Installing and removing packages with Quattor

05 April 2013

We describe here the basic Pan statements and data structures for installing, removing and upgrading software packages. Other documents describe the implementation and the client-side details. We focus now on the user-visible interface: the Pan code.

Package management

Installing a package

In their simplest version, we may install a package by just creating an empty entry under /software/packages:

"/software/packages/{perl-JSON}" ?= nlist();

With this, we tell the package manager that we want perl-JSON installed. Note that the curly braces are mandatory as package names can contain characters that must be escaped in the PAN syntax. We don’t care about the version or architecture (yum will determine that for us) and the use of conditional assignment (?=) ensures that any existing, more specific setting is not over-written. Also, if we trust Yum for choosing the correct dependencies, we don’t need to specify anything more.

To specify particular versions and/or architectures, the simplest way to declare that is to use a function. Imagine we wanted to install perl-JSON version 1.2.3, only in its x86_64 architecture. The pkg_repl function is the preferred way to declare that:

"/software/packages" = pkg_repl("perl-JSON", "1.2.3", "x86_64");

Note that the package name must be passed to pkg_repl unescaped. Again, Yum will take care of the dependencies, and will lock only the version of perl-JSON.

If you prefer you can specify all packages using functions, see the section Helper functions for package management.

Keeping a family of packages at the same version

The pkg_repl form accepts wildcards, and may be used for ensuring some packages move together. For instance, a package and its libraries, the kernel and many modules…

"/software/packages" = pkg_repl("openldap*", "2.6.24", "x86_64");

This will ensure that any packages matching openldap will be kept to version 2.6.24, if such a version exists. Now we can keep openldap, openldap-client, openldap-servers and openldap-devel in line!

The above statement will only install openldap and its dependencies. If we want to install openldap-devel we still have to declare it:

"/software/packages/{openldap-devel}" ?= nlist();

Now we are sure that we’ll get the correct version.

Deleting a package

Just remove its entry from the profile:

"/software/packages/{perl-JSON}" = null;

this will make the backend remove perl-JSON only if no other package in the profile depends on it.

Repository management

The /software/repositories is a list of repositories. Each entry may declare:

  • name: repository name
  • owner: a contact person or e-mail address
  • priority: an integer between 1 and 99. Defaults to 99. The lower the number the more priority the repository has.
  • enabled: a boolean indicating whether the repository should be enabled or not. Defaults to true.
  • gpgcheck: whether to check the GPG signature of the packages that come from this repository. Defaults to false.
  • includepkgs: list of packages authorised from this repository. If present, only packages in this list may be taken from this repository. Wildcards are allowed in this field.
  • excludepkgs: list of packages from this repository that are banned. If present, no package from this list will be taken from this repository. Wildcards are allowed in this field.
  • skip_if_unavailable: whether Yum (and thus SPMA) should fail if it cannot access this repository. Defaults to false. Use with caution, or network glitches may remove software you truly want!
  • protocols: list of ways to access this repository. In the new SPMA it should contain only one entry, with the following data structure:
    • name: protocol name. Unused currently.
    • url: URL where the repository is located. Maps to Yum’s baseurl.
    • cacert: If the repository is to be accessed over HTTPS, path to the CA certificates.
    • clientkey: if the repository is to be accessed over HTTPS, path to the client’s private key.
    • clientcert: if the repository is to be accessed over HTTPS, path to the client’s certificate.
    • verify: if the repository is to be accessed over HTTPS, whether or not verify the server’s certificate..

Yum can do even more than this. We’ll add support for more features as their need arises.

Helper functions for package management

There are several functions to help with complex package manipulations. The components/spma/functions template contains their full descriptions. We list here the simplest (and most frequent) uses.

They all take the following form:

"/software/packages" = pkg_<op>("package-name", "package-version",
    "architecture", list("flags"));

where only the package name is mandatory. Each function also takes care of escaping the package name for you.


Deletes a package from the profile. In most cases this is equivalent to

"/software/packages/{a-package}" = null;

This function allows to remove only one version or architecture of such a package, while preserving all others.

Given the way we can now simplify our Pan code, the use of this function is probably a code smell.


Adds a package to the profile, raising an error if it was already defined. You usually prefer pkg_repl, which is idempotent.


Adds a package to the profile. Typically, it replaces any other versions of this package.

If given the multi flag, versions already defined in the profile are preserved. This is useful if you need to declare multiple kernel versions, for instance.


If the package given as an argument exists in the profile, replaces its version and/or architecture. It doesn’t add or remove any packages.