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github.com/moee/sql_exporter

Package sql_exporter

v0.0.0-...-bf4832d
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The latest major version is .

Published: Mar 4, 2020 | License: MIT | Module: github.com/moee/sql_exporter

Index

func OpenConnection

func OpenConnection(ctx context.Context, logContext, dsn string, maxConns, maxIdleConns int) (*sql.DB, error)

OpenConnection extracts the driver name from the DSN (expected as the URI scheme), adjusts it where necessary (e.g. some driver supported DSN formats don't include a scheme), opens a DB handle ensuring early termination if the context is closed (this is actually prevented by `database/sql` implementation), sets connection limits and returns the handle.

Below is the list of supported databases (with built in drivers) and their DSN formats. Unfortunately there is no dynamic way of loading a third party driver library (as e.g. with Java classpaths), so any driver additions require a binary rebuild.

MySQL

Using the https://github.com/go-sql-driver/mysql driver, DSN format (passed to the driver stripped of the `mysql://` prefix):

mysql://username:password@protocol(host:port)/dbname?param=value

PostgreSQL

Using the https://godoc.org/github.com/lib/pq driver, DSN format (passed through to the driver unchanged):

postgres://username:password@host:port/dbname?param=value

MS SQL Server

Using the https://github.com/denisenkom/go-mssqldb driver, DSN format (passed through to the driver unchanged):

sqlserver://username:password@host:port/instance?param=value

Clickhouse

Using the https://github.com/kshvakov/clickhouse driver, DSN format (passed to the driver with the`clickhouse://` prefix replaced with `tcp://`):

clickhouse://host:port?username=username&password=password&database=dbname&param=value

func PingDB

func PingDB(ctx context.Context, conn *sql.DB) error

PingDB is a wrapper around sql.DB.PingContext() that terminates as soon as the context is closed.

sql.DB does not actually pass along the context to the driver when opening a connection (which always happens if the database is down) and the driver uses an arbitrary timeout which may well be longer than ours. So we run the ping call in a goroutine and terminate immediately if the context is closed.

type Collector

type Collector interface {
	// Collect is the equivalent of prometheus.Collector.Collect() but takes a context to run in and a database to run on.
	Collect(context.Context, *sql.DB, chan<- Metric)
}

Collector is a self-contained group of SQL queries and metric families to collect from a specific database. It is conceptually similar to a prometheus.Collector.

func NewCollector

func NewCollector(logContext string, cc *config.CollectorConfig, constLabels []*dto.LabelPair) (Collector, errors.WithContext)

NewCollector returns a new Collector with the given configuration and database. The metrics it creates will all have the provided const labels applied.

type Exporter

type Exporter interface {
	prometheus.Gatherer

	// WithContext returns a (single use) copy of the Exporter, which will use the provided context for Gather() calls.
	WithContext(context.Context) Exporter
	// Config returns the Exporter's underlying Config object.
	Config() *config.Config
}

Exporter is a prometheus.Gatherer that gathers SQL metrics from targets and merges them with the default registry.

func NewExporter

func NewExporter(configFile string) (Exporter, error)

NewExporter returns a new Exporter with the provided config.

type Job

type Job interface {
	Targets() []Target
}

Job is a collection of targets with the same collectors applied.

func NewJob

func NewJob(jc *config.JobConfig, gc *config.GlobalConfig) (Job, errors.WithContext)

NewJob returns a new Job with the given configuration.

type Metric

type Metric interface {
	Desc() MetricDesc
	Write(out *dto.Metric) errors.WithContext
}

A Metric models a single sample value with its meta data being exported to Prometheus.

func NewInvalidMetric

func NewInvalidMetric(err errors.WithContext) Metric

NewInvalidMetric returns a metric whose Write method always returns the provided error.

func NewMetric

func NewMetric(desc MetricDesc, value float64, labelValues ...string) Metric

NewMetric returns a metric with one fixed value that cannot be changed.

NewMetric panics if the length of labelValues is not consistent with desc.labels().

type MetricDesc

type MetricDesc interface {
	Name() string
	Help() string
	ValueType() prometheus.ValueType
	ConstLabels() []*dto.LabelPair
	Labels() []string
	LogContext() string
}

MetricDesc is a descriptor for a family of metrics, sharing the same name, help, labes, type.

func NewAutomaticMetricDesc

func NewAutomaticMetricDesc(
	logContext, name, help string, valueType prometheus.ValueType, constLabels []*dto.LabelPair, labels ...string) MetricDesc

NewAutomaticMetricDesc creates a MetricDesc for automatically generated metrics.

type MetricFamily

type MetricFamily struct {
	// contains filtered or unexported fields
}

MetricFamily implements MetricDesc for SQL metrics, with logic for populating its labels and values from sql.Rows.

func NewMetricFamily

func NewMetricFamily(logContext string, mc *config.MetricConfig, constLabels []*dto.LabelPair) (*MetricFamily, errors.WithContext)

NewMetricFamily creates a new MetricFamily with the given metric config and const labels (e.g. job and instance).

func (MetricFamily) Collect

func (mf MetricFamily) Collect(row map[string]interface{}, ch chan<- Metric)

Collect is the equivalent of prometheus.Collector.Collect() but takes a Query output map to populate values from.

func (MetricFamily) ConstLabels

func (mf MetricFamily) ConstLabels() []*dto.LabelPair

ConstLabels implements MetricDesc.

func (MetricFamily) Help

func (mf MetricFamily) Help() string

Help implements MetricDesc.

func (MetricFamily) Labels

func (mf MetricFamily) Labels() []string

Labels implements MetricDesc.

func (MetricFamily) LogContext

func (mf MetricFamily) LogContext() string

LogContext implements MetricDesc.

func (MetricFamily) Name

func (mf MetricFamily) Name() string

Name implements MetricDesc.

func (MetricFamily) ValueType

func (mf MetricFamily) ValueType() prometheus.ValueType

ValueType implements MetricDesc.

type Query

type Query struct {
	// contains filtered or unexported fields
}

Query wraps a sql.Stmt and all the metrics populated from it. It helps extract keys and values from result rows.

func NewQuery

func NewQuery(logContext string, qc *config.QueryConfig, metricFamilies ...*MetricFamily) (*Query, errors.WithContext)

NewQuery returns a new Query that will populate the given metric families.

func (*Query) Collect

func (q *Query) Collect(ctx context.Context, conn *sql.DB, ch chan<- Metric)

Collect is the equivalent of prometheus.Collector.Collect() but takes a context to run in and a database to run on.

type Target

type Target interface {
	// Collect is the equivalent of prometheus.Collector.Collect(), but takes a context to run in.
	Collect(ctx context.Context, ch chan<- Metric)
}

Target collects SQL metrics from a single sql.DB instance. It aggregates one or more Collectors and it looks much like a prometheus.Collector, except its Collect() method takes a Context to run in.

func NewTarget

func NewTarget(
	logContext, name, dsn string, ccs []*config.CollectorConfig, constLabels prometheus.Labels, gc *config.GlobalConfig) (
	Target, errors.WithContext)

NewTarget returns a new Target with the given instance name, data source name, collectors and constant labels. An empty target name means the exporter is running in single target mode: no synthetic metrics will be exported.

Package Files

Documentation was rendered with GOOS=linux and GOARCH=amd64.

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