Go-Expvar

Agent Check

Supported OS:

Go graph

Overview

Track the memory usage of your Go services and collect metrics instrumented from Go’s expvar package.

If you prefer to instrument your Go code using only dogstats-go, you can still use this integration to collect memory-related metrics.

Setup

Installation

The Go Expvar check is packaged with the Agent, so install the Agent anywhere you run Go services to collect metrics.

Configuration

Prepare your Go service

If your Go service doesn’t use the expvar package already, import it (import "expvar"). If you don’t want to instrument your own metrics with expvar - i.e. you only want to collect your service’s memory metrics - import the package using the blank identifier (import _ "expvar"). If your service doesn’t already listen for HTTP requests (with the http package), make it listen locally just for the Datadog Agent.

Host

Follow the instructions below to configure this check for an Agent running on a host. For containerized environments, see the Containerized section.

Connect the Agent

Edit the file go_expvar.d/conf.yaml, in the conf.d/ folder at the root of your Agent’s configuration directory. See the sample go_expvar.d/conf.yaml for all available configuration options.
Note: If you don’t configure a metrics list, the Agent still collects memstat metrics. Use metrics to tell the Agent which expvar vars to collect.
Restart the Agent.

Note: The Go Expvar integration can potentially emit custom metrics, which may impact your billing. By default, there is a limit of 350 metrics. If you require additional metrics, contact Datadog support.

Containerized

For containerized environments, see the Autodiscovery Integration Templates for guidance on applying the parameters below.

Parameter	Value
`<INTEGRATION_NAME>`	`go_expvar`
`<INIT_CONFIG>`	blank or `{}`
`<INSTANCE_CONFIG>`	`{"expvar_url": "http://%%host%%:8080"}`

Validation

Run the Agent’s status subcommand and look for go_expvar under the Checks section.

Data Collected

Metrics

go_expvar.memstats.alloc (gauge)	Bytes allocated and not yet freed Shown as byte
go_expvar.memstats.frees (gauge)	Number of frees Shown as operation
go_expvar.memstats.heap_alloc (gauge)	Bytes allocated and not yet freed Shown as byte
go_expvar.memstats.heap_idle (gauge)	Bytes in idle spans Shown as byte
go_expvar.memstats.heap_inuse (gauge)	Bytes in non-idle spans Shown as byte
go_expvar.memstats.heap_objects (gauge)	Total number of allocated objects Shown as item
go_expvar.memstats.heap_released (gauge)	Bytes released to the OS Shown as byte
go_expvar.memstats.heap_sys (gauge)	Bytes obtained from system Shown as byte
go_expvar.memstats.lookups (gauge)	Number of pointer lookups Shown as operation
go_expvar.memstats.mallocs (gauge)	Number of mallocs Shown as operation
go_expvar.memstats.num_gc (gauge)	Number of garbage collections Shown as garbage collection
go_expvar.memstats.pause_ns.95percentile (gauge)	95th percentile of recent GC pause durations Shown as nanosecond
go_expvar.memstats.pause_ns.avg (gauge)	Average of recent GC pause durations Shown as nanosecond
go_expvar.memstats.pause_ns.count (rate)	Number of submitted GC pause durations Shown as sample
go_expvar.memstats.pause_ns.max (gauge)	Max GC pause duration Shown as nanosecond
go_expvar.memstats.pause_ns.median (gauge)	Median GC pause duration Shown as nanosecond
go_expvar.memstats.pause_total_ns (gauge)	Total GC pause duration over lifetime of process Shown as nanosecond
go_expvar.memstats.total_alloc (gauge)	Bytes allocated (even if freed) Shown as byte
go_expvar.memstats.total_alloc.count (count)	Bytes allocated (even if freed) as monotonic count Shown as byte

Events

The Go-Expvar check does not include any events.

Service Checks

The Go-Expvar check does not include any service checks.

Troubleshooting

Need help? Contact Datadog support.

Datadog Docs