String parsing via ruby (chef) - ruby

Question

Need to do install on centos 6 logrotate 3.8.7 out of sources, via chef.
Using simple execute. But also need to check for existing installation. How can I do that thing, if I can't parse logrotate --version output.
logrotate --version | tr -cd [:digit:]
&
logrotate --version | tr -d "logrotate"
and awk - no use..
Even if I don't parse output, chef can't compare it with my variable..
My recipe is:
ver = `logrotate --version`
if ver.eql? "logrotate 3.8.7"
puts "nothing to do"
else
bash "logrotate-source-install" do
user "root"
group "root"
cwd "/tmp"
code <<-EOH
cd /tmp
yum -y install gettext popt-devel
wget https://fedorahosted.org/releases/l/o/logrotate/logrotate-3.8.7.tar.gz
tar xf logrotate-3.8.7.tar.gz
cd logrotate-3.8.7
gmake
gmake install
EOH
end
end
Thx in advance.
Upd.
actual_ver = `logrotate --version 2>&1 | awk '{print $2}'`
ver = "3.8.7"
if actual_ver == ver
puts "nothing to do"
else
bash "logrotate-source-install" do ...
Parsing done, but chef can't recognize output..

Answer 1

You could use attribute only_if to guard this resource for idempotence.
Also, good idea would be to pull version to node attribute like:
default['logrotate']['version'] = '3.8.7'
and then use it in recepie:
version = default['logrotate']['version']
bash "logrotate-source-install" do
user "root"
group "root"
cwd "/tmp"
code <<-EOH
yum -y install gettext popt-devel
wget https://fedorahosted.org/releases/l/o/logrotate/logrotate-#{version}.tar.gz
tar xf logrotate-#{version}.tar.gz
cd logrotate-#{version}
gmake
gmake install
EOH
not_if "[ ${version} = \"$(logrotate --version 2>&1 | awk '{print $2}')\" ]"
end

Answer 2

Better version of this:
bash "logrotate-source-install" do
user "root"
group "root"
cwd "/tmp"
code <<-EOH
cd /tmp
yum -y install gettext popt-devel
wget https://fedorahosted.org/releases/l/o/logrotate/logrotate-3.8.7.tar.gz
tar xf logrotate-3.8.7.tar.gz
cd logrotate-3.8.7
gmake
gmake install
EOH
only_if do
version = shell_out('logrotate --version')
version.error? || version.stdout.split.last != '3.8.7'
end
end
This uses the only_if guard clause to control if the resource converges or not, and uses the shell_out helper instead of Ruby's shell execute syntax. This will be more widely portable, automatically splits stdout and stderr, and will correctly run the install if the command fails. Also doesn't depend on awk.

Answer 3

String parsing via ruby do the thing:
actual_ver = `logrotate --version 2>&1 | awk '{print $2}'`
ver = "387"
if actual_ver.delete('^0-9') == ver
puts "nothing to do"
else
bash "logrotate-source-install" do
user "root"
group "root"
cwd "/tmp"
code <<-EOH
cd /tmp
yum -y install gettext popt-devel
wget https://fedorahosted.org/releases/l/o/logrotate/logrotate-3.8.7.tar.gz
tar xf logrotate-3.8.7.tar.gz
cd logrotate-3.8.7
gmake
gmake install
EOH
end
end