> ## Documentation Index
> Fetch the complete documentation index at: https://otel.fyi/llms.txt
> Use this file to discover all available pages before exploring further.

# Expvar

> OpenTelemetry receiver for Expvar

# Expvar Receiver

![Status](https://img.shields.io/badge/status-alpha-red)

**Available in:** `contrib`

**Maintainers:** [@jamesmoessis](https://github.com/jamesmoessis), [@MovieStoreGuy](https://github.com/MovieStoreGuy)

**Source:** [opentelemetry-collector-contrib](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/receiver/expvarreceiver)

## Supported Telemetry

![Metrics](https://img.shields.io/badge/metrics-alpha-green)

## Overview

## Configuration

### Default

By default, without any configuration, a request will be sent to `http://localhost:8000/debug/vars`
every 60 seconds. The default configuration is achieved by the following:

```yaml theme={null}
receivers:
  expvar:
```

### Customising

The following can be configured:

* Configure the HTTP client for scraping the expvar variables. The full set of
  configuration options for the client can be found in the core repo's
  [confighttp](https://github.com/open-telemetry/opentelemetry-collector/tree/main/config/confighttp#client-configuration).
  * defaults:
    * `endpoint = http://localhost:8000/debug/vars`
    * `timeout = 3s`
* `collection_interval` - Configure how often the metrics are scraped.
  * default: 1m
* `initial_delay` (default = `1s`): defines how long this receiver waits before starting.
* `metrics` - Enable or disable metrics by name.

### Example configuration

```yaml theme={null}
receivers:
  expvar:
    endpoint: "http://localhost:8000/custom/path"
    timeout: 1s
    collection_interval: 30s
    metrics:
      process.runtime.memstats.total_alloc:
        enabled: true
      process.runtime.memstats.mallocs:
        enabled: false
```

## Metrics

| Metric Name | Description | Unit | Type | Attributes |
| - | - | - | - | - |
| ✅ `process.runtime.memstats.buck_hash_sys` | Bytes of memory in profiling bucket hash tables. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.frees` | Cumulative count of heap objects freed. | \{objects} | Counter | |
| ✅ `process.runtime.memstats.gc_cpu_fraction` | The fraction of this program's available CPU time used by the GC since the program started. | 1 | Gauge | |
| ✅ `process.runtime.memstats.gc_sys` | Bytes of memory in garbage collection metadata. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_alloc` | Bytes of allocated heap objects. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_idle` | Bytes in idle (unused) spans. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_inuse` | Bytes in in-use spans. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_objects` | Number of allocated heap objects. | \{objects} | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_released` | Bytes of physical memory returned to the OS. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.heap_sys` | Bytes of heap memory obtained by the OS. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.last_pause` | The most recent stop-the-world pause time. | ns | Gauge | |
| ❌ `process.runtime.memstats.lookups` | Number of pointer lookups performed by the runtime. | \{lookups} | UpDownCounter | |
| ✅ `process.runtime.memstats.mallocs` | Cumulative count of heap objects allocated. | \{objects} | Counter | |
| ✅ `process.runtime.memstats.mcache_inuse` | Bytes of allocated mcache structures. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.mcache_sys` | Bytes of memory obtained from the OS for mcache structures. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.mspan_inuse` | Bytes of allocated mspan structures. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.mspan_sys` | Bytes of memory obtained from the OS for mspan structures. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.next_gc` | The target heap size of the next GC cycle. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.num_forced_gc` | Number of GC cycles that were forced by the application calling the GC function. | By | Counter | |
| ✅ `process.runtime.memstats.num_gc` | Number of completed GC cycles. | By | Counter | |
| ✅ `process.runtime.memstats.other_sys` | Bytes of memory in miscellaneous off-heap runtime allocations. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.pause_total` | The cumulative nanoseconds in GC stop-the-world pauses since the program started. | By | Counter | |
| ✅ `process.runtime.memstats.stack_inuse` | Bytes in stack spans. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.stack_sys` | Bytes of stack memory obtained from the OS. | By | UpDownCounter | |
| ✅ `process.runtime.memstats.sys` | Total bytes of memory obtained from the OS. | By | UpDownCounter | |
| ❌ `process.runtime.memstats.total_alloc` | Cumulative bytes allocated for heap objects. | By | Counter | |

## Configuration

### Example Configuration

```yaml theme={null}
# The default, minimal configuration
expvar/default:

# More custom configuration
expvar/custom:
  endpoint: "http://localhost:8000/custom/path"
  timeout: 5s
  collection_interval: 30s
  metrics:
    process.runtime.memstats.total_alloc:
      enabled: true
    process.runtime.memstats.mallocs:
      enabled: false

expvar/bad_hostless_endpoint:
  endpoint: "https:///this/aint/a/good/endpoint"

expvar/bad_invalid_url:
  endpoint: "#$%^&*()_"

expvar/bad_schemeless_endpoint:
  endpoint: "localhost:8000/custom/path"
```

***

*Last generated: 2026-10-05*