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Server Roles: definitions of server roles and attributes

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This patch introduces classes which define the properties of server roles and
attributes and their relationship to LDAP attributes representing the
role/attribute.

A brief documentation about defining and using roles is given at the beginning
of the module.

http://www.freeipa.org/page/V4/Server_Roles
https://fedorahosted.org/freeipa/ticket/5181

Reviewed-By: Jan Cholasta <jcholast@redhat.com>
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Pavel Vomacka <pvomacka@redhat.com>
This commit is contained in:
Martin Babinsky 2016-05-26 19:24:22 +02:00 committed by Martin Basti
parent 0b11b36bf2
commit 7e2bef0b9f
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#
# Copyright (C) 2016 FreeIPA Contributors see COPYING for license
#
"""
This module contains the set of classes which abstract various bits and pieces
of information present in the LDAP tree about functionalities such as DNS
server, Active Directory trust controller etc. These properties come in two
distinct groups:
server roles
this group represents a genral functionality provided by one or more
IPA servers, such as DNS server, certificate authority and such. In
this case there is a many-to-many mapping between the roles and the
masters which provide them.
server attributes
these represent a functionality associated with the whole topology,
such as CA renewal master or DNSSec key master.
See the corresponding design page (http://www.freeipa.org/page/V4/Server_Roles)
for more info.
Both of these groups use `LDAPBasedProperty` class as a base.
Server Roles
============
Server role objects are usually consuming information from the master's service
container (cn=FQDN,cn=masters,cn=ipa,cn=etc,$SUFFIX) are represented by
`ServiceBasedRole`class. To create an instance of such role, you only need to
specify role name and individual services comprising the role (more systemd
services may be enabled to provide some function):
>>> example_role = ServiceBasedRole(
... "Example Role",
... component_services = ['SERVICE1', 'SERVICE2'])
>>> example_role.name
'Example Role'
The role object can then be queried for the status of the role in the whole
topology or on a single master by using its `status` method. This method
returns a list of dictionaries akin to LDAP entries comprised from server name,
role name and role status (enabled if role is enabled, configured if the
service entries are present but not marked as enabled by 'enabledService'
config string, absent if the service entries are not present).
Note that 'AD trust agent' role is based on membership of the master in the
'adtrust agents' sysaccount group and is thus an instance of different class
(`ADTrustBasedRole`). This role also does not have 'configured' status, since
the master is either member of the group ('enabled') or not ('absent')
Server Attributes
=================
Server attributes are implemented as instances of `ServerAttribute` class. The
attribute is defined by some flag set on 'ipaConfigString' attribute of some
service entry. To create your own server attribute, see the following example:
>>> example_attribute = ServerAttribute("Example Attribute", example_role,
... "SERVICE1", "roleMaster")
>>> example_attribute.name
'Example Attribute'
The FQDN of master with the attribute set can be requested using `get()`
method. The attribute master can be changed by the `set()` method
which accepts FQDN of a new master hosting the attribute.
The available role/attribute instances are stored in
`role_instances`/`attribute_instances` tuples.
"""
import abc
from collections import namedtuple, defaultdict
from ldap import SCOPE_ONELEVEL
import six
from ipalib import _, errors
from ipapython.dn import DN
if six.PY3:
unicode = str
ENABLED = u'enabled'
CONFIGURED = u'configured'
ABSENT = u'absent'
@six.add_metaclass(abc.ABCMeta)
class LDAPBasedProperty(object):
"""
base class for all master properties defined by LDAP content
:param attr_name: attribute name
:param name: user-friendly name of the property
:param attrs_list: list of attributes to retrieve during search, defaults
to all
"""
def __init__(self, attr_name, name):
self.attr_name = attr_name
self.name = name
@six.add_metaclass(abc.ABCMeta)
class BaseServerRole(LDAPBasedProperty):
"""
Server role hierarchy apex. All other server role definition should either
inherit from it or at least provide the 'status' method for querying role
status
property
"""
def create_role_status_dict(self, server, status):
"""
the output of `status()` method should be a list of dictionaries having
the following keys:
* role_servrole: name of role
* server_server: server FQDN
* status: role status on server
this methods returns such a dict given server and role status
"""
return {
u'role_servrole': self.name,
u'server_server': server,
u'status': status}
@abc.abstractmethod
def create_search_params(self, ldap, api_instance, server=None):
"""
create search base and filter
:param ldap: ldap connection
:param api_instance: API instance
:param server: server FQDN. if given, the method should generate
filter and search base matching only the status on this server
:returns: tuple of search base (a DN) and search filter
"""
pass
@abc.abstractmethod
def get_result_from_entries(self, entries):
"""
Get role status from returned LDAP entries
:param entries: LDAPEntry objects returned by `search()`
:returns: list of dicts generated by `create_role_status_dict()`
method
"""
pass
def _fill_in_absent_masters(self, ldap2, api_instance, result):
"""
get all masters on which the role is absent
:param ldap2: LDAP connection
:param api_instance: API instance
:param result: output of `get_result_from_entries` method
:returns: list of masters on which the role is absent
"""
search_base = DN(api_instance.env.container_masters,
api_instance.env.basedn)
search_filter = '(objectclass=ipaConfigObject)'
attrs_list = ['cn']
all_masters = ldap2.get_entries(
search_base,
filter=search_filter,
scope=SCOPE_ONELEVEL,
attrs_list=attrs_list)
all_master_cns = set(m['cn'][0] for m in all_masters)
enabled_configured_masters = set(r[u'server_server'] for r in result)
absent_masters = all_master_cns.difference(enabled_configured_masters)
return [self.create_role_status_dict(m, ABSENT) for m in
absent_masters]
def status(self, api_instance, server=None, attrs_list=("*",)):
"""
probe and return status of the role either on single server or on the
whole topology
:param api_instance: API instance
:param server: server FQDN. If given, only the status of the role on
this master will be returned
:returns: * 'enabled' if the role is enabled on the master
* 'configured' if it is not enabled but has
been configured by installer
* 'absent' otherwise
"""
ldap2 = api_instance.Backend.ldap2
search_base, search_filter = self.create_search_params(
ldap2, api_instance, server=server)
try:
entries = ldap2.get_entries(
search_base,
filter=search_filter,
attrs_list=attrs_list)
except errors.EmptyResult:
entries = []
if not entries and server is not None:
return [self.create_role_status_dict(server, ABSENT)]
result = self.get_result_from_entries(entries)
if server is None:
result.extend(
self._fill_in_absent_masters(ldap2, api_instance, result))
return sorted(result, key=lambda x: x[u'server_server'])
class ServerAttribute(LDAPBasedProperty):
"""
Class from which server attributes should be instantiated
:param associated_role_name: name of a role which must be enabled
on the provider
:param associated_service_name: name of LDAP service on which the
attribute is set. Does not need to belong to the service entries
of associate role
:param ipa_config_string_value: value of `ipaConfigString` attribute
associated with the presence of server attribute
"""
def __init__(self, attr_name, name, associated_role_name,
associated_service_name,
ipa_config_string_value):
super(ServerAttribute, self).__init__(attr_name, name)
self.associated_role_name = associated_role_name
self.associated_service_name = associated_service_name
self.ipa_config_string_value = ipa_config_string_value
@property
def associated_role(self):
for inst in role_instances:
if self.associated_role_name == inst.attr_name:
return inst
raise NotImplementedError(
"{}: no valid associated role found".format(self.attr_name))
def create_search_filter(self, ldap):
"""
Create search filter which matches LDAP data corresponding to the
attribute
"""
svc_filter = ldap.make_filter_from_attr(
'cn', self.associated_service_name)
configstring_filter = ldap.make_filter_from_attr(
'ipaConfigString', self.ipa_config_string_value)
return ldap.combine_filters(
[svc_filter, configstring_filter], rules=ldap.MATCH_ALL)
def get(self, api_instance):
"""
get the master which has the attribute set
:param api_instance: API instance
:returns: master FQDN
"""
ldap2 = api_instance.Backend.ldap2
search_base = DN(api_instance.env.container_masters,
api_instance.env.basedn)
search_filter = self.create_search_filter(ldap2)
try:
entries = ldap2.get_entries(search_base, filter=search_filter)
except errors.EmptyResult:
return
master_cn = entries[0].dn[1]['cn']
associated_role_providers = set(
self._get_assoc_role_providers(api_instance))
if master_cn not in associated_role_providers:
raise errors.ValidationError(
name=self.name,
error=_("all masters must have %(role)s role enabled" %
{'role': self.associated_role.name})
)
return master_cn
def _get_master_dn(self, api_instance, server):
return DN(('cn', server), api_instance.env.container_masters,
api_instance.env.basedn)
def _get_masters_service_entry(self, ldap, master_dn):
service_dn = DN(('cn', self.associated_service_name), master_dn)
return ldap.get_entry(service_dn)
def _add_attribute_to_svc_entry(self, ldap, service_entry):
"""
add the server attribute to the entry of associated service
:param ldap: LDAP connection object
:param service_entry: associated service entry
"""
ipa_config_string = service_entry.get('ipaConfigString', [])
ipa_config_string.append(self.ipa_config_string_value)
service_entry['ipaConfigString'] = ipa_config_string
ldap.update_entry(service_entry)
def _remove_attribute_from_svc_entry(self, ldap, service_entry):
"""
remove the server attribute to the entry of associated service
single ipaConfigString attribute is case-insensitive, we must handle
arbitrary case of target value
:param ldap: LDAP connection object
:param service_entry: associated service entry
"""
ipa_config_string = service_entry.get('ipaConfigString', [])
for value in ipa_config_string:
if value.lower() == self.ipa_config_string_value.lower():
service_entry['ipaConfigString'].remove(value)
ldap.update_entry(service_entry)
def _get_assoc_role_providers(self, api_instance):
"""
get list of all servers on which the associated role is enabled
"""
return [
r[u'server_server'] for r in self.associated_role.status(
api_instance) if r[u'status'] == ENABLED]
def _remove(self, api_instance, master):
"""
remove attribute from the master
:param api_instance: API instance
:param master: master FQDN
"""
ldap = api_instance.Backend.ldap2
master_dn = self._get_master_dn(api_instance, master)
service_entry = self._get_masters_service_entry(ldap, master_dn)
self._remove_attribute_from_svc_entry(ldap, service_entry)
def _add(self, api_instance, master):
"""
add attribute to the master
:param api_instance: API instance
:param master: master FQDN
:raises: * errors.ValidationError if the associated role is not enabled
on the master
"""
assoc_role_providers = self._get_assoc_role_providers(api_instance)
ldap = api_instance.Backend.ldap2
if master not in assoc_role_providers:
raise errors.ValidationError(
name=master,
error=_("must have %(role)s role enabled" %
{'role': self.associated_role.name})
)
master_dn = self._get_master_dn(api_instance, master)
service_entry = self._get_masters_service_entry(ldap, master_dn)
self._add_attribute_to_svc_entry(ldap, service_entry)
def set(self, api_instance, master):
"""
set the attribute on master
:param api_instance: API instance
:param master: FQDN of the new master
the attribute is automatically unset from previous master if present
:raises: errors.EmptyModlist if the new masters is the same as
the original on
"""
old_master = self.get(api_instance)
if old_master == master:
raise errors.EmptyModlist
self._add(api_instance, master)
if old_master is not None:
self._remove(api_instance, old_master)
_Service = namedtuple('Service', ['name', 'enabled'])
class ServiceBasedRole(BaseServerRole):
"""
class for all role instances whose status is defined by presence of one or
more entries in LDAP and/or their attributes
"""
def __init__(self, attr_name, name, component_services):
super(ServiceBasedRole, self).__init__(attr_name, name)
self.component_services = component_services
def _validate_component_services(self, services):
svc_set = {s.name for s in services}
if svc_set != set(self.component_services):
raise ValueError(
"{}: Mismatch between component services and search result "
"(expected: {}, got: {})".format(
self.__class__.__name__,
', '.join(sorted(self.component_services)),
', '.join(sorted(s.name for s in services))))
def _get_service(self, entry):
entry_cn = entry['cn'][0]
enabled = self._is_service_enabled(entry)
return _Service(name=entry_cn, enabled=enabled)
def _is_service_enabled(self, entry):
"""
determine whether the service is enabled based on the presence of
enabledService attribute in ipaConfigString attribute.
Since the attribute is case-insensitive, we must first lowercase its
values and do the comparison afterwards.
:param entry: LDAPEntry of the service
:returns: True if the service entry is enabled, False otherwise
"""
enabled_value = 'enabledservice'
ipaconfigstring_values = set(
e.lower() for e in entry.get('ipaConfigString', []))
return enabled_value in ipaconfigstring_values
def _get_services_by_masters(self, entries):
"""
given list of entries, return a dictionary keyed by master FQDNs which
contains list of service entries belonging to the master
"""
services_by_master = defaultdict(list)
for e in entries:
service = self._get_service(e)
master_cn = e.dn[1]['cn']
services_by_master[master_cn].append(service)
return services_by_master
def get_result_from_entries(self, entries):
result = []
services_by_master = self._get_services_by_masters(entries)
for master, services in services_by_master.items():
try:
self._validate_component_services(services)
except ValueError:
continue
status = (
ENABLED if all(s.enabled for s in services) else
CONFIGURED)
result.append(self.create_role_status_dict(master, status))
return result
def create_search_params(self, ldap, api_instance, server=None):
search_base = DN(api_instance.env.container_masters,
api_instance.env.basedn)
search_filter = ldap.make_filter_from_attr(
'cn',
self.component_services,
rules=ldap.MATCH_ANY,
exact=True
)
if server is not None:
search_base = DN(('cn', server), search_base)
return search_base, search_filter
def status(self, api_instance, server=None):
return super(ServiceBasedRole, self).status(
api_instance, server=server, attrs_list=('ipaConfigString', 'cn'))
class ADtrustBasedRole(BaseServerRole):
"""
Class which should instantiate roles besed on membership in 'adtrust agent'
sysaccount group.
"""
def get_result_from_entries(self, entries):
result = []
for e in entries:
result.append(
self.create_role_status_dict(e['fqdn'][0], ENABLED)
)
return result
def create_search_params(self, ldap, api_instance, server=None):
search_base = DN(
api_instance.env.container_host, api_instance.env.basedn)
search_filter = ldap.make_filter_from_attr(
"memberof",
DN(('cn', 'adtrust agents'), ('cn', 'sysaccounts'),
('cn', 'etc'), api_instance.env.basedn)
)
if server is not None:
server_filter = ldap.make_filter_from_attr(
'fqdn',
server,
exact=True
)
search_filter = ldap.combine_filters(
[search_filter, server_filter],
rules=ldap.MATCH_ALL
)
return search_base, search_filter
role_instances = (
ADtrustBasedRole(u"ad_trust_agent_server", u"AD trust agent"),
ServiceBasedRole(
u"ad_trust_controller_server",
u"AD trust controller",
component_services=['ADTRUST']
),
ServiceBasedRole(
u"ca_server_server",
u"CA server",
component_services=['CA']
),
ServiceBasedRole(
u"dns_server_server",
u"DNS server",
component_services=['DNS', 'DNSKeySync']
),
ServiceBasedRole(
u"ipa_master_server",
u"IPA master",
component_services=['HTTP', 'KDC', 'KPASSWD']
),
ServiceBasedRole(
u"kra_server_server",
u"KRA server",
component_services=['KRA']
),
)
attribute_instances = (
ServerAttribute(
u"ca_renewal_master_server",
u"CA renewal master",
u"ca_server_server",
u"CA",
u"caRenewalMaster",
),
ServerAttribute(
u"dnssec_key_master_server",
u"DNSSec key master",
u"dns_server_server",
u"DNSSEC",
u"dnssecKeyMaster",
),
)