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collector.go
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collector.go
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package collector
import (
"bytes"
"context"
"crypto/sha256"
"database/sql"
"errors"
"fmt"
"hash"
"io"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/BurntSushi/toml"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
)
// Exporter collects Oracle DB metrics. It implements prometheus.Collector.
type Exporter struct {
config *Config
mu *sync.Mutex
metricsToScrape Metrics
scrapeInterval *time.Duration
dsn string
duration, error prometheus.Gauge
totalScrapes prometheus.Counter
scrapeErrors *prometheus.CounterVec
scrapeResults []prometheus.Metric
up prometheus.Gauge
db *sql.DB
logger log.Logger
}
// Config is the configuration of the exporter
type Config struct {
DSN string
MaxIdleConns int
MaxOpenConns int
CustomMetrics string
QueryTimeout int
DefaultMetricsFile string
}
// CreateDefaultConfig returns the default configuration of the Exporter
// it is to be of note that the DNS will be empty when
func CreateDefaultConfig() *Config {
return &Config{
MaxIdleConns: 0,
MaxOpenConns: 10,
CustomMetrics: "",
QueryTimeout: 5,
DefaultMetricsFile: "",
}
}
// Metric is an object description
type Metric struct {
Context string
Labels []string
MetricsDesc map[string]string
MetricsType map[string]string
MetricsBuckets map[string]map[string]string
FieldToAppend string
Request string
IgnoreZeroResult bool
}
// Metrics is a container structure for prometheus metrics
type Metrics struct {
Metric []Metric
}
var (
additionalMetrics Metrics
hashMap = make(map[int][]byte)
namespace = "oracledb"
exporterName = "exporter"
)
func maskDsn(dsn string) string {
parts := strings.Split(dsn, "@")
if len(parts) > 1 {
maskedURL := "***@" + parts[1]
return maskedURL
}
return dsn
}
// NewExporter creates a new Exporter instance
func NewExporter(logger log.Logger, cfg *Config) (*Exporter, error) {
e := &Exporter{
mu: &sync.Mutex{},
dsn: cfg.DSN,
duration: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporterName,
Name: "last_scrape_duration_seconds",
Help: "Duration of the last scrape of metrics from Oracle DB.",
}),
totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
Namespace: namespace,
Subsystem: exporterName,
Name: "scrapes_total",
Help: "Total number of times Oracle DB was scraped for metrics.",
}),
scrapeErrors: prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: namespace,
Subsystem: exporterName,
Name: "scrape_errors_total",
Help: "Total number of times an error occured scraping a Oracle database.",
}, []string{"collector"}),
error: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporterName,
Name: "last_scrape_error",
Help: "Whether the last scrape of metrics from Oracle DB resulted in an error (1 for error, 0 for success).",
}),
up: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Name: "up",
Help: "Whether the Oracle database server is up.",
}),
logger: logger,
config: cfg,
}
e.metricsToScrape = e.DefaultMetrics()
err := e.connect()
return e, err
}
// Describe describes all the metrics exported by the Oracle DB exporter.
func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
// We cannot know in advance what metrics the exporter will generate
// 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 Oracle 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 Oracle 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) {
// they are running scheduled scrapes we should only scrape new data
// on the interval
if e.scrapeInterval != nil && *e.scrapeInterval != 0 {
// read access must be checked
e.mu.Lock()
for _, r := range e.scrapeResults {
ch <- r
}
e.mu.Unlock()
return
}
// otherwise do a normal scrape per request
e.mu.Lock() // ensure no simultaneous scrapes
defer e.mu.Unlock()
e.scrape(ch)
ch <- e.duration
ch <- e.totalScrapes
ch <- e.error
e.scrapeErrors.Collect(ch)
ch <- e.up
}
// RunScheduledScrapes is only relevant for users of this package that want to set the scrape on a timer
// rather than letting it be per Collect call
func (e *Exporter) RunScheduledScrapes(ctx context.Context, si time.Duration) {
e.scrapeInterval = &si
ticker := time.NewTicker(si)
defer ticker.Stop()
for {
select {
case <-ticker.C:
e.mu.Lock() // ensure no simultaneous scrapes
e.scheduledScrape()
e.mu.Unlock()
case <-ctx.Done():
return
}
}
}
func (e *Exporter) scheduledScrape() {
metricCh := make(chan prometheus.Metric, 5)
wg := &sync.WaitGroup{}
wg.Add(1)
go func() {
defer wg.Done()
e.scrapeResults = []prometheus.Metric{}
for {
scrapeResult, more := <-metricCh
if more {
e.scrapeResults = append(e.scrapeResults, scrapeResult)
continue
}
return
}
}()
e.scrape(metricCh)
// report metadata metrics
metricCh <- e.duration
metricCh <- e.totalScrapes
metricCh <- e.error
e.scrapeErrors.Collect(metricCh)
metricCh <- e.up
close(metricCh)
wg.Wait()
}
func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
e.totalScrapes.Inc()
var err error
defer func(begun time.Time) {
e.duration.Set(time.Since(begun).Seconds())
if err == nil {
e.error.Set(0)
} else {
e.error.Set(1)
}
}(time.Now())
if err = e.db.Ping(); err != nil {
if strings.Contains(err.Error(), "sql: database is closed") {
level.Info(e.logger).Log("Reconnecting to DB")
err = e.connect()
if err != nil {
level.Error(e.logger).Log("Error reconnecting to DB", err)
}
}
}
if err = e.db.Ping(); err != nil {
level.Error(e.logger).Log("Error pinging oracle:", err)
e.up.Set(0)
return
}
level.Debug(e.logger).Log("Successfully pinged Oracle database: ", maskDsn(e.dsn))
e.up.Set(1)
if e.checkIfMetricsChanged() {
e.reloadMetrics()
}
wg := sync.WaitGroup{}
for _, metric := range e.metricsToScrape.Metric {
wg.Add(1)
metric := metric //https://golang.org/doc/faq#closures_and_goroutines
go func() {
defer wg.Done()
level.Debug(e.logger).Log("About to scrape metric: ")
level.Debug(e.logger).Log("- Metric MetricsDesc: ", metric.MetricsDesc)
level.Debug(e.logger).Log("- Metric Context: ", metric.Context)
level.Debug(e.logger).Log("- Metric MetricsType: ", metric.MetricsType)
level.Debug(e.logger).Log("- Metric MetricsBuckets: ", metric.MetricsBuckets, "(Ignored unless Histogram type)")
level.Debug(e.logger).Log("- Metric Labels: ", metric.Labels)
level.Debug(e.logger).Log("- Metric FieldToAppend: ", metric.FieldToAppend)
level.Debug(e.logger).Log("- Metric IgnoreZeroResult: ", metric.IgnoreZeroResult)
level.Debug(e.logger).Log("- Metric Request: ", metric.Request)
if len(metric.Request) == 0 {
level.Error(e.logger).Log("Error scraping for ", metric.MetricsDesc, ". Did you forget to define request in your toml file?")
return
}
if len(metric.MetricsDesc) == 0 {
level.Error(e.logger).Log("Error scraping for query", metric.Request, ". Did you forget to define metricsdesc in your toml file?")
return
}
for column, metricType := range metric.MetricsType {
if metricType == "histogram" {
_, ok := metric.MetricsBuckets[column]
if !ok {
level.Error(e.logger).Log("Unable to find MetricsBuckets configuration key for metric. (metric=" + column + ")")
return
}
}
}
scrapeStart := time.Now()
if err = e.ScrapeMetric(e.db, ch, metric); err != nil {
level.Error(e.logger).Log("Error scraping for", metric.Context, "_", metric.MetricsDesc, time.Since(scrapeStart), ":", err)
e.scrapeErrors.WithLabelValues(metric.Context).Inc()
} else {
level.Debug(e.logger).Log("Successfully scraped metric: ", metric.Context, metric.MetricsDesc, time.Since(scrapeStart))
}
}()
}
wg.Wait()
}
func (e *Exporter) connect() error {
level.Debug(e.logger).Log("Launching connection: ", maskDsn(e.dsn))
db, err := sql.Open("oracle", e.dsn)
if err != nil {
level.Error(e.logger).Log("Error while connecting to", e.dsn)
return err
}
level.Debug(e.logger).Log("set max idle connections to ", e.config.MaxIdleConns)
db.SetMaxIdleConns(e.config.MaxIdleConns)
level.Debug(e.logger).Log("set max open connections to ", e.config.MaxOpenConns)
db.SetMaxOpenConns(e.config.MaxOpenConns)
level.Debug(e.logger).Log("Successfully connected to: ", maskDsn(e.dsn))
e.db = db
return nil
}
func (e *Exporter) checkIfMetricsChanged() bool {
for i, _customMetrics := range strings.Split(e.config.CustomMetrics, ",") {
if len(_customMetrics) == 0 {
continue
}
level.Debug(e.logger).Log("Checking modifications in following metrics definition file:", _customMetrics)
h := sha256.New()
if err := hashFile(h, _customMetrics); err != nil {
level.Error(e.logger).Log("Unable to get file hash", err)
return false
}
// If any of files has been changed reload metrics
if !bytes.Equal(hashMap[i], h.Sum(nil)) {
level.Info(e.logger).Log(_customMetrics, "has been changed. Reloading metrics...")
hashMap[i] = h.Sum(nil)
return true
}
}
return false
}
func hashFile(h hash.Hash, fn string) error {
f, err := os.Open(fn)
if err != nil {
return err
}
defer f.Close()
if _, err := io.Copy(h, f); err != nil {
return err
}
return nil
}
func (e *Exporter) reloadMetrics() {
// Truncate metricsToScrape
e.metricsToScrape.Metric = []Metric{}
// Load default metrics
defaultMetrics := e.DefaultMetrics()
e.metricsToScrape.Metric = defaultMetrics.Metric
// If custom metrics, load it
if strings.Compare(e.config.CustomMetrics, "") != 0 {
for _, _customMetrics := range strings.Split(e.config.CustomMetrics, ",") {
if _, err := toml.DecodeFile(_customMetrics, &additionalMetrics); err != nil {
level.Error(e.logger).Log(err)
panic(errors.New("Error while loading " + _customMetrics))
} else {
level.Info(e.logger).Log("Successfully loaded custom metrics from: " + _customMetrics)
}
e.metricsToScrape.Metric = append(e.metricsToScrape.Metric, additionalMetrics.Metric...)
}
} else {
level.Debug(e.logger).Log("No custom metrics defined.")
}
}
// ScrapeMetric is an interface method to call scrapeGenericValues using Metric struct values
func (e *Exporter) ScrapeMetric(db *sql.DB, ch chan<- prometheus.Metric, metricDefinition Metric) error {
level.Debug(e.logger).Log("Calling function ScrapeGenericValues()")
return e.scrapeGenericValues(db, ch, metricDefinition.Context, metricDefinition.Labels,
metricDefinition.MetricsDesc, metricDefinition.MetricsType, metricDefinition.MetricsBuckets,
metricDefinition.FieldToAppend, metricDefinition.IgnoreZeroResult,
metricDefinition.Request)
}
// generic method for retrieving metrics.
func (e *Exporter) scrapeGenericValues(db *sql.DB, ch chan<- prometheus.Metric, context string, labels []string,
metricsDesc map[string]string, metricsType map[string]string, metricsBuckets map[string]map[string]string, fieldToAppend string, ignoreZeroResult bool, request string) error {
metricsCount := 0
genericParser := func(row map[string]string) error {
// Construct labels value
labelsValues := []string{}
for _, label := range labels {
labelsValues = append(labelsValues, row[label])
}
// Construct Prometheus values to sent back
for metric, metricHelp := range metricsDesc {
value, err := strconv.ParseFloat(strings.TrimSpace(row[metric]), 64)
// If not a float, skip current metric
if err != nil {
level.Error(e.logger).Log("Unable to convert current value to float (metric=" + metric +
",metricHelp=" + metricHelp + ",value=<" + row[metric] + ">)")
continue
}
level.Debug(e.logger).Log("Query result looks like: ", value)
// If metric do not use a field content in metric's name
if strings.Compare(fieldToAppend, "") == 0 {
desc := prometheus.NewDesc(
prometheus.BuildFQName(namespace, context, metric),
metricHelp,
labels, nil,
)
if metricsType[strings.ToLower(metric)] == "histogram" {
count, err := strconv.ParseUint(strings.TrimSpace(row["count"]), 10, 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert count value to int (metric=" + metric +
",metricHelp=" + metricHelp + ",value=<" + row["count"] + ">)")
continue
}
buckets := make(map[float64]uint64)
for field, le := range metricsBuckets[metric] {
lelimit, err := strconv.ParseFloat(strings.TrimSpace(le), 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert bucket limit value to float (metric=" + metric +
",metricHelp=" + metricHelp + ",bucketlimit=<" + le + ">)")
continue
}
counter, err := strconv.ParseUint(strings.TrimSpace(row[field]), 10, 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert ", field, " value to int (metric="+metric+
",metricHelp="+metricHelp+",value=<"+row[field]+">)")
continue
}
buckets[lelimit] = counter
}
ch <- prometheus.MustNewConstHistogram(desc, count, value, buckets, labelsValues...)
} else {
ch <- prometheus.MustNewConstMetric(desc, getMetricType(metric, metricsType), value, labelsValues...)
}
// If no labels, use metric name
} else {
desc := prometheus.NewDesc(
prometheus.BuildFQName(namespace, context, cleanName(row[fieldToAppend])),
metricHelp,
nil, nil,
)
if metricsType[strings.ToLower(metric)] == "histogram" {
count, err := strconv.ParseUint(strings.TrimSpace(row["count"]), 10, 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert count value to int (metric=" + metric +
",metricHelp=" + metricHelp + ",value=<" + row["count"] + ">)")
continue
}
buckets := make(map[float64]uint64)
for field, le := range metricsBuckets[metric] {
lelimit, err := strconv.ParseFloat(strings.TrimSpace(le), 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert bucket limit value to float (metric=" + metric +
",metricHelp=" + metricHelp + ",bucketlimit=<" + le + ">)")
continue
}
counter, err := strconv.ParseUint(strings.TrimSpace(row[field]), 10, 64)
if err != nil {
level.Error(e.logger).Log("Unable to convert ", field, " value to int (metric="+metric+
",metricHelp="+metricHelp+",value=<"+row[field]+">)")
continue
}
buckets[lelimit] = counter
}
ch <- prometheus.MustNewConstHistogram(desc, count, value, buckets)
} else {
ch <- prometheus.MustNewConstMetric(desc, getMetricType(metric, metricsType), value)
}
}
metricsCount++
}
return nil
}
level.Debug(e.logger).Log("Calling function GeneratePrometheusMetrics()")
err := e.generatePrometheusMetrics(db, genericParser, request)
level.Debug(e.logger).Log("ScrapeGenericValues() - metricsCount: ", metricsCount)
if err != nil {
return err
}
if !ignoreZeroResult && metricsCount == 0 {
return errors.New("No metrics found while parsing")
}
return err
}
// inspired by https://kylewbanks.com/blog/query-result-to-map-in-golang
// Parse SQL result and call parsing function to each row
func (e *Exporter) generatePrometheusMetrics(db *sql.DB, parse func(row map[string]string) error, query string) error {
ctx, cancel := context.WithTimeout(context.Background(), time.Duration(e.config.QueryTimeout)*time.Second)
defer cancel()
rows, err := db.QueryContext(ctx, query)
if ctx.Err() == context.DeadlineExceeded {
return errors.New("Oracle query timed out")
}
if err != nil {
return err
}
cols, err := rows.Columns()
defer rows.Close()
for rows.Next() {
// Create a slice of interface{}'s to represent each column,
// and a second slice to contain pointers to each item in the columns slice.
columns := make([]interface{}, len(cols))
columnPointers := make([]interface{}, len(cols))
for i := range columns {
columnPointers[i] = &columns[i]
}
// Scan the result into the column pointers...
if err := rows.Scan(columnPointers...); err != nil {
return err
}
// Create our map, and retrieve the value for each column from the pointers slice,
// storing it in the map with the name of the column as the key.
m := make(map[string]string)
for i, colName := range cols {
val := columnPointers[i].(*interface{})
m[strings.ToLower(colName)] = fmt.Sprintf("%v", *val)
}
// Call function to parse row
if err := parse(m); err != nil {
return err
}
}
return nil
}
func getMetricType(metricType string, metricsType map[string]string) prometheus.ValueType {
var strToPromType = map[string]prometheus.ValueType{
"gauge": prometheus.GaugeValue,
"counter": prometheus.CounterValue,
"histogram": prometheus.UntypedValue,
}
strType, ok := metricsType[strings.ToLower(metricType)]
if !ok {
return prometheus.GaugeValue
}
valueType, ok := strToPromType[strings.ToLower(strType)]
if !ok {
panic(errors.New("Error while getting prometheus type " + strings.ToLower(strType)))
}
return valueType
}
func cleanName(s string) string {
s = strings.Replace(s, " ", "_", -1) // Remove spaces
s = strings.Replace(s, "(", "", -1) // Remove open parenthesis
s = strings.Replace(s, ")", "", -1) // Remove close parenthesis
s = strings.Replace(s, "/", "", -1) // Remove forward slashes
s = strings.Replace(s, "*", "", -1) // Remove asterisks
s = strings.ToLower(s)
return s
}
func (e *Exporter) logError(s string) {
_ = level.Error(e.logger).Log(s)
}
func (e *Exporter) logDebug(s string) {
_ = level.Debug(e.logger).Log(s)
}