# Internal telemetry
You can inspect the health of any OpenTelemetry Collector instance by checking
its own internal telemetry. Read on to learn about this telemetry and how to
configure it to help you
[monitor](#use-internal-telemetry-to-monitor-the-collector) and
[troubleshoot](/docs/collector/troubleshooting/) the Collector.
> [!WARNING]
>
> The Collector uses the OpenTelemetry SDK
> [declarative configuration schema](https://github.com/open-telemetry/opentelemetry-configuration)
> for configuring how to export its internal telemetry. This schema is still
> under [development](/docs/specs/otel/document-status/) and may undergo
> **breaking changes** in future releases. We intend to keep supporting older
> schemas until a 1.0 schema release is available, and offer a transition period
> for users to update their configurations before dropping pre-1.0 schemas. For
> details and to track progress see
> [issue #10808](https://github.com/open-telemetry/opentelemetry-collector/issues/10808).
## Activate internal telemetry in the Collector
By default, the Collector exposes its own telemetry in two ways:
- Internal [metrics](#configure-internal-metrics) are exposed using a Prometheus
interface which defaults to port `8888`.
- [Logs](#configure-internal-logs) are emitted to `stderr` by default.
### Configure resource attributes
The Collector's automatically attaches the `service.name`, `service.version`,
and `service.instance.id` (randomly generated) resource attributes to its
internal telemetry signals. These can be disabled by setting the attribute value
to `null` (ex. `service.name: null`).
If you'd like to add additional resource attributes to the Collector's internal
telemetry signals (traces, metrics, and logs) you can set them under
`service::telemetry::resource`:
```yaml
service:
telemetry:
resource:
attribute_key: 'attribute_value'
```
### Configure internal metrics
#### OTLP exporter for internal metrics
You can configure how internal metrics are generated and exposed by the
Collector. By default, the Collector generates basic metrics about itself and
exposes them using the OpenTelemetry Go
[Prometheus exporter](https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/prometheus)
for scraping at `http://127.0.0.1:8888/metrics`.
The Collector can push its internal metrics to an OTLP backend via the following
configuration:
```yaml
service:
telemetry:
metrics:
readers:
- periodic:
exporter:
otlp:
protocol: http/protobuf
endpoint: https://backend:4318
```
#### Prometheus endpoint for internal metrics
Alternatively, you can expose the Prometheus endpoint to one specific or all
network interfaces when needed. For containerized environments, you might want
to expose this port on a public interface.
Set the Prometheus config under `service::telemetry::metrics`:
```yaml
service:
telemetry:
metrics:
readers:
- pull:
exporter:
prometheus:
host: '0.0.0.0'
port: 8888
```
If you want to add additional labels to the Prometheus metrics, you can add them
with `prometheus::with_resource_constant_labels`:
```yaml
prometheus:
host: '0.0.0.0'
port: 8888
with_resource_constant_labels:
included:
- label_key
```
And then reference the labels in `service::telemetry::resource`:
```yaml
resource:
label_key: label_value
```
#### Service address
> [!NOTE] Internal telemetry configuration changes
>
> As of Collector [v0.123.0][], the `service::telemetry::metrics::address`
> setting is ignored. In earlier versions, it could be configured with:
>
> ```yaml
> service:
> telemetry:
> metrics:
> address: 0.0.0.0:8888
> ```
[v0.123.0]:
https://github.com/open-telemetry/opentelemetry-collector/releases/tag/v0.123.0
#### Metric verbosity
You can adjust the verbosity of the Collector metrics output by setting the
`level` field to one of the following values:
- `none`: no telemetry is collected.
- `basic`: essential service telemetry.
- `normal`: the default level, adds standard indicators on top of basic.
- `detailed`: the most verbose level, includes dimensions and views.
Each verbosity level represents a threshold at which certain metrics are
emitted. For the complete list of metrics, with a breakdown by level, see
[Lists of internal metrics](#lists-of-internal-metrics).
The default level for metrics output is `normal`. To use another level, set
`service::telemetry::metrics::level`:
```yaml
service:
telemetry:
metrics:
level: detailed
```
#### Metric views
You can further configure how metrics from the Collector are emitted by using
[`views`](/docs/specs/otel/metrics/sdk/#view). For example, the following
configuration updates the metric named `otelcol_process_uptime` to emit a new
name `process_uptime` and description:
> [!NOTE]
>
> When configuring the Prometheus exporter for internal metrics manually (using
> `readers`), `otelcol_process_uptime` may be exported as
> `otelcol_process_uptime_seconds_total` unless `without_type_suffix` and
> `without_units` are set to `true`. Use the `instrument_name` value
> `otelcol_process_uptime` (the OTLP name) in views regardless. To control
> Prometheus-specific suffixes, see [Unit suffixes](#unit-suffixes).
```yaml
service:
telemetry:
metrics:
views:
- selector:
instrument_name: otelcol_process_uptime
instrument_type:
stream:
name: process_uptime
description: The amount of time the Collector has been up
```
You can also use `views` to update the resulting aggregation, attributes, and
cardinality limits. For the full list of options, see the examples in the
OpenTelemetry Configuration schema
[repository](https://github.com/open-telemetry/opentelemetry-configuration/blob/main/snippets/View_kitchen_sink.yaml).
### Configure internal logs
Log output is found in `stderr`. You can configure logs in the config
`service::telemetry::logs`. The
[configuration options](https://github.com/open-telemetry/opentelemetry-collector/blob/main/service/telemetry/otelconftelemetry/config.go)
are:
| Field name | Default value | Description |
| ---------------------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `level` | `INFO` | Sets the minimum enabled logging level. Other possible values are `DEBUG`, `WARN`, and `ERROR`. |
| `development` | `false` | Puts the logger in development mode. |
| `encoding` | `console` | Sets the logger's encoding. The other possible value is `json`. |
| `disable_caller` | `false` | Stops annotating logs with the calling function's file name and line number. By default, all logs are annotated. |
| `disable_stacktrace` | `false` | Disables automatic stacktrace capturing. Stacktraces are captured for logs at `WARN` level and above in development and at `ERROR` level and above in production. |
| `sampling::enabled` | `true` | Sets a sampling policy. |
| `sampling::tick` | `10s` | The interval in seconds that the logger applies to each sampling. |
| `sampling::initial` | `10` | The number of messages logged at the start of each `sampling::tick`. |
| `sampling::thereafter` | `100` | Sets the sampling policy for subsequent messages after `sampling::initial` messages are logged. When `sampling::thereafter` is set to `N`, every `Nth` message is logged and all others are dropped. If `N` is zero, the logger drops all messages after `sampling::initial` messages are logged. |
| `output_paths` | `["stderr"]` | A list of URLs or file paths to write logging output to. |
| `error_output_paths` | `["stderr"]` | A list of URLs or file paths to write logger errors to. |
| `initial_fields` | | A collection of static key-value pairs added to all log entries to enrich logging context. By default, there is no initial field. |
You can also see logs for the Collector on a Linux systemd system using
`journalctl`:
journalctl | grep otelcol
journalctl | grep otelcol | grep Error
The following configuration can be used to emit internal logs from the Collector
to an OTLP/HTTP backend:
```yaml
service:
telemetry:
logs:
processors:
- batch:
exporter:
otlp:
protocol: http/protobuf
endpoint: https://backend:4318
```
### Configure internal traces
The Collector does not expose traces by default, but it can be configured to.
> [!CAUTION]
>
> Internal tracing is an experimental feature, and no guarantees are made as to
> the stability of the emitted span names and attributes.
The following configuration can be used to emit internal traces from the
Collector to an OTLP backend:
```yaml
service:
telemetry:
traces:
processors:
- batch:
exporter:
otlp:
protocol: http/protobuf
endpoint: https://backend:4318
```
See the [example configuration][kitchen-sink-config] for additional options.
Note that the `tracer_provider` section there corresponds to `traces` here.
[kitchen-sink-config]:
https://github.com/open-telemetry/opentelemetry-configuration/blob/v0.3.0/examples/kitchen-sink.yaml
## Types of internal telemetry
The OpenTelemetry Collector aims to be a model of observable service by clearly
exposing its own operational metrics. Additionally, it collects host resource
metrics that can help you understand if problems are caused by a different
process on the same host. Specific components of the Collector can also emit
their own custom telemetry. In this section, you will learn about the different
types of observability emitted by the Collector itself.
### Summary of values observable with internal metrics
The Collector emits internal metrics for at least the following values:
- Process uptime and CPU time since start.
- Process memory and heap usage.
- For receivers: Items accepted and refused, per data type.
- For processors: Incoming and outgoing items.
- For exporters: Items the exporter sent, failed to enqueue, and failed to send,
per data type.
- For exporters: Queue size and capacity.
- Count, duration, and size of HTTP/gRPC requests and responses.
A more detailed list is available in the following sections.
### Metric names
This section explains special naming conventions applied to some internal
metrics.
#### `otelcol_` prefix {#otelcol-prefix}
As of Collector v0.106.1, internal metric names are handled differently based on
their source:
- Metrics generated from Collector components are prefixed with `otelcol_`.
- Metrics generated from instrumentation libraries do not use the `otelcol_`
prefix by default, unless their metric names are explicitly prefixed.
For Collector versions prior to v0.106.1, all internal metrics emitted using the
Prometheus exporter, regardless of their origin, are prefixed with `otelcol_`.
This includes metrics from both Collector components and instrumentation
libraries.
#### `_total` suffix {#total-suffix}
By default and unique to Prometheus, the Prometheus exporter adds a `_total`
suffix to summation metrics to follow Prometheus naming conventions, such as
`otelcol_exporter_send_failed_spans_total`. This behavior can be disabled by
setting `without_type_suffix: true` in the Prometheus exporter's configuration.
If you leave out `service::telemetry::metrics::readers` in the Collector
configuration, the default Prometheus exporter set up by the Collector already
has `without_type_suffix` set to `false`. However, if you customize the readers
and add a Prometheus exporter manually, you must set that option to return to
the "raw" metric name. For more information, see the
[Collector v1.25.0/v0.119.0 release notes](https://github.com/codeboten/opentelemetry-collector/blob/313167505b44e5dc9a29c0b9242cc4547db11ec3/CHANGELOG.md#v1250v01190).
Internal metrics exported through OTLP do not have this behavior. The
[internal metrics](#lists-of-internal-metrics) on this page are listed in OTLP
format, such as `otelcol_exporter_send_failed_spans`.
#### `_seconds` and other unit suffixes {#unit-suffixes}
The Prometheus exporter appends a unit suffix to metrics that carry a unit. For
example, `otelcol_process_uptime` (unit: seconds) can be exported as
`otelcol_process_uptime_seconds_total` — the `_seconds` unit suffix is added
first, then the `_total` counter suffix.
The default Prometheus exporter configured by the Collector (when no `readers`
are specified) already sets `without_type_suffix` and `without_units` to `true`
for backwards compatibility, so `otelcol_process_uptime` is used as-is.
However, when you manually configure the Prometheus exporter under
`service::telemetry::metrics::readers`, those options are not set by default. To
keep the original, shorter metric names, explicitly set both options to `true`:
```yaml
service:
telemetry:
metrics:
readers:
- pull:
exporter:
prometheus:
host: '0.0.0.0'
port: 8888
without_type_suffix: true
without_units: true
```
With this configuration, `otelcol_process_uptime_seconds_total` is exported as
`otelcol_process_uptime`.
#### Dots (`.`) v. underscores (`_`) {#dots-v-underscores}
`http*` and `rpc*` metrics come from instrumentation libraries. Their original
names used dots (`.`). Prior to Collector v0.120.0, internal metrics exposed
with Prometheus changed dots (`.`) to underscores (`_`) to match Prometheus
naming conventions, resulting in metric names that looked like
`rpc_server_duration`.
Versions 0.120.0 and later of the Collector use Prometheus 3.0 scrapers, so the
original `http*` and `rpc*` metric names with dots are preserved. The
[internal metrics](#lists-of-internal-metrics) on this page are listed in their
original form, such as`rpc.server.duration`. For more information, see the
[Collector v0.120.0 release notes](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/CHANGELOG.md#v01200).
### Lists of internal metrics
The following tables group each internal metric by level of verbosity: `basic`,
`normal`, and `detailed`. Each metric is identified by name and description and
categorized by instrumentation type.
#### `basic`-level metrics
| Metric name | Description | Type |
| ------------------------------------------------------ | --------------------------------------------------------------------------------------- | ------- |
| `otelcol_exporter_enqueue_failed_` `log_records` | Number of logs that exporter(s) failed to enqueue. | Counter |
| `otelcol_exporter_enqueue_failed_` `metric_points` | Number of metric points that exporter(s) failed to enqueue. | Counter |
| `otelcol_exporter_enqueue_failed_` `spans` | Number of spans that exporter(s) failed to enqueue. | Counter |
| `otelcol_exporter_queue_capacity` | Fixed capacity of the sending queue, in batches. | Gauge |
| `otelcol_exporter_queue_size` | Current size of the sending queue, in batches. | Gauge |
| `otelcol_exporter_send_failed_` `log_records` | Number of logs that exporter(s) failed to send to destination. | Counter |
| `otelcol_exporter_send_failed_` `metric_points` | Number of metric points that exporter(s) failed to send to destination. | Counter |
| `otelcol_exporter_send_failed_` `spans` | Number of spans that exporter(s) failed to send to destination. | Counter |
| `otelcol_exporter_sent_log_records` | Number of logs successfully sent to destination. | Counter |
| `otelcol_exporter_sent_metric_points` | Number of metric points successfully sent to destination. | Counter |
| `otelcol_exporter_sent_spans` | Number of spans successfully sent to destination. | Counter |
| `otelcol_process_cpu_seconds` | Total CPU user and system time in seconds. | Counter |
| `otelcol_process_memory_rss` | Total physical memory (resident set size) in bytes. | Gauge |
| `otelcol_process_runtime_heap_` `alloc_bytes` | Bytes of allocated heap objects (see 'go doc runtime.MemStats.HeapAlloc'). | Gauge |
| `otelcol_process_runtime_total_` `alloc_bytes` | Cumulative bytes allocated for heap objects (see 'go doc runtime.MemStats.TotalAlloc'). | Counter |
| `otelcol_process_runtime_total_` `sys_memory_bytes` | Total bytes of memory obtained from the OS (see 'go doc runtime.MemStats.Sys'). | Gauge |
| `otelcol_process_uptime` | Uptime of the process in seconds. | Counter |
| `otelcol_processor_incoming_items` | Number of items passed to the processor. | Counter |
| `otelcol_processor_outgoing_items` | Number of items emitted from the processor. | Counter |
| `otelcol_receiver_accepted_` `log_records` | Number of logs successfully ingested and pushed into the pipeline. | Counter |
| `otelcol_receiver_accepted_` `metric_points` | Number of metric points successfully ingested and pushed into the pipeline. | Counter |
| `otelcol_receiver_accepted_spans` | Number of spans successfully ingested and pushed into the pipeline. | Counter |
| `otelcol_receiver_refused_` `log_records` | Number of logs that could not be pushed into the pipeline. | Counter |
| `otelcol_receiver_refused_` `metric_points` | Number of metric points that could not be pushed into the pipeline. | Counter |
| `otelcol_receiver_refused_spans` | Number of spans that could not be pushed into the pipeline. | Counter |
| `otelcol_scraper_errored_` `metric_points` | Number of metric points the Collector failed to scrape. | Counter |
| `otelcol_scraper_scraped_` `metric_points` | Number of metric points scraped by the Collector. | Counter |
#### Additional `normal`-level metrics
| Metric name | Description | Type |
| ------------------------------------------------------- | --------------------------------------------------------------- | --------- |
| `otelcol_processor_batch_batch_` `send_size` | Number of units in the batch that was sent. | Histogram |
| `otelcol_processor_batch_batch_size_` `trigger_send` | Number of times the batch was sent due to a size trigger. | Counter |
| `otelcol_processor_batch_metadata_` `cardinality` | Number of distinct metadata value combinations being processed. | Counter |
| `otelcol_processor_batch_timeout_` `trigger_send` | Number of times the batch was sent due to a timeout trigger. | Counter |
> [!NOTE] Batch processor metrics level changes
>
> In Collector [v0.99.0][], all batch processor metrics were upgraded from
> `basic` to `normal` (current level), except for
> `otelcol_processor_batch_batch_send_size_bytes`, which has been `detailed`
> since its introduction. Note however that these metrics were inadvertently
> reverted to `basic` from v0.109.0 to v0.121.0.
[v0.99.0]:
https://github.com/open-telemetry/opentelemetry-collector/releases/tag/v0.99.0
#### Additional `detailed`-level metrics
| Metric name | Description | Type |
| ----------------------------------------------------- | ----------------------------------------------------------------------------------------- | --------- |
| `http.client.request.body.size` | Measures the size of HTTP client request bodies. | Counter |
| `http.client.request.duration` | Measures the duration of HTTP client requests. | Histogram |
| `http.server.request.body.size` | Measures the size of HTTP server request bodies. | Counter |
| `http.server.request.duration` | Measures the duration of HTTP server requests. | Histogram |
| `http.server.response.body.size` | Measures the size of HTTP server response bodies. | Counter |
| `otelcol_processor_batch_batch_` `send_size_bytes` | Number of bytes in the batch that was sent. | Histogram |
| `rpc.client.duration` | Measures the duration of outbound RPC. | Histogram |
| `rpc.client.request.size` | Measures the size of RPC request messages (uncompressed). | Histogram |
| `rpc.client.requests_per_rpc` | Measures the number of messages received per RPC. Should be 1 for all non-streaming RPCs. | Histogram |
| `rpc.client.response.size` | Measures the size of RPC response messages (uncompressed). | Histogram |
| `rpc.client.responses_per_rpc` | Measures the number of messages sent per RPC. Should be 1 for all non-streaming RPCs. | Histogram |
| `rpc.server.duration` | Measures the duration of inbound RPC. | Histogram |
| `rpc.server.request.size` | Measures the size of RPC request messages (uncompressed). | Histogram |
| `rpc.server.requests_per_rpc` | Measures the number of messages received per RPC. Should be 1 for all non-streaming RPCs. | Histogram |
| `rpc.server.response.size` | Measures the size of RPC response messages (uncompressed). | Histogram |
| `rpc.server.responses_per_rpc` | Measures the number of messages sent per RPC. Should be 1 for all non-streaming RPCs. | Histogram |
> [!NOTE]
>
> The `http*` and `rpc*` metrics are not covered by the maturity levels below
> since they are not under the Collector SIG control.
>
> The `otelcol_processor_batch_` metrics are unique to the `batchprocessor`.
>
> The `otelcol_receiver_`, `otelcol_scraper_`, `otelcol_processor_`, and
> `otelcol_exporter_` metrics come from their respective `helper` packages. As
> such, some components not using those packages might not emit them.
### Events observable with internal logs
The Collector logs the following internal events:
- A Collector instance starts or stops.
- Data dropping begins due to throttling for a specified reason, such as local
saturation, downstream saturation, downstream unavailable, etc.
- Data dropping due to throttling stops.
- Data dropping begins due to invalid data. A sample of the invalid data is
included.
- Data dropping due to invalid data stops.
- A crash is detected, differentiated from a clean stop. Crash data is included
if available.
## Telemetry maturity levels
The Collector telemetry levels apply to all first-party telemetry produced by
the Collector. Third-party libraries, including those of OpenTelemetry Go, are
not covered by these maturity levels.
### Traces
Tracing instrumentation is still under active development, and changes might be
made to span names, attached attributes, instrumented endpoints, or other
aspects of the telemetry. Until this feature graduates to stable, there are no
guarantees of backwards compatibility for tracing instrumentation.
### Metrics
The Collector's first-party metrics follow this lifecycle:
```mermaid
stateDiagram-v2
state StabilityLevels {
InDevelopment --> Alpha
Alpha --> Beta
Beta --> Stable
}
InDevelopment: In Development
StabilityLevels --> Deprecated
Deprecated --> Removed
```
The stability levels follow Semantic Conventions [guidance][SemConvGuidance],
derived from [OTEP-0232][OTEP-0232]. Collector metrics skip the
`release_candidate` level.
Note that the deprecated and deleted stages are lifecycle states, not stability
levels.
Third-party metrics, including those generated by OpenTelemetry Go
instrumentation libraries, are not covered by these maturity levels.
#### Development
Development metrics are still under active development and may change in any
release.
#### Alpha
Alpha metrics have no stability guarantees. These metrics can be modified or
deleted at any time.
#### Beta
Beta metrics may still change between releases, but component owners should try
to minimize breaking changes. This stage encourages broader usage and is the
final step before `stable`.
#### Stable
Stable metrics are guaranteed to not change. This means:
- A stable metric without a deprecated signature will not be deleted or renamed.
- A stable metric's type and attributes will not be modified.
#### Deprecated
Deprecated metrics are slated for deletion but are still available for use. The
description of these metrics include an annotation about the version in which
they became deprecated. For example:
Before deprecation:
```sh
# HELP otelcol_exporter_queue_size this counts things
# TYPE otelcol_exporter_queue_size counter
otelcol_exporter_queue_size 0
```
After deprecation:
```sh
# HELP otelcol_exporter_queue_size (Deprecated since 1.15.0) this counts things
# TYPE otelcol_exporter_queue_size counter
otelcol_exporter_queue_size 0
```
#### Deleted
Deleted metrics are no longer published and cannot be used.
### Logs
Individual log entries and their formatting might change from one release to the
next. There are no stability guarantees at this time.
## Use internal telemetry to monitor the Collector
This section recommends best practices for monitoring the Collector using its
own telemetry.
### Monitoring
#### Queue length
Most exporters provide a
[queue and/or retry mechanism](https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/exporterhelper/README.md)
that is recommended for use in any production deployment of the Collector.
The `otelcol_exporter_queue_capacity` metric indicates the capacity, in batches,
of the sending queue. The `otelcol_exporter_queue_size` metric indicates the
current size of the sending queue. Use these two metrics to check if the queue
capacity can support your workload.
Using the following three metrics, you can identify the number of spans, metric
points, and log records that failed to reach the sending queue:
- `otelcol_exporter_enqueue_failed_spans`
- `otelcol_exporter_enqueue_failed_metric_points`
- `otelcol_exporter_enqueue_failed_log_records`
These failures could be caused by a queue filled with unsettled elements. You
might need to decrease your sending rate or horizontally scale Collectors.
The queue or retry mechanism also supports logging for monitoring. Check the
logs for messages such as `Dropping data because sending_queue is full`.
#### Receive failures
Sustained rates of `otelcol_receiver_refused_log_records`,
`otelcol_receiver_refused_spans`, and `otelcol_receiver_refused_metric_points`
indicate that too many errors were returned to clients. Depending on the
deployment and the clients' resilience, this might indicate clients' data loss.
Sustained rates of `otelcol_exporter_send_failed_log_records`,
`otelcol_exporter_send_failed_spans`, and
`otelcol_exporter_send_failed_metric_points` indicate that the Collector is not
able to export data as expected. These metrics do not inherently imply data loss
since there could be retries. But a high rate of failures could indicate issues
with the network or backend receiving the data.
#### Data flow
You can monitor data ingress with the `otelcol_receiver_accepted_log_records`,
`otelcol_receiver_accepted_spans`, and `otelcol_receiver_accepted_metric_points`
metrics and data egress with the `otelcol_exporter_sent_log_records`,
`otelcol_exporter_sent_spans`, and `otelcol_exporter_sent_metric_points`
metrics.
[SemConvGuidance]:
/docs/specs/semconv/general/semantic-convention-groups#group-stability
[OTEP-0232]:
https://github.com/open-telemetry/opentelemetry-specification/blob/v1.50.0/oteps/0232-maturity-of-otel.md