preflight checks: refactor and fix aos_version

Bring in openshift_repos to provide Origin repo before checks on Origin.

For OCP we want the check to fail if both version 3.3 and version 3.4
are available - they shouldn't have both channels enabled.
For Origin everything is in one repo so it's not surprising to find 1.4
and 1.5 versions available.

Added unit tests as well.

1 files changed, 161 insertions, 53 deletions

diff --git a/roles/openshift_health_checker/library/aos_version.py b/roles/openshift_health_checker/library/aos_version.py
index 191a4b107..a46589443 100755
--- a/roles/openshift_health_checker/library/aos_version.py
+++ b/roles/openshift_health_checker/library/aos_version.py
@@ -1,91 +1,199 @@
 #!/usr/bin/python
 # vim: expandtab:tabstop=4:shiftwidth=4
 '''
-Ansible module for determining if multiple versions of an OpenShift package are
-available, and if the version requested is available down to the given
-precision.
-
-Multiple versions available suggest that multiple repos are enabled for the
-different versions, which may cause installation problems.
+Ansible module for yum-based systems determining if multiple releases
+of an OpenShift package are available, and if the release requested
+(if any) is available down to the given precision.
+
+For Enterprise, multiple releases available suggest that multiple repos
+are enabled for the different releases, which may cause installation
+problems. With Origin, however, this is a normal state of affairs as
+all the releases are provided in a single repo with the expectation that
+only the latest can be installed.
+
+Code in the openshift_version role contains a lot of logic to pin down
+the exact package and image version to use and so does some validation
+of release availability already. Without duplicating all that, we would
+like the user to have a helpful error message if we detect things will
+not work out right. Note that if openshift_release is not specified in
+the inventory, the version comparison checks just pass.
+
+TODO: fail gracefully on non-yum systems (dnf in Fedora)
 '''
 
-import yum  # pylint: disable=import-error
-
 from ansible.module_utils.basic import AnsibleModule
 
+IMPORT_EXCEPTION = None
+try:
+    import yum  # pylint: disable=import-error
+except ImportError as err:
+    IMPORT_EXCEPTION = err  # in tox test env, yum import fails
+
 
-def main():  # pylint: disable=missing-docstring,too-many-branches
+class AosVersionException(Exception):
+    '''Base exception class for package version problems'''
+    def __init__(self, message, problem_pkgs=None):
+        Exception.__init__(self, message)
+        self.problem_pkgs = problem_pkgs
+
+
+def main():
+    '''Entrypoint for this Ansible module'''
     module = AnsibleModule(
         argument_spec=dict(
-            prefix=dict(required=True),  # atomic-openshift, origin, ...
-            version=dict(required=True),
+            requested_openshift_release=dict(type="str", default=''),
+            openshift_deployment_type=dict(required=True),
+            rpm_prefix=dict(required=True),  # atomic-openshift, origin, ...?
         ),
         supports_check_mode=True
     )
 
-    def bail(error):  # pylint: disable=missing-docstring
-        module.fail_json(msg=error)
-
-    rpm_prefix = module.params['prefix']
+    if IMPORT_EXCEPTION:
+        module.fail_json(msg="aos_version module could not import yum: %s" % IMPORT_EXCEPTION)
 
+    # determine the packages we will look for
+    rpm_prefix = module.params['rpm_prefix']
     if not rpm_prefix:
-        bail("prefix must not be empty")
-
-    yb = yum.YumBase()  # pylint: disable=invalid-name
-    yb.conf.disable_excludes = ["all"]  # assume the openshift excluder will be managed, ignore current state
-
-    # search for package versions available for aos pkgs
-    expected_pkgs = [
+        module.fail_json(msg="rpm_prefix must not be empty")
+    expected_pkgs = set([
         rpm_prefix,
         rpm_prefix + '-master',
         rpm_prefix + '-node',
-    ]
+    ])
+
+    # determine what level of precision the user specified for the openshift version.
+    # should look like a version string with possibly many segments e.g. "3.4.1":
+    requested_openshift_release = module.params['requested_openshift_release']
+
+    # get the list of packages available and complain if anything is wrong
+    try:
+        pkgs = _retrieve_available_packages(expected_pkgs)
+        if requested_openshift_release:
+            _check_precise_version_found(pkgs, expected_pkgs, requested_openshift_release)
+            _check_higher_version_found(pkgs, expected_pkgs, requested_openshift_release)
+        if module.params['openshift_deployment_type'] in ['openshift-enterprise']:
+            _check_multi_minor_release(pkgs, expected_pkgs)
+    except AosVersionException as excinfo:
+        module.fail_json(msg=str(excinfo))
+    module.exit_json(changed=False)
+
+
+def _retrieve_available_packages(expected_pkgs):
+    # search for package versions available for openshift pkgs
+    yb = yum.YumBase()  # pylint: disable=invalid-name
+
+    # The openshift excluder prevents unintended updates to openshift
+    # packages by setting yum excludes on those packages. See:
+    # https://wiki.centos.org/SpecialInterestGroup/PaaS/OpenShift-Origin-Control-Updates
+    # Excludes are then disabled during an install or upgrade, but
+    # this check will most likely be running outside either. When we
+    # attempt to determine what packages are available via yum they may
+    # be excluded. So, for our purposes here, disable excludes to see
+    # what will really be available during an install or upgrade.
+    yb.conf.disable_excludes = ['all']
+
     try:
         pkgs = yb.pkgSack.returnPackages(patterns=expected_pkgs)
-    except yum.Errors.PackageSackError as e:  # pylint: disable=invalid-name
+    except yum.Errors.PackageSackError as excinfo:
         # you only hit this if *none* of the packages are available
-        bail('Unable to find any OpenShift packages.\nCheck your subscription and repo settings.\n%s' % e)
+        raise AosVersionException('\n'.join([
+            'Unable to find any OpenShift packages.',
+            'Check your subscription and repo settings.',
+            str(excinfo),
+        ]))
+    return pkgs
 
-    # determine what level of precision we're expecting for the version
-    expected_version = module.params['version']
-    if expected_version.startswith('v'):  # v3.3 => 3.3
-        expected_version = expected_version[1:]
-    num_dots = expected_version.count('.')
 
-    pkgs_by_name_version = {}
+class PreciseVersionNotFound(AosVersionException):
+    '''Exception for reporting packages not available at given release'''
+    def __init__(self, requested_release, not_found):
+        msg = ['Not all of the required packages are available at requested version %s:' % requested_release]
+        msg += ['  ' + name for name in not_found]
+        msg += ['Please check your subscriptions and enabled repositories.']
+        AosVersionException.__init__(self, '\n'.join(msg), not_found)
+
+
+def _check_precise_version_found(pkgs, expected_pkgs, requested_openshift_release):
+    # see if any packages couldn't be found at requested release version
+    # we would like to verify that the latest available pkgs have however specific a version is given.
+    # so e.g. if there is a package version 3.4.1.5 the check passes; if only 3.4.0, it fails.
+
     pkgs_precise_version_found = {}
     for pkg in pkgs:
-        # get expected version precision
-        match_version = '.'.join(pkg.version.split('.')[:num_dots + 1])
-        if match_version == expected_version:
+        if pkg.name not in expected_pkgs:
+            continue
+        # does the version match, to the precision requested?
+        # and, is it strictly greater, at the precision requested?
+        match_version = '.'.join(pkg.version.split('.')[:requested_openshift_release.count('.') + 1])
+        if match_version == requested_openshift_release:
             pkgs_precise_version_found[pkg.name] = True
-        # get x.y version precision
-        minor_version = '.'.join(pkg.version.split('.')[:2])
-        if pkg.name not in pkgs_by_name_version:
-            pkgs_by_name_version[pkg.name] = {}
-        pkgs_by_name_version[pkg.name][minor_version] = True
 
-    # see if any packages couldn't be found at requested version
-    # see if any packages are available in more than one minor version
     not_found = []
-    multi_found = []
     for name in expected_pkgs:
         if name not in pkgs_precise_version_found:
             not_found.append(name)
+
+    if not_found:
+        raise PreciseVersionNotFound(requested_openshift_release, not_found)
+
+
+class FoundHigherVersion(AosVersionException):
+    '''Exception for reporting that a higher version than requested is available'''
+    def __init__(self, requested_release, higher_found):
+        msg = ['Some required package(s) are available at a version',
+               'that is higher than requested %s:' % requested_release]
+        msg += ['  ' + name for name in higher_found]
+        msg += ['This will prevent installing the version you requested.']
+        msg += ['Please check your enabled repositories or adjust openshift_release.']
+        AosVersionException.__init__(self, '\n'.join(msg), higher_found)
+
+
+def _check_higher_version_found(pkgs, expected_pkgs, requested_openshift_release):
+    req_release_arr = [int(segment) for segment in requested_openshift_release.split(".")]
+    # see if any packages are available in a version higher than requested
+    higher_version_for_pkg = {}
+    for pkg in pkgs:
+        if pkg.name not in expected_pkgs:
+            continue
+        version = [int(segment) for segment in pkg.version.split(".")]
+        too_high = version[:len(req_release_arr)] > req_release_arr
+        higher_than_seen = version > higher_version_for_pkg.get(pkg.name, [])
+        if too_high and higher_than_seen:
+            higher_version_for_pkg[pkg.name] = version
+
+    if higher_version_for_pkg:
+        higher_found = []
+        for name, version in higher_version_for_pkg.items():
+            higher_found.append(name + '-' + '.'.join(str(segment) for segment in version))
+        raise FoundHigherVersion(requested_openshift_release, higher_found)
+
+
+class FoundMultiRelease(AosVersionException):
+    '''Exception for reporting multiple minor releases found for same package'''
+    def __init__(self, multi_found):
+        msg = ['Multiple minor versions of these packages are available']
+        msg += ['  ' + name for name in multi_found]
+        msg += ["There should only be one OpenShift release repository enabled at a time."]
+        AosVersionException.__init__(self, '\n'.join(msg), multi_found)
+
+
+def _check_multi_minor_release(pkgs, expected_pkgs):
+    # see if any packages are available in more than one minor version
+    pkgs_by_name_version = {}
+    for pkg in pkgs:
+        # keep track of x.y (minor release) versions seen
+        minor_release = '.'.join(pkg.version.split('.')[:2])
+        if pkg.name not in pkgs_by_name_version:
+            pkgs_by_name_version[pkg.name] = {}
+        pkgs_by_name_version[pkg.name][minor_release] = True
+
+    multi_found = []
+    for name in expected_pkgs:
         if name in pkgs_by_name_version and len(pkgs_by_name_version[name]) > 1:
             multi_found.append(name)
-    if not_found:
-        msg = 'Not all of the required packages are available at requested version %s:\n' % expected_version
-        for name in not_found:
-            msg += '  %s\n' % name
-        bail(msg + 'Please check your subscriptions and enabled repositories.')
-    if multi_found:
-        msg = 'Multiple minor versions of these packages are available\n'
-        for name in multi_found:
-            msg += '  %s\n' % name
-        bail(msg + "There should only be one OpenShift version's repository enabled at a time.")
 
-    module.exit_json(changed=False)
+    if multi_found:
+        raise FoundMultiRelease(multi_found)
 
 
 if __name__ == '__main__':