Add the ability to specify an install_dir to the gem module (#38195)

* Add the ability to specify an install_dir to the gem module

* Add GEM_HOME when installing a non-global gem

* Add tests for custom gem path

* Fix sanity tests

* Add changelog entry

* Rebase and add tests for incorrect options

Co-authored by: Antoine Catton <devel@antoine.catton.fr>

lib/ansible/modules/packaging/language/gem.py

@@ -58,6 +58,13 @@ options:
     - Override the path to the gem executable
     required: false
     version_added: "1.4"
+  install_dir:
+    description:
+    - Install the gems into a specific directory.
+      These gems will be independant from the global installed ones.
+      Specifying this requires user_install to be false.
+    required: false
+    version_added: "2.6"
   env_shebang:
     description:
       - Rewrite the shebang line on installed scripts to use /usr/bin/env.
@@ -133,6 +140,12 @@ def get_rubygems_version(module):
     return tuple(int(x) for x in match.groups())
 
 
+def get_rubygems_environ(module):
+    if module.params['install_dir']:
+        return {'GEM_HOME': module.params['install_dir']}
+    return None
+
+
 def get_installed_versions(module, remote=False):
 
     cmd = get_rubygems_path(module)
@@ -143,7 +156,9 @@ def get_installed_versions(module, remote=False):
             cmd.extend(['--source', module.params['repository']])
     cmd.append('-n')
     cmd.append('^%s$' % module.params['name'])
-    (rc, out, err) = module.run_command(cmd, check_rc=True)
+
+    environ = get_rubygems_environ(module)
+    (rc, out, err) = module.run_command(cmd, environ_update=environ, check_rc=True)
     installed_versions = []
     for line in out.splitlines():
         match = re.match(r"\S+\s+\((.+)\)", line)
@@ -155,7 +170,6 @@ def get_installed_versions(module, remote=False):
 
 
 def exists(module):
-
     if module.params['state'] == 'latest':
         remoteversions = get_installed_versions(module, remote=True)
         if remoteversions:
@@ -175,14 +189,18 @@ def uninstall(module):
     if module.check_mode:
         return
     cmd = get_rubygems_path(module)
+    environ = get_rubygems_environ(module)
     cmd.append('uninstall')
+    if module.params['install_dir']:
+        cmd.extend(['--install-dir', module.params['install_dir']])
+
     if module.params['version']:
         cmd.extend(['--version', module.params['version']])
     else:
         cmd.append('--all')
         cmd.append('--executable')
     cmd.append(module.params['name'])
-    module.run_command(cmd, check_rc=True)
+    module.run_command(cmd, environ_update=environ, check_rc=True)
 
 
 def install(module):
@@ -211,6 +229,8 @@ def install(module):
         cmd.append('--user-install')
     else:
         cmd.append('--no-user-install')
+    if module.params['install_dir']:
+        cmd.extend(['--install-dir', module.params['install_dir']])
     if module.params['pre_release']:
         cmd.append('--pre')
     if not module.params['include_doc']:
@@ -238,6 +258,7 @@ def main():
             repository=dict(required=False, aliases=['source'], type='str'),
             state=dict(required=False, default='present', choices=['present', 'absent', 'latest'], type='str'),
             user_install=dict(required=False, default=True, type='bool'),
+            install_dir=dict(required=False, type='path'),
             pre_release=dict(required=False, default=False, type='bool'),
             include_doc=dict(required=False, default=False, type='bool'),
             env_shebang=dict(required=False, default=False, type='bool'),
@@ -252,6 +273,8 @@ def main():
         module.fail_json(msg="Cannot specify version when state=latest")
     if module.params['gem_source'] and module.params['state'] == 'latest':
         module.fail_json(msg="Cannot maintain state=latest when installing from local source")
+    if module.params['user_install'] and module.params['install_dir']:
+        module.fail_json(msg="install_dir requires user_install=false")
 
     if not module.params['gem_source']:
         module.params['gem_source'] = module.params['name']