summaryrefslogtreecommitdiffstats
path: root/src/pybind/mgr/insights/health.py
blob: 1deb5d3a611889bbc876b9aca888f0036d41fb16 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
import json
from collections import defaultdict
import datetime

# freq to write cached state to disk
PERSIST_PERIOD = datetime.timedelta(seconds=10)
# on disk key prefix
HEALTH_HISTORY_KEY_PREFIX = "health_history/"
# apply on offset to "now": used for testing
NOW_OFFSET = None


class HealthEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, set):
            return list(obj)
        return json.JSONEncoder.default(self, obj)


class HealthCheckAccumulator(object):
    """
    Deuplicated storage of health checks.
    """

    def __init__(self, init_checks=None):
        # check : severity : { summary, detail }
        # summary and detail are deduplicated
        self._checks = defaultdict(lambda:
                                   defaultdict(lambda: {
                                       "summary": set(),
                                       "detail": set()
                                   }))

        if init_checks:
            self._update(init_checks)

    def __str__(self):
        return "check count {}".format(len(self._checks))

    def add(self, checks):
        """
        Add health checks to the current state

        Returns:
            bool: True if the state changed, False otherwise.
        """
        changed = False

        for check, info in checks.items():

            # only keep the icky stuff
            severity = info["severity"]
            if severity == "HEALTH_OK":
                continue

            summary = info["summary"]["message"]
            details = map(lambda d: d["message"], info["detail"])

            if self._add_check(check, severity, [summary], details):
                changed = True

        return changed

    def checks(self):
        return self._checks

    def merge(self, other):
        assert isinstance(other, HealthCheckAccumulator)
        self._update(other._checks)

    def _update(self, checks):
        """Merge checks with same structure. Does not set dirty bit"""
        for check in checks:
            for severity in checks[check]:
                summaries = set(checks[check][severity]["summary"])
                details = set(checks[check][severity]["detail"])
                self._add_check(check, severity, summaries, details)

    def _add_check(self, check, severity, summaries, details):
        changed = False

        for summary in summaries:
            if summary not in self._checks[check][severity]["summary"]:
                changed = True
                self._checks[check][severity]["summary"].add(summary)

        for detail in details:
            if detail not in self._checks[check][severity]["detail"]:
                changed = True
                self._checks[check][severity]["detail"].add(detail)

        return changed


class HealthHistorySlot(object):
    """
    Manage the life cycle of a health history time slot.

    A time slot is a fixed slice of wall clock time (e.g. every hours, from :00
    to :59), and all health updates that occur during this time are deduplicated
    together. A slot is initially in a clean state, and becomes dirty when a new
    health check is observed. The state of a slot should be persisted when
    need_flush returns true. Once the state has been flushed, reset the dirty
    bit by calling mark_flushed.
    """

    def __init__(self, init_health=dict()):
        self._checks = HealthCheckAccumulator(init_health.get("checks"))
        self._slot = self._curr_slot()
        self._next_flush = None

    def __str__(self):
        return "key {} next flush {} checks {}".format(
            self.key(), self._next_flush, self._checks)

    def health(self):
        return dict(checks=self._checks.checks())

    def key(self):
        """Identifier in the persist store"""
        return self._key(self._slot)

    def expired(self):
        """True if this slot is the current slot, False otherwise"""
        return self._slot != self._curr_slot()

    def need_flush(self):
        """True if this slot needs to be flushed, False otherwise"""
        now = HealthHistorySlot._now()
        if self._next_flush is not None:
            if self._next_flush <= now or self.expired():
                return True
        return False

    def mark_flushed(self):
        """Reset the dirty bit. Caller persists state"""
        assert self._next_flush
        self._next_flush = None

    def add(self, health):
        """
        Add health to the underlying health accumulator. When the slot
        transitions from clean to dirty a target flush time is computed.
        """
        changed = self._checks.add(health["checks"])
        if changed and not self._next_flush:
            self._next_flush = HealthHistorySlot._now() + PERSIST_PERIOD
        return changed

    def merge(self, other):
        assert isinstance(other, HealthHistorySlot)
        self._checks.merge(other._checks)

    @staticmethod
    def key_range(hours):
        """Return the time slot keys for the past N hours"""
        def inner(curr, hours):
            slot = curr - datetime.timedelta(hours=hours)
            return HealthHistorySlot._key(slot)
        curr = HealthHistorySlot._curr_slot()
        return map(lambda i: inner(curr, i), range(hours))

    @staticmethod
    def curr_key():
        """Key for the current UTC time slot"""
        return HealthHistorySlot._key(HealthHistorySlot._curr_slot())

    @staticmethod
    def key_to_time(key):
        """Return key converted into datetime"""
        timestr = key[len(HEALTH_HISTORY_KEY_PREFIX):]
        return datetime.datetime.strptime(timestr, "%Y-%m-%d_%H")

    @staticmethod
    def _key(dt):
        """Key format. Example: health_2018_11_05_00"""
        return HEALTH_HISTORY_KEY_PREFIX + dt.strftime("%Y-%m-%d_%H")

    @staticmethod
    def _now():
        """Control now time for easier testing"""
        now = datetime.datetime.utcnow()
        if NOW_OFFSET is not None:
            now = now + NOW_OFFSET
        return now

    @staticmethod
    def _curr_slot():
        """Slot for the current UTC time"""
        dt = HealthHistorySlot._now()
        return datetime.datetime(
            year=dt.year,
            month=dt.month,
            day=dt.day,
            hour=dt.hour)