fix(pip): add pre_release parameter and filter latest_version

Author: teluq-pbrideau

manifests/pip.pp

@@ -70,6 +70,7 @@
   String[1]                                         $log_dir        = '/tmp',
   Array[String]                                     $path           = ['/usr/local/bin','/usr/bin','/bin', '/usr/sbin'],
   String[1]                                         $exec_provider  = 'shell',
+  Boolean                                           $pre_release    = false,
 ) {
   $python_provider = getparam(Class['python'], 'provider')
   $python_version  = getparam(Class['python'], 'version')
@@ -133,6 +134,11 @@
     $install_editable = ''
   }
 
+  $prerelease_flag = $pre_release ? {
+    false   => '',
+    default => '--pre'
+  }
+
   # TODO: Do more robust argument checking, but below is a start
   if ($ensure == absent) and $install_args {
     fail('python::pip cannot provide install_args with ensure => absent')
@@ -179,7 +185,7 @@
     default                                                                   => "'${url}#egg=${egg_name}'",
   }
 
-  $pip_install     = "${pip_env} --log ${log}/pip.log install"
+  $pip_install     = "${pip_env} --log ${log}/pip.log install ${prerelease_flag}"
   $pip_common_args = "${pypi_index} ${pypi_extra_index} ${proxy_flag} ${install_editable} ${source}"
 
   # Explicit version out of VCS when PIP supported URL is provided
@@ -217,12 +223,21 @@
         # Unfortunately this is the smartest way of getting the latest available package version with pip as of now
         # Note: we DO need to repeat ourselves with "from version" in both grep and sed as on some systems pip returns
         # more than one line with paretheses.
-        $latest_version = join([
-            "${pip_install} ${legacy_resolver} ${pypi_index} ${pypi_extra_index} ${proxy_flag}",
-            " ${install_args} ${install_editable} ${real_pkgname}==notreallyaversion 2>&1",
-            " | sed -nE 's/.*\\(from versions: (.*, )*(.*)\\)/\\2/p'",
-            ' | tr -d "[:space:]"',
-        ])
+        # Public version identifiers: [N!]N(.N)*[{a|b|rc}N][.postN][.devN]
+        $latest_version = $pre_release ? {
+          false   => join([
+              "${pip_install} ${legacy_resolver} ${pypi_index} ${pypi_extra_index} ${proxy_flag}",
+              " ${install_args} ${install_editable} ${real_pkgname}==notreallyaversion 2>&1",
+              " | sed -nE 's/.*\\(from versions: ([^\\)]*)\\)/\\1/p'",
+              ' | awk \'BEGIN {RS=", "} {if ($0 !~ /(a|b|rc|dev)/) {gsub(/\n/,"");stable[arraylen++]=$0}} END {print stable[arraylen-1] }\'',
+          ]),
+          default => join([
+              "${pip_install} ${legacy_resolver} ${pypi_index} ${pypi_extra_index} ${proxy_flag}",
+              " ${install_args} ${install_editable} ${real_pkgname}==notreallyaversion 2>&1",
+              " | sed -nE 's/.*\\(from versions: (.*, )*(.*)\\)/\\2/p'",
+              ' | tr -d "[:space:]"',
+          ])
+        }
 
         # Packages with underscores in their names are listed with dashes in their place in `pip freeze` output
         $pkgname_with_dashes            = regsubst($real_pkgname, '_', '-', 'G')