/router.)
Boot Environments (BE) & IPS
Long story short, if the package manager (IPS) detects that a potentially major change is going to occur during an update (e.g., a driver or kernel upgrade), it clones the current root filesystem (easy to do thanks to ZFS) and applies the updates there. It then adds a menu entry to grub to boot into this new environment. The current environment is unchanged. At your leisure, you just reboot into the new environment. If everything works — great. If, however, things break, you can just reboot into the previous BE, and mount the new BE’s root and fix things up. This means that the only downtime the system sees is the reboot or two.
There’s plenty of ZFS discussion elsewhere. My favorite features about it are (in no particular order): snapshots, deduplication, integrated volume management, and checksumming.

So there you have it. Sure, many of Solaris’s features are available in some shape or form on Linux, but they tend to be either horribly crippled, or if you are “lucky,” lacking sane management interface.

If you want to see what all this fuss is about, I suggest you grab the Live DVD (or Live USB) image on the download page and give it a try.

Powered by blahgd