(Backport 50452, 54022) Add new module freezer

salt/modules/freezer.py

@@ -0,0 +1,298 @@
+# -*- coding: utf-8 -*-
+
+'''
+:maintainer:    Alberto Planas <aplanas@suse.com>
+:maturity:      new
+:depends:       None
+:platform:      Linux
+'''
+from __future__ import absolute_import, print_function, unicode_literals
+import logging
+import os
+
+from salt.exceptions import CommandExecutionError
+from salt.utils.args import clean_kwargs
+from salt.utils.files import fopen
+import salt.utils.json as json
+from salt.ext.six.moves import zip
+
+log = logging.getLogger(__name__)
+
+__func_alias__ = {
+    'list_': 'list',
+}
+
+
+def __virtual__():
+    '''
+    Freezer is based on top of the pkg module.
+
+    Return True since the `pkg` module should always exist. This
+    avoids the overhead of loading all modules.
+
+    '''
+    return True
+
+
+def _states_path():
+    '''
+    Return the path where we will store the states.
+    '''
+    return os.path.join(__opts__['cachedir'], 'freezer')
+
+
+def _paths(name=None):
+    '''
+    Return the full path for the packages and repository freezer
+    files.
+
+    '''
+    name = 'freezer' if not name else name
+    states_path = _states_path()
+    return (
+        os.path.join(states_path, '{}-pkgs.yml'.format(name)),
+        os.path.join(states_path, '{}-reps.yml'.format(name)),
+    )
+
+
+def status(name=None):
+    '''
+    Return True if there is already a frozen state.
+
+    A frozen state is merely a list of packages (including the
+    version) in a specific time. This information can be used to
+    compare with the current list of packages, and revert the
+    installation of some extra packages that are in the system.
+
+    name
+        Name of the frozen state. Optional.
+
+    CLI Example:
+
+    .. code-block:: bash
+
+        salt '*' freezer.status
+        salt '*' freezer.status pre_install
+
+    '''
+    name = 'freezer' if not name else name
+    return all(os.path.isfile(i) for i in _paths(name))
+
+
+def list_():
+    '''
+    Return the list of frozen states.
+
+    CLI Example:
+
+    .. code-block:: bash
+
+        salt '*' freezer.list
+
+    '''
+    ret = []
+    states_path = _states_path()
+    if not os.path.isdir(states_path):
+        return ret
+
+    for state in os.listdir(states_path):
+        if state.endswith(('-pkgs.yml', '-reps.yml')):
+            # Remove the suffix - both files start with the freezer
+            # name
+            ret.append(state[:-9])
+    return sorted(set(ret))
+
+
+def freeze(name=None, force=False, **kwargs):
+    '''
+    Save the list of package and repos in a freeze file.
+
+    As this module is build on top of the pkg module, the user can
+    send extra attributes to the underlying pkg module via kwargs.
+    This function will call ``pkg.list_pkgs`` and ``pkg.list_repos``,
+    and any additional arguments will be passed through to those
+    functions.
+
+    name
+        Name of the frozen state. Optional.
+
+    force
+        If true, overwrite the state. Optional.
+
+    CLI Example:
+
+    .. code-block:: bash
+
+        salt '*' freezer.freeze
+        salt '*' freezer.freeze pre_install
+        salt '*' freezer.freeze force=True root=/chroot
+
+    '''
+    states_path = _states_path()
+
+    try:
+        if not os.path.exists(states_path):
+            os.makedirs(states_path)
+    except OSError as e:
+        msg = 'Error when trying to create the freezer storage %s: %s'
+        log.error(msg, states_path, e)
+        raise CommandExecutionError(msg % (states_path, e))
+
+    if status(name) and not force:
+        raise CommandExecutionError('The state is already present. Use '
+                                    'force parameter to overwrite.')
+    safe_kwargs = clean_kwargs(**kwargs)
+    pkgs = __salt__['pkg.list_pkgs'](**safe_kwargs)
+    repos = __salt__['pkg.list_repos'](**safe_kwargs)
+    for fname, content in zip(_paths(name), (pkgs, repos)):
+        with fopen(fname, 'w') as fp:
+            json.dump(content, fp)
+    return True
+
+
+def _add_missing_repositories(frozen_repos, ret, **kwargs):
+    '''Add missing repositories and update the ret dict'''
+    repos = __salt__['pkg.list_repos'](**kwargs)
+    missing_repos = set(frozen_repos) - set(repos)
+    for repo in missing_repos:
+        try:
+            # In Python 2 we cannot do advance destructuring, so we
+            # need to create a temporary dictionary that will merge
+            # all the parameters
+            _tmp_kwargs = frozen_repos[repo].copy()
+            _tmp_kwargs.update(kwargs)
+            __salt__['pkg.mod_repo'](repo, **_tmp_kwargs)
+            ret['repos']['add'].append(repo)
+            log.info('Added missing repository %s', repo)
+        except Exception as e:
+            msg = 'Error adding %s repository: %s'
+            log.error(msg, repo, e)
+            ret['comment'].append(msg % (repo, e))
+
+
+def _remove_extra_repositories(frozen_repos, ret, **kwargs):
+    '''Remove extra repositories and update the ret dict'''
+    repos = __salt__['pkg.list_repos'](**kwargs)
+    extra_repos = set(repos) - set(frozen_repos)
+    for repo in extra_repos:
+        try:
+            __salt__['pkg.del_repo'](repo, **kwargs)
+            ret['repos']['remove'].append(repo)
+            log.info('Removed extra repository %s', repo)
+        except Exception as e:
+            msg = 'Error removing %s repository: %s'
+            log.error(msg, repo, e)
+            ret['comment'].append(msg % (repo, e))
+
+
+def _add_missing_packages(frozen_pkgs, ret, **kwargs):
+    '''Add missing packages and update the ret dict'''
+    # NOTE: we can remove the `for` using `pkgs`. This will improve
+    # performance, but I want to have a more detalied report of what
+    # packages are installed or failed.
+    pkgs = __salt__['pkg.list_pkgs'](**kwargs)
+    missing_pkgs = set(frozen_pkgs) - set(pkgs)
+    for pkg in missing_pkgs:
+        try:
+            __salt__['pkg.install'](name=pkg, **kwargs)
+            ret['pkgs']['add'].append(pkg)
+            log.info('Added missing package %s', pkg)
+        except Exception as e:
+            msg = 'Error adding %s package: %s'
+            log.error(msg, pkg, e)
+            ret['comment'].append(msg % (pkg, e))
+
+
+def _remove_extra_packages(frozen_pkgs, ret, **kwargs):
+    '''Remove extra packages and update the ret dict'''
+    pkgs = __salt__['pkg.list_pkgs'](**kwargs)
+    extra_pkgs = set(pkgs) - set(frozen_pkgs)
+    for pkg in extra_pkgs:
+        try:
+            __salt__['pkg.remove'](name=pkg, **kwargs)
+            ret['pkgs']['remove'].append(pkg)
+            log.info('Removed extra package %s', pkg)
+        except Exception as e:
+            msg = 'Error removing %s package: %s'
+            log.error(msg, pkg, e)
+            ret['comment'].append(msg % (pkg, e))
+
+
+def restore(name=None, clean=False, **kwargs):
+    '''
+    Make sure that the system contains the packages and repos from a
+    frozen state.
+
+    Read the list of packages and repositories from the freeze file,
+    and compare it with the current list of packages and repos. If
+    there is any difference, all the missing packages are repos will
+    be installed, and all the extra packages and repos will be
+    removed.
+
+    As this module is build on top of the pkg module, the user can
+    send extra attributes to the underlying pkg module via kwargs.
+    This function will call ``pkg.list_repos``, ``pkg.mod_repo``,
+    ``pkg.list_pkgs``, ``pkg.install``, ``pkg.remove`` and
+    ``pkg.del_repo``, and any additional arguments will be passed
+    through to those functions.
+
+    name
+        Name of the frozen state. Optional.
+
+    clean
+        If True remove the frozen information YAML from the cache
+
+        .. version-added:: Neon
+
+    CLI Example:
+
+    .. code-block:: bash
+
+        salt '*' freezer.restore
+        salt '*' freezer.restore root=/chroot
+
+    '''
+    if not status(name):
+        raise CommandExecutionError('Frozen state not found.')
+
+    frozen_pkgs = {}
+    frozen_repos = {}
+    for fname, content in zip(_paths(name), (frozen_pkgs, frozen_repos)):
+        with fopen(fname) as fp:
+            content.update(json.load(fp))
+
+    # The ordering of removing or adding packages and repos can be
+    # relevant, as maybe some missing package comes from a repo that
+    # is also missing, so it cannot be installed. But can also happend
+    # that a missing package comes from a repo that is present, but
+    # will be removed.
+    #
+    # So the proposed order is;
+    #   - Add missing repos
+    #   - Add missing packages
+    #   - Remove extra packages
+    #   - Remove extra repos
+
+    safe_kwargs = clean_kwargs(**kwargs)
+
+    # Note that we expect that the information stored in list_XXX
+    # match with the mod_XXX counterpart. If this is not the case the
+    # recovery will be partial.
+
+    ret = {
+        'pkgs': {'add': [], 'remove': []},
+        'repos': {'add': [], 'remove': []},
+        'comment': [],
+    }
+
+    _add_missing_repositories(frozen_repos, ret, **safe_kwargs)
+    _add_missing_packages(frozen_pkgs, ret, **safe_kwargs)
+    _remove_extra_packages(frozen_pkgs, ret, **safe_kwargs)
+    _remove_extra_repositories(frozen_repos, ret, **safe_kwargs)
+
+    # Clean the cached YAML files
+    if clean and not ret['comment']:
+        for fname in _paths(name):
+            os.remove(fname)
+
+    return ret