Question

I have a program that I build from source. For this I’m using the script resource. What is a good way to implement the logic for installation and update? Right now I just have installation implemented with the built-in not_if conditional.

script "install_program" do
  not_if {File.exists?('/program')}
  interpreter "bash"
  user "root"
  cwd "/tmp"
  code <<-EOH
    wget http://www.example.com/program.tar.gz
    tar -zxf program.tar.gz
    cd tarball
    ./configure
    make
    make install
  EOH
end

Answer 1

First and foremost, if you have the means to host an internal package repository, I generally recommend that you build native packages for your target platform(s), and use the package resource to manage them, rather than building from source. I know that is not always available or feasible, so …

The method which you make a “./configure && make && make install” style installation script idempotent depends on the kind of software you’re working with. Most often, it is sufficient to check for the target file’s existence. Sometimes, it is desirable to determine what version is required, and which version the program will output when executed with the proper command-line option. I will use your resource above as a starting point for these examples. Note that you can use bash as a shortcut for script resources that have interpreter bash.

Assumptions: The program is installed to /usr/local/bin/program and takes an argument --version presumably to display the version number. I put the cd, configure, and make commands together with && because presumably if one fails we shouldn’t attempt to continue execution.

bash "install_program" do
  not_if "/usr/local/bin/program --version | grep -q '#{node[:program][:version]}'"
  user "root"
  cwd "/tmp"
  code <<-EOH
    wget http://www.example.com/program-#{node[:program][:version]}.tar.gz -O /tmp/program-#{node[:program][:version]}.tar.gz
    tar -zxf program-#{node[:program][:version]}.tar.gz
    (cd program-#{node[:program][:version]}/ && ./configure && make && make install)
  EOH
end

Instead of using wget it is a bit better to use the remote_file resource as this is idempotent on its own. Note that the checksum parameter is added, with the value as an attribute. This parameter tells Chef not to download the remote file if the local target file matches the checksum. This is a SHA256 checksum. Also, this resource will notify the script to run immediately, so after it is downloaded. The script is set with action :nothing so it only gets executed if the remote_file is downloaded.

remote_file "/tmp/program-#{node[:program][:version]}.tar.gz" do
  source "http://www.example.com/program-#{node[:program][:version]}.tar.gz"
  checksum node[:program][:checksum]
  notifies :run, "bash[install_program]", :immediately
end

bash "install_program" do
  user "root"
  cwd "/tmp"
  code <<-EOH
    tar -zxf program-#{node[:program][:version]}.tar.gz
    (cd program-#{node[:program][:version]}/ && ./configure && make && make install)
  EOH
  action :nothing
end

Also, /tmp may be erased on your system upon reboot. It is recommended that you download to another location that isn’t deleted, such as Chef’s file cache location, which is the value of Chef::Config[:file_cache_path]. For example:

remote_file "#{Chef::Config[:file_cache_path]}/program.tar.gz" do
  ...
end

For further examples, you can see “source” recipes in several cookbooks shared by Opscode here: http://github.com/opscode/cookbooks. php, python, gnu_parallel, and nagios cookbooks all have “source” recipes.