hydra/doc/manual/installation.xml
2013-01-22 14:41:02 +01:00

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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-installation">
<title>Installation</title>
<para>
This chapter explains how to install Hydra on your own build farm server.
</para>
<section>
<title>Prerequisites</title>
<para>
To install and use Hydra you need to have installed the following dependencies:
<itemizedlist>
<listitem><para>Nix</para></listitem>
<listitem><para>either PostgreSQL or SQLite</para></listitem>
<listitem><para>many Perl packages, notably Catalyst, EmailSender,
and NixPerl (see the <link
xlink:href="https://svn.nixos.org/repos/nix/nixpkgs/trunk/pkgs/development/tools/misc/hydra/default.nix">Hydra
expression in Nixpkgs</link> for the complete
list)</para></listitem>
</itemizedlist>
At the moment, Hydra runs only on GNU/Linux
(<emphasis>i686-linux</emphasis> and
<emphasis>x86_64_linux</emphasis>).
</para>
<para>
For small projects, Hydra can be run on any reasonably modern
machine. For individual projects you can even run Hydra on a
laptop. However, the charm of a buildfarm server is usually that
it operates without disturbing the developer's working
environment and can serve releases over the internet. In
conjunction you should typically have your source code
administered in a version management system, such as
subversion. Therefore, you will probably want to install a
server that is connected to the internet. To scale up to large
and/or many projects, you will need at least a considerable
amount of diskspace to store builds. Since Hydra can schedule
multiple simultaneous build jobs, it can be useful to have a
multi-core machine, and/or attach multiple build machines in a
network to the central Hydra server.
</para>
<para>
Of course we think it is a good idea to use the <link
xlink:href="http://nixos.org/nixos">NixOS</link> GNU/Linux
distribution for your buildfarm server. But this is not a
requirement. The Nix software deployment system can be
installed on any GNU/Linux distribution in parallel to the
regular package management system. Thus, you can use Hydra on a
Debian, Fedora, SuSE, or Ubuntu system.
</para>
</section>
<section>
<title>Getting Nix</title>
<para>
If your server runs NixOS you are all set to continue with
installation of Hydra. Otherwise you first need to install Nix.
The latest stable version can be found one <link
xlink:href="http://nixos.org/nix/download.html">the Nix web
site</link>, along with a manual, which includes installation
instructions.
</para>
</section>
<section>
<title>Installation</title>
<!--
<para>
Hydra can be installed using Nixpkgs:
<screen>
nix-env -f /path/to/nixpkgs -iA hydra</screen>
This makes the tools available in your Nix user environment,
<literal>$HOME/.nix-profile</literal> by default.
</para>
-->
<para>
The latest development snapshot of Hydra can be installed
by visiting the URL <link
xlink:href="http://hydra.nixos.org/view/hydra/unstable"><literal>http://hydra.nixos.org/view/hydra/unstable</literal></link>
and using the one-click install available at one of the build
pages. You can also install Hydra through the channel by
performing the following commands:
<screen>
nix-channel --add http://hydra.nixos.org/jobset/hydra/trunk/channel/latest
nix-channel --update
nix-env -i hydra</screen>
</para>
<para>
Command completion should reveal a number of command-line tools from Hydra:
<screen>
hydra-build hydra-init hydra-update-gc-roots
hydra-eval-jobs hydra-queue-runner
hydra-evaluator hydra-server
</screen>
</para>
</section>
<section>
<title>Creating the database</title>
<para>
Hydra stores its results in a database, which can be a
PostgreSQL or SQLite database. The latter is easier to setup,
but the former scales better.
</para>
<para>
To setup a PostgreSQL database with <emphasis>hydra</emphasis>
as database name and user name, issue the following commands on
the PostgreSQL server:
<screen>
createuser -S -D -R -P hydra
createdb -O hydra hydra</screen>
Note that <emphasis>$prefix</emphasis> is the location of Hydra
in the nix store.
</para>
<para>
Hydra uses an environment variable to know which database should
be used, and a variable which point to a location that holds
some state. To set these variables for a PostgreSQL database,
add the following to the file <filename>~/.profile</filename> of
the user running the Hydra services.
<screen>
export HYDRA_DBI="dbi:Pg:dbname=hydra;host=dbserver.example.org;user=hydra;"
export HYDRA_DATA=/var/lib/hydra</screen>
You can provide the username and password in the file
<filename>~/.pgpass</filename>, e.g.
<screen>
dbserver.example.org:*:hydra:hydra:password</screen>
Make sure that the <emphasis>HYDRA_DATA</emphasis> directory
exists and is writable for the user which will run the Hydra
services. For a SQLite database, the
<varname>HYDRA_DBI</varname> should be set to something like
<literal>dbi:SQLite:/path/to/hydra.sqlite</literal>
</para>
<para>
Having set these environment variables, you can now initialise
the database by doing:
<screen>
hydra-init</screen>
</para>
<para>
To add a user <emphasis>root</emphasis> with
<emphasis>admin</emphasis> privileges, execute:
<screen>
echo "INSERT INTO Users(userName, emailAddress, password) VALUES ('root', 'some@email.adress.com', '$(echo -n foobar | sha1sum | cut -c1-40)');" | psql hydra
echo "INSERT INTO UserRoles(userName, role) values('root', 'admin');" | psql hydra</screen>
For SQLite the same commands can be used, with <command>psql
hydra</command> replaced by <command>sqlite3
/path/to/hydra.sqlite</command>.
</para>
</section>
<section>
<title>Upgrading</title>
<para>If you're upgrading Hydra from a previous version, you
should do the following to perform any necessary database schema migrations:
<screen>
hydra-init</screen>
</para>
</section>
<section>
<title>Getting Started</title>
<para>
To start the Hydra web server, execute:
<screen>
hydra-server</screen>
When the server is started, you can browse to
<ulink>http://localhost:3000/</ulink> to start configuring
your Hydra instance.
</para>
<para>
The <command>hydra-server</command> command launches the web
server. There are two other processes that come into play:
<itemizedlist>
<listitem>
The <emphasis>evaluator</emphasis> is responsible for
peridically evaluating job sets, checking out their
dependencies off their version control systems (VCS), and
queueing new builds if the result of the evaluation changed.
It is launched by the <command>hydra-evaluator</command>
command.
</listitem>
<listitem>
The <emphasis>queue runner</emphasis> launches builds (using
Nix) as they are queued by the evaluator, scheduling them
onto the configured Nix hosts. It is launched using the
<command>hydra-queue-runner</command> command.
</listitem>
</itemizedlist>
All three processes must be running for Hydra to be fully
functional, though it's possible to temporarily stop any one of
them for maintenance purposes, for instance.
</para>
</section>
</chapter>
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