added 'try' module

3 files changed, 67 insertions, 0 deletions

diff --git a/puppet/modules/try/README.md b/puppet/modules/try/README.md
new file mode 100644
index 00000000..3888661e
--- /dev/null
+++ b/puppet/modules/try/README.md
@@ -0,0 +1,13 @@
+This module provides a "try" wrapper around common resource types.
+
+For example:
+
+    try::file {
+      '/path/to/file':
+        ensure => 'link',
+        target => $target;
+    }
+
+This will work just like `file`, but will silently fail if `$target` is undefined or the file does not exist.
+
+So far, only `file` type with symlinks works.
diff --git a/puppet/modules/try/manifests/file.pp b/puppet/modules/try/manifests/file.pp
new file mode 100644
index 00000000..406c0b7a
--- /dev/null
+++ b/puppet/modules/try/manifests/file.pp
@@ -0,0 +1,51 @@
+#
+# like built-in type "file", but gets gracefully ignored if the target does not exist or is undefined.
+#
+# /bin/true and /usr/bin/test are hardcoded to their paths in debian.
+#
+
+define try::file (
+  $ensure = undef,
+  $target = undef,
+  $restore = true) {
+
+  if $target != undef {
+    exec { "check_${name}":
+      command => "/bin/true",
+      onlyif => "/usr/bin/test -e '${target}'",
+      loglevel => info;
+    }
+    file { "$name":
+      ensure => $ensure,
+      target => $target,
+      require => Exec["check_${name}"],
+      loglevel => info;
+    }
+  }
+
+  #
+  # if the target does not exist (or is undef), and the file happens to be in a git repo,
+  # then restore the file to its original state.
+  #
+  if $target == undef or $restore {
+    $file_basename = basename($name)
+    $file_dirname  = dirname($name)
+    $command = "git rev-parse && unlink '${name}'; git checkout -- '${file_basename}' && chown --reference='${file_dirname}' '${name}'; true"
+    debug($command)
+
+    if $target == undef {
+      exec { "restore_${name}":
+        command => $command,
+        cwd => $file_dirname,
+        loglevel => info;
+      }
+    } else {
+      exec { "restore_${name}":
+        unless => "/usr/bin/test -e '${target}'",
+        command => $command,
+        cwd => $file_dirname,
+        loglevel => info;
+      }
+    }
+  }
+}
diff --git a/puppet/modules/try/manifests/init.pp b/puppet/modules/try/manifests/init.pp
new file mode 100644
index 00000000..1d2108c9
--- /dev/null
+++ b/puppet/modules/try/manifests/init.pp
@@ -0,0 +1,3 @@
+class try {
+
+}