Installing Plone and other Products

Where to keep Products

ZEO clients that use the same server for storage need to have the
exact same products installed. It's easier to just maintain one
directory of products and make sure that all clients can see it.
Accordingly, I create a '$BASE/products' directory and create the
'Products' directory within each client as a symlink to the
directory[1]::

$BASE/
products/
CMFCore/
CMFPlone/
# etc.
client0/
Products@ -> ../products
# etc.
client1/
Products@ -> ../products
# etc.
# etc.

This directory is where the contents of the Plone-x.y.z tarball
and all other add-on products should be placed. To create this structure,
download the "Plone Core source
tarball":http://sourceforge.net/project/showfiles.php?group_id=47214&package_id=112603 and place it in /tmp. Then
execute the following commands::

cd /tmp
tar zxf Plone-x.y.z.tar.gz
cd $BASE
mkdir products
mv /tmp/Plone-x.y.z/* products
rm -r /tmp/Plone-x.y.z*
cd client0
rm -r Products
ln -s ../products Products
# repeat the last three steps for all Zeo clients/Zope instances

How to organize and maintain Products

I use subversion to keep this directory of products under version control
for the following reasons:

* You can start with a base set of products that are common to
several customers or sites and create branches where customer or
site-specific products are added or included as shown below.

* You can use subversion's "externals
feature":http://svnbook.red-bean.com/en/1.1/ch07s03.html to
include other products that are maintained in separate subversion
trees. This will be even more useful as the Collective is moved to
subversion. [2]

* You can tag the directory each time you deploy the products to the
production server so that you have a repeatable deployment. This
makes trouble-shooting a production installation locally as easy
as making a new Zope instance, checking out the products directory
with the appropriate tag, and copying over the production Data.fs.
It also simplifies cluster installations.

* If you need to make changes to products that you did not write but
are unable or unwilling to contribute them back to the authors, you
can keep them under version control and use 'svn merge' to merge
them into newer versions as they are released [3]

I generally check out the products directory into '$BASE' as a working
copy on my development machines, but use "'svn
export'":http://svnbook.red-bean.com/en/1.1/re10.html to get just the
files without the svn metadata on the production and staging machines.
This also helps to enforce the rule that no changes should be made in
production/staging without being tested in a development environment,
as you are unable to check in new files or changes to existing files
from an exported copy. (Of course it doesn't stop someone from
changing a file and not recording that fact in version control, but
the thought of doing that just makes me sick, so let's move on.) On
your development machines you will want to
"configure":http://svnbook.red-bean.com/en/1.1/ch07.html#svn-ch-7-sect-1.3.2
subversion to ignore .pyc files.

Permissions and ownership

It is important that the products directory and files and
directories contained within it have the proper permissions and
ownership. The user that Zope runs under needs to be able to write to the
directories in order to create the byte-code (*.pyc) files when the
products are first installed. However, the source files should not
be writable by the Zope user. The solution is to have the products
directory and everything under it owned by another user, to change
the group ownership of the directories to the zope group, and to
turn on the group write bit::

# The first command is not necessary if you have checked out
# or otherwise populated the products directory yourself
sudo chown -R $youruser:$yourgroup products
find products -type f|xargs chmod g+r
find products -type d|xargs chgrp zope
find products -type d|xargs chmod g+rxw

You will have to run the last two 'chgrp' and 'chmod' commands
as root or via sudo if you are not a member of the Zope user's
group.

Test your installation

Once your products are in place and the permissions are set, test
your installation by starting up (or restarting) Zope and adding a
new Plone site from the ZMI. Check to make sure that the *.pyc files
are written in the product directories. If everything looks good you
can move on to configuring Apache as a front-end.

.. [1] You can also specify the Products directory explicitly in the zope.conf file for each client/instance.

.. [2] Make sure to use an URL for the external Product that represents a tag rather than a branch or the trunk, otherwise you may get updates that you haven't tested

.. [3] See the discussion of "vendor branches":http://svnbook.red-bean.com/en/1.1/ch07s04.html in the svn book for more information