forked from prometheus-community/postgres_exporter
/
postgres_exporter.go
1018 lines (905 loc) · 36.2 KB
/
postgres_exporter.go
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package main
import (
"database/sql"
"errors"
"flag"
"fmt"
"io/ioutil"
"math"
"net/http"
"net/url"
"os"
"regexp"
"runtime"
"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"
)
// Version is set during build to the git describe version
// (semantic version)-(commitish) form.
var Version = "0.0.1"
var sharedDBConn *sql.DB
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.",
)
showVersion = flag.Bool("version", false, "print version and exit")
)
// 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 cu 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>
`)
// ColumnUsage should be one of several enum values which describe how a
// queried row is to be converted to a Prometheus metric.
type ColumnUsage int
// nolint: golint
const (
DISCARD ColumnUsage = iota // Ignore cu column
LABEL ColumnUsage = iota // Use cu column as a label
COUNTER ColumnUsage = iota // Use cu column as a counter
GAUGE ColumnUsage = iota // Use cu column as a gauge
MAPPEDMETRIC ColumnUsage = iota // Use cu column with the supplied mapping of text values
DURATION ColumnUsage = iota // This column should be interpreted as a text duration (and converted to milliseconds)
)
// UnmarshalYAML implements the yaml.Unmarshaller interface.
func (cu *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
}
*cu = columnUsage
return nil
}
// 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))
}
// ColumnMapping is the 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).
}
// UnmarshalYAML implements yaml.Unmarshaller
func (cm *ColumnMapping) UnmarshalYAML(unmarshal func(interface{}) error) error {
type plain ColumnMapping
return unmarshal((*plain)(cm))
}
// MetricMapNamespace groups metric maps under a shared set of labels.
type MetricMapNamespace struct {
labels []string // Label names for cu namespace
columnMappings map[string]MetricMap // Column mappings in cu namespace
}
// MetricMap 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
}
// TODO: revisit cu with the semver system
func dumpMaps() {
for name, cmap := range builtinMetricMaps {
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 builtinMetricMaps = map[string]map[string]ColumnMapping{
"pg_stat_bgwriter": {
"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": {
"datid": {LABEL, "OID of a database", nil, nil},
"datname": {LABEL, "Name of cu database", nil, nil},
"numbackends": {GAUGE, "Number of backends currently connected to cu database. This is the only column in cu 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 cu database that have been committed", nil, nil},
"xact_rollback": {COUNTER, "Number of transactions in cu database that have been rolled back", nil, nil},
"blks_read": {COUNTER, "Number of disk blocks read in cu 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 (cu 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 cu database", nil, nil},
"tup_fetched": {COUNTER, "Number of rows fetched by queries in cu database", nil, nil},
"tup_inserted": {COUNTER, "Number of rows inserted by queries in cu database", nil, nil},
"tup_updated": {COUNTER, "Number of rows updated by queries in cu database", nil, nil},
"tup_deleted": {COUNTER, "Number of rows deleted by queries in cu database", nil, nil},
"conflicts": {COUNTER, "Number of queries canceled due to conflicts with recovery in cu 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 cu 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 cu 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 cu database", nil, nil},
"blk_read_time": {COUNTER, "Time spent reading data file blocks by backends in cu database, in milliseconds", nil, nil},
"blk_write_time": {COUNTER, "Time spent writing data file blocks by backends in cu database, in milliseconds", nil, nil},
"stats_reset": {COUNTER, "Time at which these statistics were last reset", nil, nil},
},
"pg_stat_database_conflicts": {
"datid": {LABEL, "OID of a database", nil, nil},
"datname": {LABEL, "Name of cu database", nil, nil},
"confl_tablespace": {COUNTER, "Number of queries in cu database that have been canceled due to dropped tablespaces", nil, nil},
"confl_lock": {COUNTER, "Number of queries in cu database that have been canceled due to lock timeouts", nil, nil},
"confl_snapshot": {COUNTER, "Number of queries in cu database that have been canceled due to old snapshots", nil, nil},
"confl_bufferpin": {COUNTER, "Number of queries in cu database that have been canceled due to pinned buffers", nil, nil},
"confl_deadlock": {COUNTER, "Number of queries in cu database that have been canceled due to deadlocks", nil, nil},
},
"pg_locks": {
"datname": {LABEL, "Name of cu database", nil, nil},
"mode": {LABEL, "Type of Lock", nil, nil},
"count": {GAUGE, "Number of locks", nil, nil},
},
"pg_stat_replication": {
"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 cu WAL sender process", nil, nil},
"usename": {DISCARD, "Name of the user logged into cu WAL sender process", nil, nil},
"application_name": {DISCARD, "Name of the application that is connected to cu WAL sender", nil, nil},
"client_addr": {LABEL, "IP address of the client connected to cu WAL sender. If cu 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 cu WAL sender, or -1 if a Unix socket is used", nil, nil},
"backend_start": {DISCARD, "with time zone Time when cu process was started, i.e., when the client connected to cu 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 cu connection", nil, nil},
"write_location": {DISCARD, "Last transaction log position written to disk by cu standby server", nil, nil},
"flush_location": {DISCARD, "Last transaction log position flushed to disk by cu standby server", nil, nil},
"replay_location": {DISCARD, "Last transaction log position replayed into the database on cu standby server", nil, nil},
"sync_priority": {DISCARD, "Priority of cu standby server for being chosen as the synchronous standby", nil, nil},
"sync_state": {DISCARD, "Synchronous state of cu 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 cu 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 cu slot is associated with, or null. Only logical slots have an associated database", nil, nil},
"database": {DISCARD, "The name of the database cu slot is associated with, or null. Only logical slots have an associated database", nil, nil},
"active": {DISCARD, "True if cu 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 cu 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 cu 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 cu 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")},
"confirmed_flush_lsn": {DISCARD, "LSN position a consumer of a slot has confirmed flushing the data received", nil, nil},
},
"pg_stat_activity": {
"datname": {LABEL, "Name of cu database", nil, nil},
"state": {LABEL, "connection state", nil, semver.MustParseRange(">=9.2.0")},
"count": {GAUGE, "number of connections in cu state", nil, nil},
"max_tx_duration": {GAUGE, "max duration in seconds any active transaction has been running", nil, nil},
},
}
// OverrideQuery 's 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 cu is a closed set in tests, and there are no overlaps
var queryOverrides = map[string][]OverrideQuery{
"pg_locks": {
{
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": {
{
semver.MustParseRange(">=9.2.0"),
`
SELECT *,
(case pg_is_in_recovery() when 't' then null else pg_current_xlog_location() end) AS pg_current_xlog_location,
(case pg_is_in_recovery() when 't' then null else pg_xlog_location_diff(pg_current_xlog_location(), replay_location)::float end) AS pg_xlog_location_diff
FROM pg_stat_replication
`,
},
{
semver.MustParseRange("<9.2.0"),
`
SELECT *,
(case pg_is_in_recovery() when 't' then null else pg_current_xlog_location() end) AS pg_current_xlog_location
FROM pg_stat_replication
`,
},
},
"pg_stat_activity": {
// 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 builtinMetricMaps 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 cu.
// TODO: use proper struct type system
// TODO: the YAML cu 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 cu
columnMapping.mapping = nil
// Should we support cu 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 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).",
}),
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 cu 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 cu 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 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 cu namespace
query, found := queryOverrides[namespace]
// Was cu query disabled (i.e. nothing sensible can be queried on cu
// version of PostgreSQL?
if query == "" && found {
// Return success (no pertinent data)
return []error{}, nil
}
// Don't fail on a bad scrape of one metric
var rows *sql.Rows
var err error
if !found {
// I've no idea how to avoid this properly at the moment, but this is
// an admin tool so you're not injecting SQL right?
// nolint: gas
rows, err = db.Query(fmt.Sprintf("SELECT * FROM %s;", namespace))
} else {
rows, err = db.Query(query)
}
if err != nil {
return []error{}, errors.New(fmt.Sprintln("Error running query on database: ", namespace, err))
}
defer rows.Close() // nolint: errcheck
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 cu 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 cu 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 fmt.Errorf("Error scanning version string: %v", err)
}
semanticVersion, err := parseVersion(versionString)
if err != nil {
return fmt.Errorf("Error parsing version string: %v", err)
}
if semanticVersion.LT(lowestSupportedVersion) {
log.Warnln("PostgreSQL version is lower then our lowest supported version! Got", semanticVersion.String(), "minimum supported is", lowestSupportedVersion.String())
}
// Check if semantic version changed and recalculate maps if needed.
if semanticVersion.NE(e.lastMapVersion) || e.metricMap == nil {
log.Infoln("Semantic Version Changed:", e.lastMapVersion.String(), "->", semanticVersion.String())
e.mappingMtx.Lock()
e.metricMap = makeDescMap(semanticVersion, builtinMetricMaps)
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 getDB(conn string) (*sql.DB, error) {
if sharedDBConn == nil {
d, err := sql.Open("postgres", conn)
if err != nil {
return nil, err
}
err = d.Ping()
if err != nil {
return nil, err
}
d.SetMaxOpenConns(1)
d.SetMaxIdleConns(1)
sharedDBConn = d
}
return sharedDBConn, 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 := getDB(e.dsn)
if err != nil {
loggableDsn := "could not parse DATA_SOURCE_NAME"
if pDsn, pErr := url.Parse(e.dsn); pErr != nil {
pDsn.User = url.UserPassword(pDsn.User.Username(), "xxx")
loggableDsn = pDsn.String()
}
log.Infof("Error opening connection to database (%s): %s", loggableDsn, err)
e.error.Set(1)
return
}
// Check if map versions need to be updated
if err := e.checkMapVersions(ch, db); err != nil {
log.Warnln("Proceeding with outdated query maps, as the Postgres version could not be determined:", err)
e.error.Set(1)
}
// Lock the exporter maps
e.mappingMtx.RLock()
defer e.mappingMtx.RUnlock()
if err := querySettings(ch, db); err != nil {
log.Infof("Error retrieving settings: %s", err)
e.error.Set(1)
}
errMap := queryNamespaceMappings(ch, db, e.metricMap, e.queryOverrides)
if len(errMap) > 0 {
e.error.Set(1)
}
}
func main() {
flag.Parse()
if *showVersion {
fmt.Printf(
"postgres_exporter %s (built with %s)\n",
Version, runtime.Version(),
)
return
}
if *onlyDumpMaps {
dumpMaps()
return
}
dsn := os.Getenv("DATA_SOURCE_NAME")