forked from prometheus-community/postgres_exporter
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathpostgres_exporter.go
1029 lines (912 loc) · 37.6 KB
/
postgres_exporter.go
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
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
package main
import (
"database/sql"
"errors"
"flag"
"fmt"
"io/ioutil"
"math"
"net/http"
"os"
"regexp"
"strconv"
"sync"
"time"
"gopkg.in/yaml.v2"
"github.com/blang/semver"
_ "github.com/lib/pq"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/log"
)
var Version string = "0.0.1"
var (
listenAddress = flag.String(
"web.listen-address", ":9187",
"Address to listen on for web interface and telemetry.",
)
metricPath = flag.String(
"web.telemetry-path", "/metrics",
"Path under which to expose metrics.",
)
queriesPath = flag.String(
"extend.query-path", "",
"Path to custom queries to run.",
)
onlyDumpMaps = flag.Bool(
"dumpmaps", false,
"Do not run, simply dump the maps.",
)
)
// Metric name parts.
const (
// Namespace for all metrics.
namespace = "pg"
// Subsystems.
exporter = "exporter"
// Metric label used for static string data thats handy to send to Prometheus
// e.g. version
staticLabelName = "static"
)
// landingPage contains the HTML served at '/'.
// TODO: Make this nicer and more informative.
var landingPage = []byte(`<html>
<head><title>Postgres exporter</title></head>
<body>
<h1>Postgres exporter</h1>
<p><a href='` + *metricPath + `'>Metrics</a></p>
</body>
</html>
`)
type ColumnUsage int
// Implements the yaml.Unmarshaller interface
func (this *ColumnUsage) UnmarshalYAML(unmarshal func(interface{}) error) error {
var value string
if err := unmarshal(&value); err != nil {
return err
}
columnUsage, err := stringToColumnUsage(value)
if err != nil {
return err
}
*this = columnUsage
return nil
}
const (
DISCARD ColumnUsage = iota // Ignore this column
LABEL ColumnUsage = iota // Use this column as a label
COUNTER ColumnUsage = iota // Use this column as a counter
GAUGE ColumnUsage = iota // Use this column as a gauge
MAPPEDMETRIC ColumnUsage = iota // Use this column with the supplied mapping of text values
DURATION ColumnUsage = iota // This column should be interpreted as a text duration (and converted to milliseconds)
)
// Special case matric mappings
const (
// Which metric mapping should be acquired using "SHOW" queries
SHOW_METRIC = "pg_runtime_variables"
)
// Regex used to get the "short-version" from the postgres version field.
var versionRegex = regexp.MustCompile(`^\w+ (\d+\.\d+\.\d+)`)
var lowestSupportedVersion = semver.MustParse("9.1.0")
// Parses the version of postgres into the short version string we can use to
// match behaviors.
func parseVersion(versionString string) (semver.Version, error) {
submatches := versionRegex.FindStringSubmatch(versionString)
if len(submatches) > 1 {
return semver.Make(submatches[1])
}
return semver.Version{},
errors.New(fmt.Sprintln("Could not find a postgres version in string:", versionString))
}
// User-friendly representation of a prometheus descriptor map
type ColumnMapping struct {
usage ColumnUsage `yaml:"usage"`
description string `yaml:"description"`
mapping map[string]float64 `yaml:"metric_mapping"` // Optional column mapping for MAPPEDMETRIC
supportedVersions semver.Range `yaml:"pg_version"` // Semantic version ranges which are supported. Unsupported columns are not queried (internally converted to DISCARD).
}
func (this *ColumnMapping) UnmarshalYAML(unmarshal func(interface{}) error) error {
type plain ColumnMapping
if err := unmarshal((*plain)(this)); err != nil {
return err
}
return nil
}
// Groups metric maps under a shared set of labels
type MetricMapNamespace struct {
labels []string // Label names for this namespace
columnMappings map[string]MetricMap // Column mappings in this namespace
}
// Stores the prometheus metric description which a given column will be mapped
// to by the collector
type MetricMap struct {
discard bool // Should metric be discarded during mapping?
vtype prometheus.ValueType // Prometheus valuetype
desc *prometheus.Desc // Prometheus descriptor
conversion func(interface{}) (float64, bool) // Conversion function to turn PG result into float64
}
// Metric descriptors for dynamically created metrics.
var variableMaps = map[string]map[string]ColumnMapping{
"pg_runtime_variable": map[string]ColumnMapping{
"max_connections": {GAUGE, "Sets the maximum number of concurrent connections.", nil, nil},
"max_files_per_process": {GAUGE, "Sets the maximum number of simultaneously open files for each server process.", nil, nil},
"max_function_args": {GAUGE, "Shows the maximum number of function arguments.", nil, nil},
"max_identifier_length": {GAUGE, "Shows the maximum identifier length.", nil, nil},
"max_index_keys": {GAUGE, "Shows the maximum number of index keys.", nil, nil},
"max_locks_per_transaction": {GAUGE, "Sets the maximum number of locks per transaction.", nil, nil},
"max_pred_locks_per_transaction": {GAUGE, "Sets the maximum number of predicate locks per transaction.", nil, nil},
"max_prepared_transactions": {GAUGE, "Sets the maximum number of simultaneously prepared transactions.", nil, nil},
//"max_stack_depth" : { GAUGE, "Sets the maximum number of concurrent connections.", nil }, // No dehumanize support yet
"max_standby_archive_delay": {DURATION, "Sets the maximum delay before canceling queries when a hot standby server is processing archived WAL data.", nil, nil},
"max_standby_streaming_delay": {DURATION, "Sets the maximum delay before canceling queries when a hot standby server is processing streamed WAL data.", nil, nil},
"max_wal_senders": {GAUGE, "Sets the maximum number of simultaneously running WAL sender processes.", nil, nil},
},
}
// TODO: revisit this with the semver system
func dumpMaps() {
for name, cmap := range metricMaps {
query, ok := queryOverrides[name]
if !ok {
fmt.Println(name)
} else {
for _, queryOverride := range query {
fmt.Println(name, queryOverride.versionRange, queryOverride.query)
}
}
for column, details := range cmap {
fmt.Printf(" %-40s %v\n", column, details)
}
fmt.Println()
}
}
var metricMaps = map[string]map[string]ColumnMapping{
"pg_stat_bgwriter": map[string]ColumnMapping{
"checkpoints_timed": {COUNTER, "Number of scheduled checkpoints that have been performed", nil, nil},
"checkpoints_req": {COUNTER, "Number of requested checkpoints that have been performed", nil, nil},
"checkpoint_write_time": {COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds", nil, nil},
"checkpoint_sync_time": {COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds", nil, nil},
"buffers_checkpoint": {COUNTER, "Number of buffers written during checkpoints", nil, nil},
"buffers_clean": {COUNTER, "Number of buffers written by the background writer", nil, nil},
"maxwritten_clean": {COUNTER, "Number of times the background writer stopped a cleaning scan because it had written too many buffers", nil, nil},
"buffers_backend": {COUNTER, "Number of buffers written directly by a backend", nil, nil},
"buffers_backend_fsync": {COUNTER, "Number of times a backend had to execute its own fsync call (normally the background writer handles those even when the backend does its own write)", nil, nil},
"buffers_alloc": {COUNTER, "Number of buffers allocated", nil, nil},
"stats_reset": {COUNTER, "Time at which these statistics were last reset", nil, nil},
},
"pg_stat_database": map[string]ColumnMapping{
"datid": {LABEL, "OID of a database", nil, nil},
"datname": {LABEL, "Name of this database", nil, nil},
"numbackends": {GAUGE, "Number of backends currently connected to this database. This is the only column in this view that returns a value reflecting current state; all other columns return the accumulated values since the last reset.", nil, nil},
"xact_commit": {COUNTER, "Number of transactions in this database that have been committed", nil, nil},
"xact_rollback": {COUNTER, "Number of transactions in this database that have been rolled back", nil, nil},
"blks_read": {COUNTER, "Number of disk blocks read in this database", nil, nil},
"blks_hit": {COUNTER, "Number of times disk blocks were found already in the buffer cache, so that a read was not necessary (this only includes hits in the PostgreSQL buffer cache, not the operating system's file system cache)", nil, nil},
"tup_returned": {COUNTER, "Number of rows returned by queries in this database", nil, nil},
"tup_fetched": {COUNTER, "Number of rows fetched by queries in this database", nil, nil},
"tup_inserted": {COUNTER, "Number of rows inserted by queries in this database", nil, nil},
"tup_updated": {COUNTER, "Number of rows updated by queries in this database", nil, nil},
"tup_deleted": {COUNTER, "Number of rows deleted by queries in this database", nil, nil},
"conflicts": {COUNTER, "Number of queries canceled due to conflicts with recovery in this database. (Conflicts occur only on standby servers; see pg_stat_database_conflicts for details.)", nil, nil},
"temp_files": {COUNTER, "Number of temporary files created by queries in this database. All temporary files are counted, regardless of why the temporary file was created (e.g., sorting or hashing), and regardless of the log_temp_files setting.", nil, nil},
"temp_bytes": {COUNTER, "Total amount of data written to temporary files by queries in this database. All temporary files are counted, regardless of why the temporary file was created, and regardless of the log_temp_files setting.", nil, nil},
"deadlocks": {COUNTER, "Number of deadlocks detected in this database", nil, nil},
"blk_read_time": {COUNTER, "Time spent reading data file blocks by backends in this database, in milliseconds", nil, nil},
"blk_write_time": {COUNTER, "Time spent writing data file blocks by backends in this database, in milliseconds", nil, nil},
"stats_reset": {COUNTER, "Time at which these statistics were last reset", nil, nil},
},
"pg_stat_database_conflicts": map[string]ColumnMapping{
"datid": {LABEL, "OID of a database", nil, nil},
"datname": {LABEL, "Name of this database", nil, nil},
"confl_tablespace": {COUNTER, "Number of queries in this database that have been canceled due to dropped tablespaces", nil, nil},
"confl_lock": {COUNTER, "Number of queries in this database that have been canceled due to lock timeouts", nil, nil},
"confl_snapshot": {COUNTER, "Number of queries in this database that have been canceled due to old snapshots", nil, nil},
"confl_bufferpin": {COUNTER, "Number of queries in this database that have been canceled due to pinned buffers", nil, nil},
"confl_deadlock": {COUNTER, "Number of queries in this database that have been canceled due to deadlocks", nil, nil},
},
"pg_locks": map[string]ColumnMapping{
"datname": {LABEL, "Name of this database", nil, nil},
"mode": {LABEL, "Type of Lock", nil, nil},
"count": {GAUGE, "Number of locks", nil, nil},
},
"pg_stat_replication": map[string]ColumnMapping{
"procpid": {DISCARD, "Process ID of a WAL sender process", nil, semver.MustParseRange("<9.2.0")},
"pid": {DISCARD, "Process ID of a WAL sender process", nil, semver.MustParseRange(">=9.2.0")},
"usesysid": {DISCARD, "OID of the user logged into this WAL sender process", nil, nil},
"usename": {DISCARD, "Name of the user logged into this WAL sender process", nil, nil},
"application_name": {DISCARD, "Name of the application that is connected to this WAL sender", nil, nil},
"client_addr": {LABEL, "IP address of the client connected to this WAL sender. If this field is null, it indicates that the client is connected via a Unix socket on the server machine.", nil, nil},
"client_hostname": {DISCARD, "Host name of the connected client, as reported by a reverse DNS lookup of client_addr. This field will only be non-null for IP connections, and only when log_hostname is enabled.", nil, nil},
"client_port": {DISCARD, "TCP port number that the client is using for communication with this WAL sender, or -1 if a Unix socket is used", nil, nil},
"backend_start": {DISCARD, "with time zone Time when this process was started, i.e., when the client connected to this WAL sender", nil, nil},
"backend_xmin": {DISCARD, "The current backend's xmin horizon.", nil, nil},
"state": {LABEL, "Current WAL sender state", nil, nil},
"sent_location": {DISCARD, "Last transaction log position sent on this connection", nil, nil},
"write_location": {DISCARD, "Last transaction log position written to disk by this standby server", nil, nil},
"flush_location": {DISCARD, "Last transaction log position flushed to disk by this standby server", nil, nil},
"replay_location": {DISCARD, "Last transaction log position replayed into the database on this standby server", nil, nil},
"sync_priority": {DISCARD, "Priority of this standby server for being chosen as the synchronous standby", nil, nil},
"sync_state": {DISCARD, "Synchronous state of this standby server", nil, nil},
"slot_name": {LABEL, "A unique, cluster-wide identifier for the replication slot", nil, semver.MustParseRange(">=9.2.0")},
"plugin": {DISCARD, "The base name of the shared object containing the output plugin this logical slot is using, or null for physical slots", nil, nil},
"slot_type": {DISCARD, "The slot type - physical or logical", nil, nil},
"datoid": {DISCARD, "The OID of the database this slot is associated with, or null. Only logical slots have an associated database", nil, nil},
"database": {DISCARD, "The name of the database this slot is associated with, or null. Only logical slots have an associated database", nil, nil},
"active": {DISCARD, "True if this slot is currently actively being used", nil, nil},
"active_pid": {DISCARD, "Process ID of a WAL sender process", nil, nil},
"xmin": {DISCARD, "The oldest transaction that this slot needs the database to retain. VACUUM cannot remove tuples deleted by any later transaction", nil, nil},
"catalog_xmin": {DISCARD, "The oldest transaction affecting the system catalogs that this slot needs the database to retain. VACUUM cannot remove catalog tuples deleted by any later transaction", nil, nil},
"restart_lsn": {DISCARD, "The address (LSN) of oldest WAL which still might be required by the consumer of this slot and thus won't be automatically removed during checkpoints", nil, nil},
"pg_current_xlog_location": {DISCARD, "pg_current_xlog_location", nil, nil},
"pg_xlog_location_diff": {GAUGE, "Lag in bytes between master and slave", nil, semver.MustParseRange(">=9.2.0")},
},
"pg_stat_activity": map[string]ColumnMapping{
"datname": {LABEL, "Name of this database", nil, nil},
"state": {LABEL, "connection state", nil, semver.MustParseRange(">=9.2.0")},
"count": {GAUGE, "number of connections in this state", nil, nil},
"max_tx_duration": {GAUGE, "max duration in seconds any active transaction has been running", nil, nil},
},
}
// Override querys are run in-place of simple namespace look ups, and provide
// advanced functionality. But they have a tendency to postgres version specific.
// There aren't too many versions, so we simply store customized versions using
// the semver matching we do for columns.
type OverrideQuery struct {
versionRange semver.Range
query string
}
// Overriding queries for namespaces above.
// TODO: validate this is a closed set in tests, and there are no overlaps
var queryOverrides = map[string][]OverrideQuery{
"pg_locks": []OverrideQuery{
{
semver.MustParseRange(">0.0.0"),
`SELECT pg_database.datname,tmp.mode,COALESCE(count,0) as count
FROM
(
VALUES ('accesssharelock'),
('rowsharelock'),
('rowexclusivelock'),
('shareupdateexclusivelock'),
('sharelock'),
('sharerowexclusivelock'),
('exclusivelock'),
('accessexclusivelock')
) AS tmp(mode) CROSS JOIN pg_database
LEFT JOIN
(SELECT database, lower(mode) AS mode,count(*) AS count
FROM pg_locks WHERE database IS NOT NULL
GROUP BY database, lower(mode)
) AS tmp2
ON tmp.mode=tmp2.mode and pg_database.oid = tmp2.database ORDER BY 1`,
},
},
"pg_stat_replication": []OverrideQuery{
{
semver.MustParseRange(">=9.2.0"),
`
SELECT *,
pg_current_xlog_location(),
pg_xlog_location_diff(pg_current_xlog_location(), replay_location)::float
FROM pg_stat_replication
`,
},
{
semver.MustParseRange("<9.2.0"),
`
SELECT *,
pg_current_xlog_location()
FROM pg_stat_replication
`,
},
},
"pg_stat_activity": []OverrideQuery{
// This query only works
{
semver.MustParseRange(">=9.2.0"),
`
SELECT
pg_database.datname,
tmp.state,
COALESCE(count,0) as count,
COALESCE(max_tx_duration,0) as max_tx_duration
FROM
(
VALUES ('active'),
('idle'),
('idle in transaction'),
('idle in transaction (aborted)'),
('fastpath function call'),
('disabled')
) AS tmp(state) CROSS JOIN pg_database
LEFT JOIN
(
SELECT
datname,
state,
count(*) AS count,
MAX(EXTRACT(EPOCH FROM now() - xact_start))::float AS max_tx_duration
FROM pg_stat_activity GROUP BY datname,state) AS tmp2
ON tmp.state = tmp2.state AND pg_database.datname = tmp2.datname
`,
},
// No query is applicable for 9.1 that gives any sensible data.
},
}
// Convert the query override file to the version-specific query override file
// for the exporter.
func makeQueryOverrideMap(pgVersion semver.Version, queryOverrides map[string][]OverrideQuery) map[string]string {
resultMap := make(map[string]string)
for name, overrideDef := range queryOverrides {
// Find a matching semver. We make it an error to have overlapping
// ranges at test-time, so only 1 should ever match.
matched := false
for _, queryDef := range overrideDef {
if queryDef.versionRange(pgVersion) {
resultMap[name] = queryDef.query
matched = true
break
}
}
if !matched {
log.Warnln("No query matched override for", name, "- disabling metric space.")
resultMap[name] = ""
}
}
return resultMap
}
// Add queries to the metricMaps and queryOverrides maps. Added queries do not
// respect version requirements, because it is assumed that the user knows
// what they are doing with their version of postgres.
//
// This function modifies metricMap and queryOverrideMap to contain the new
// queries.
// TODO: test code for all this.
// TODO: use proper struct type system
// TODO: the YAML this supports is "non-standard" - we should move away from it.
func addQueries(queriesPath string, pgVersion semver.Version, exporterMap map[string]MetricMapNamespace, queryOverrideMap map[string]string) error {
var extra map[string]interface{}
content, err := ioutil.ReadFile(queriesPath)
if err != nil {
return err
}
err = yaml.Unmarshal(content, &extra)
if err != nil {
return err
}
// Stores the loaded map representation
metricMaps := make(map[string]map[string]ColumnMapping)
newQueryOverrides := make(map[string]string)
for metric, specs := range extra {
log.Debugln("New user metric namespace from YAML:", metric)
for key, value := range specs.(map[interface{}]interface{}) {
switch key.(string) {
case "query":
query := value.(string)
newQueryOverrides[metric] = query
case "metrics":
for _, c := range value.([]interface{}) {
column := c.(map[interface{}]interface{})
for n, a := range column {
var columnMapping ColumnMapping
// Fetch the metric map we want to work on.
metricMap, ok := metricMaps[metric]
if !ok {
// Namespace for metric not found - add it.
metricMap = make(map[string]ColumnMapping)
metricMaps[metric] = metricMap
}
// Get name.
name := n.(string)
for attrKey, attrVal := range a.(map[interface{}]interface{}) {
switch attrKey.(string) {
case "usage":
usage, err := stringToColumnUsage(attrVal.(string))
if err != nil {
return err
}
columnMapping.usage = usage
case "description":
columnMapping.description = attrVal.(string)
}
}
// TODO: we should support this
columnMapping.mapping = nil
// Should we support this for users?
columnMapping.supportedVersions = nil
metricMap[name] = columnMapping
}
}
}
}
}
// Convert the loaded metric map into exporter representation
partialExporterMap := makeDescMap(pgVersion, metricMaps)
// Merge the two maps (which are now quite flatteend)
for k, v := range partialExporterMap {
_, found := exporterMap[k]
if found {
log.Debugln("Overriding metric", k, "from user YAML file.")
} else {
log.Debugln("Adding new metric", k, "from user YAML file.")
}
exporterMap[k] = v
}
// Merge the query override map
for k, v := range newQueryOverrides {
_, found := queryOverrideMap[k]
if found {
log.Debugln("Overriding query override", k, "from user YAML file.")
} else {
log.Debugln("Adding new query override", k, "from user YAML file.")
}
queryOverrideMap[k] = v
}
return nil
}
// Turn the MetricMap column mapping into a prometheus descriptor mapping.
func makeDescMap(pgVersion semver.Version, metricMaps map[string]map[string]ColumnMapping) map[string]MetricMapNamespace {
var metricMap = make(map[string]MetricMapNamespace)
for namespace, mappings := range metricMaps {
thisMap := make(map[string]MetricMap)
// Get the constant labels
var constLabels []string
for columnName, columnMapping := range mappings {
if columnMapping.usage == LABEL {
constLabels = append(constLabels, columnName)
}
}
for columnName, columnMapping := range mappings {
// Check column version compatibility for the current map
// Force to discard if not compatible.
if columnMapping.supportedVersions != nil {
if !columnMapping.supportedVersions(pgVersion) {
// It's very useful to be able to see what columns are being
// rejected.
log.Debugln(columnName, "is being forced to discard due to version incompatibility.")
thisMap[columnName] = MetricMap{
discard: true,
conversion: func(in interface{}) (float64, bool) {
return math.NaN(), true
},
}
continue
}
}
// Determine how to convert the column based on its usage.
switch columnMapping.usage {
case DISCARD, LABEL:
thisMap[columnName] = MetricMap{
discard: true,
conversion: func(in interface{}) (float64, bool) {
return math.NaN(), true
},
}
case COUNTER:
thisMap[columnName] = MetricMap{
vtype: prometheus.CounterValue,
desc: prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
conversion: func(in interface{}) (float64, bool) {
return dbToFloat64(in)
},
}
case GAUGE:
thisMap[columnName] = MetricMap{
vtype: prometheus.GaugeValue,
desc: prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
conversion: func(in interface{}) (float64, bool) {
return dbToFloat64(in)
},
}
case MAPPEDMETRIC:
thisMap[columnName] = MetricMap{
vtype: prometheus.GaugeValue,
desc: prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
conversion: func(in interface{}) (float64, bool) {
text, ok := in.(string)
if !ok {
return math.NaN(), false
}
val, ok := columnMapping.mapping[text]
if !ok {
return math.NaN(), false
}
return val, true
},
}
case DURATION:
thisMap[columnName] = MetricMap{
vtype: prometheus.GaugeValue,
desc: prometheus.NewDesc(fmt.Sprintf("%s_%s_milliseconds", namespace, columnName), columnMapping.description, constLabels, nil),
conversion: func(in interface{}) (float64, bool) {
var durationString string
switch t := in.(type) {
case []byte:
durationString = string(t)
case string:
durationString = t
default:
log.Errorln("DURATION conversion metric was not a string")
return math.NaN(), false
}
if durationString == "-1" {
return math.NaN(), false
}
d, err := time.ParseDuration(durationString)
if err != nil {
log.Errorln("Failed converting result to metric:", columnName, in, err)
return math.NaN(), false
}
return float64(d / time.Millisecond), true
},
}
}
}
metricMap[namespace] = MetricMapNamespace{constLabels, thisMap}
}
return metricMap
}
// convert a string to the corresponding ColumnUsage
func stringToColumnUsage(s string) (u ColumnUsage, err error) {
switch s {
case "DISCARD":
u = DISCARD
case "LABEL":
u = LABEL
case "COUNTER":
u = COUNTER
case "GAUGE":
u = GAUGE
case "MAPPEDMETRIC":
u = MAPPEDMETRIC
case "DURATION":
u = DURATION
default:
err = fmt.Errorf("wrong ColumnUsage given : %s", s)
}
return
}
// Convert database.sql types to float64s for Prometheus consumption. Null types are mapped to NaN. string and []byte
// types are mapped as NaN and !ok
func dbToFloat64(t interface{}) (float64, bool) {
switch v := t.(type) {
case int64:
return float64(v), true
case float64:
return v, true
case time.Time:
return float64(v.Unix()), true
case []byte:
// Try and convert to string and then parse to a float64
strV := string(v)
result, err := strconv.ParseFloat(strV, 64)
if err != nil {
return math.NaN(), false
}
return result, true
case string:
result, err := strconv.ParseFloat(v, 64)
if err != nil {
log.Infoln("Could not parse string:", err)
return math.NaN(), false
}
return result, true
case nil:
return math.NaN(), true
default:
return math.NaN(), false
}
}
// Convert database.sql to string for Prometheus labels. Null types are mapped to empty strings.
func dbToString(t interface{}) (string, bool) {
switch v := t.(type) {
case int64:
return fmt.Sprintf("%v", v), true
case float64:
return fmt.Sprintf("%v", v), true
case time.Time:
return fmt.Sprintf("%v", v.Unix()), true
case nil:
return "", true
case []byte:
// Try and convert to string
return string(v), true
case string:
return v, true
default:
return "", false
}
}
// Exporter collects Postgres metrics. It implements prometheus.Collector.
type Exporter struct {
dsn string
userQueriesPath string
duration, error prometheus.Gauge
totalScrapes prometheus.Counter
// Last version used to calculate metric map. If mismatch on scrape,
// then maps are recalculated.
lastMapVersion semver.Version
// Currently active variable map
variableMap map[string]MetricMapNamespace
// Currently active metric map
metricMap map[string]MetricMapNamespace
// Currently active query overrides
queryOverrides map[string]string
mappingMtx sync.RWMutex
}
// NewExporter returns a new PostgreSQL exporter for the provided DSN.
func NewExporter(dsn string, userQueriesPath string) *Exporter {
return &Exporter{
dsn: dsn,
userQueriesPath: userQueriesPath,
duration: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "last_scrape_duration_seconds",
Help: "Duration of the last scrape of metrics from PostgresSQL.",
}),
totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "scrapes_total",
Help: "Total number of times PostgresSQL was scraped for metrics.",
}),
error: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "last_scrape_error",
Help: "Whether the last scrape of metrics from PostgreSQL resulted in an error (1 for error, 0 for success).",
}),
variableMap: nil,
metricMap: nil,
queryOverrides: nil,
}
}
// Describe implements prometheus.Collector.
func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
// We cannot know in advance what metrics the exporter will generate
// from Postgres. So we use the poor man's describe method: Run a collect
// and send the descriptors of all the collected metrics. The problem
// here is that we need to connect to the Postgres DB. If it is currently
// unavailable, the descriptors will be incomplete. Since this is a
// stand-alone exporter and not used as a library within other code
// implementing additional metrics, the worst that can happen is that we
// don't detect inconsistent metrics created by this exporter
// itself. Also, a change in the monitored Postgres instance may change the
// exported metrics during the runtime of the exporter.
metricCh := make(chan prometheus.Metric)
doneCh := make(chan struct{})
go func() {
for m := range metricCh {
ch <- m.Desc()
}
close(doneCh)
}()
e.Collect(metricCh)
close(metricCh)
<-doneCh
}
// Collect implements prometheus.Collector.
func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
e.scrape(ch)
ch <- e.duration
ch <- e.totalScrapes
ch <- e.error
}
func newDesc(subsystem, name, help string) *prometheus.Desc {
return prometheus.NewDesc(
prometheus.BuildFQName(namespace, subsystem, name),
help, nil, nil,
)
}
// Query the SHOW variables from the query map
// TODO: make this more functional
func queryShowVariables(ch chan<- prometheus.Metric, db *sql.DB, variableMap map[string]MetricMapNamespace) []error {
log.Debugln("Querying SHOW variables")
nonFatalErrors := []error{}
for _, mapping := range variableMap {
for columnName, columnMapping := range mapping.columnMappings {
// Check for a discard request on this value
if columnMapping.discard {
continue
}
// Use SHOW to get the value
row := db.QueryRow(fmt.Sprintf("SHOW %s;", columnName))
var val interface{}
err := row.Scan(&val)
if err != nil {
nonFatalErrors = append(nonFatalErrors, errors.New(fmt.Sprintln("Error scanning runtime variable:", columnName, err)))
continue
}
fval, ok := columnMapping.conversion(val)
if !ok {
nonFatalErrors = append(nonFatalErrors, errors.New(fmt.Sprintln("Unexpected error parsing column: ", namespace, columnName, val)))
continue
}
ch <- prometheus.MustNewConstMetric(columnMapping.desc, columnMapping.vtype, fval)
}
}
return nonFatalErrors
}
// Query within a namespace mapping and emit metrics. Returns fatal errors if
// the scrape fails, and a slice of errors if they were non-fatal.
func queryNamespaceMapping(ch chan<- prometheus.Metric, db *sql.DB, namespace string, mapping MetricMapNamespace, queryOverrides map[string]string) ([]error, error) {
// Check for a query override for this namespace
query, found := queryOverrides[namespace]
if !found {
// No query override - do a simple * search.
query = fmt.Sprintf("SELECT * FROM %s;", namespace)
}
// Was this query disabled (i.e. nothing sensible can be queried on this
// version of PostgreSQL?
if query == "" {
// Return success (no pertinent data)
return []error{}, nil
}
// Don't fail on a bad scrape of one metric
rows, err := db.Query(query)
if err != nil {
return []error{}, errors.New(fmt.Sprintln("Error running query on database: ", namespace, err))
}
defer rows.Close()
var columnNames []string
columnNames, err = rows.Columns()
if err != nil {
return []error{}, errors.New(fmt.Sprintln("Error retrieving column list for: ", namespace, err))
}
// Make a lookup map for the column indices
var columnIdx = make(map[string]int, len(columnNames))
for i, n := range columnNames {
columnIdx[n] = i
}
var columnData = make([]interface{}, len(columnNames))
var scanArgs = make([]interface{}, len(columnNames))
for i := range columnData {
scanArgs[i] = &columnData[i]
}
nonfatalErrors := []error{}
for rows.Next() {
err = rows.Scan(scanArgs...)
if err != nil {
return []error{}, errors.New(fmt.Sprintln("Error retrieving rows:", namespace, err))
}
// Get the label values for this row
var labels = make([]string, len(mapping.labels))
for idx, columnName := range mapping.labels {
labels[idx], _ = dbToString(columnData[columnIdx[columnName]])
}
// Loop over column names, and match to scan data. Unknown columns
// will be filled with an untyped metric number *if* they can be
// converted to float64s. NULLs are allowed and treated as NaN.
for idx, columnName := range columnNames {
if metricMapping, ok := mapping.columnMappings[columnName]; ok {
// Is this a metricy metric?
if metricMapping.discard {
continue
}
value, ok := dbToFloat64(columnData[idx])
if !ok {
nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unexpected error parsing column: ", namespace, columnName, columnData[idx])))
continue
}
// Generate the metric
ch <- prometheus.MustNewConstMetric(metricMapping.desc, metricMapping.vtype, value, labels...)
} else {
// Unknown metric. Report as untyped if scan to float64 works, else note an error too.
desc := prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), fmt.Sprintf("Unknown metric from %s", namespace), nil, nil)
// Its not an error to fail here, since the values are
// unexpected anyway.
value, ok := dbToFloat64(columnData[idx])
if !ok {
nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unparseable column type - discarding: ", namespace, columnName, err)))
continue
}
log.Debugln(columnName, labels)
ch <- prometheus.MustNewConstMetric(desc, prometheus.UntypedValue, value, labels...)
}
}
}
return nonfatalErrors, nil
}
// Iterate through all the namespace mappings in the exporter and run their
// queries.
func queryNamespaceMappings(ch chan<- prometheus.Metric, db *sql.DB, metricMap map[string]MetricMapNamespace, queryOverrides map[string]string) map[string]error {
// Return a map of namespace -> errors
namespaceErrors := make(map[string]error)
for namespace, mapping := range metricMap {
log.Debugln("Querying namespace: ", namespace)
nonFatalErrors, err := queryNamespaceMapping(ch, db, namespace, mapping, queryOverrides)
// Serious error - a namespace disappeard
if err != nil {
namespaceErrors[namespace] = err
log.Infoln(err)
}
// Non-serious errors - likely version or parsing problems.
if len(nonFatalErrors) > 0 {
for _, err := range nonFatalErrors {
log.Infoln(err.Error())
}
}
}
return namespaceErrors
}
// Check and update the exporters query maps if the version has changed.
func (e *Exporter) checkMapVersions(ch chan<- prometheus.Metric, db *sql.DB) error {
log.Debugln("Querying Postgres Version")
versionRow := db.QueryRow("SELECT version();")
var versionString string
err := versionRow.Scan(&versionString)
if err != nil {
return errors.New(fmt.Sprintln("Error scanning version string:", err))
}
semanticVersion, err := parseVersion(versionString)
// Check if semantic version changed and recalculate maps if needed.
if semanticVersion.NE(e.lastMapVersion) || e.variableMap == nil || e.metricMap == nil {
log.Infoln("Semantic Version Changed:", e.lastMapVersion.String(), "->", semanticVersion.String())
e.mappingMtx.Lock()
e.variableMap = makeDescMap(semanticVersion, variableMaps)
e.metricMap = makeDescMap(semanticVersion, metricMaps)
e.queryOverrides = makeQueryOverrideMap(semanticVersion, queryOverrides)
e.lastMapVersion = semanticVersion
if e.userQueriesPath != "" {
if err := addQueries(e.userQueriesPath, semanticVersion, e.metricMap, e.queryOverrides); err != nil {
log.Errorln("Failed to reload user queries:", e.userQueriesPath, err)
}
}
e.mappingMtx.Unlock()
}
// Output the version as a special metric
versionDesc := prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, staticLabelName),
"Version string as reported by postgres", []string{"version", "short_version"}, nil)
ch <- prometheus.MustNewConstMetric(versionDesc,
prometheus.UntypedValue, 1, versionString, semanticVersion.String())
return nil
}
func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
defer func(begun time.Time) {
e.duration.Set(time.Since(begun).Seconds())
}(time.Now())
e.error.Set(0)
e.totalScrapes.Inc()
db, err := sql.Open("postgres", e.dsn)
if err != nil {
log.Infoln("Error opening connection to database:", err)
e.error.Set(1)
return
}
defer db.Close()
// Check if map versions need to be updated
if err := e.checkMapVersions(ch, db); err != nil {
log.Warnln("Postgres version could not be determined. Proceeding with outdated query maps.")
e.error.Set(1)
}
// Lock the exporter maps
e.mappingMtx.RLock()
defer e.mappingMtx.RUnlock()
// Handle querying the show variables
nonFatalErrors := queryShowVariables(ch, db, e.variableMap)
if len(nonFatalErrors) > 0 {
e.error.Set(1)
}
errMap := queryNamespaceMappings(ch, db, e.metricMap, e.queryOverrides)