Span Metrics connector ๐
The Splunk Distribution of the OpenTelemetry Collector uses the Span Metrics connector to aggregate requests, errors and duration (R.E.D) OpenTelemetry metrics from span data.
As an exporter, the supported pipeline type is traces
. As a receiver, the supported pipeline type is metrics
. See Process your data with pipelines for more information.
Overview ๐
The connector pulls span data and aggregates them into Request, Error and Duration (R.E.D) OpenTelemetry metrics.
Requests ๐
Request counts are computed as the number of spans seen per unique set of dimensions, including Errors. Multiple metrics can be aggregated if, for instance, you wish to view call counts just on service.name
and span.name
.
calls{service.name="shipping",span.name="get_shipping/{shippingId}",span.kind="SERVER",status.code="Ok"}
Errors ๐
Error counts are computed from the Request counts which have an Error Status Code metric dimension.
calls{service.name="shipping",span.name="get_shipping/{shippingId},span.kind="SERVER",status.code="Error"}
Duration ๐
Duration is computed from the difference between the span start and end times and inserted into the relevant duration histogram time bucket for each unique set dimensions.
duration{service.name="shipping",span.name="get_shipping/{shippingId}",span.kind="SERVER",status.code="Ok"}
Common dimensions for metrics ๐
Each metric has at least the following dimensions because they are common across all spans:
service.name
span.name
span.kind
status.code
Get started ๐
Follow these steps to configure and activate the component:
Deploy the Splunk Distribution of the OpenTelemetry Collector to your host or container platform:
Configure the connector as described in the next section.
Restart the Collector.
Sample configuration ๐
To activate the resource processor, add spanmetrics
to the connectors
section of your configuration file.
For example:
receivers:
nop:
exporters:
nop:
connectors:
spanmetrics:
histogram:
explicit:
buckets: [100us, 1ms, 2ms, 6ms, 10ms, 100ms, 250ms]
dimensions:
- name: http.method
default: GET
- name: http.status_code
exemplars:
enabled: true
exclude_dimensions: ['status.code']
dimensions_cache_size: 1000
aggregation_temporality: "AGGREGATION_TEMPORALITY_CUMULATIVE"
metrics_flush_interval: 15s
metrics_expiration: 5m
events:
enabled: true
dimensions:
- name: exception.type
- name: exception.message
resource_metrics_key_attributes:
- service.name
- telemetry.sdk.language
- telemetry.sdk.name
To complete the configuration, in the service
section of your configuration file, include the connector as an exporter in the traces
pipeline and as a receiver in the metrics
pipeline.
For example:
service:
pipelines:
traces:
receivers: [nop]
exporters: [spanmetrics]
metrics:
receivers: [spanmetrics]
exporters: [nop]
Configuration options ๐
The following settings can be optionally configured:
histogram
.explicit
by default. Use it to configure the type of histogram to record calculated from spans duration measurements. Must be eitherexplicit
orexponential
.disable
.false
by default. Disables all histogram metrics.unit
.ms
by default. The time unit for recording duration measurements, calculated from spans duration measurements. Possible values arms
ors
.explicit
:buckets
. The list of durations defining the duration histogram time buckets. Default buckets:[2ms, 4ms, 6ms, 8ms, 10ms, 50ms, 100ms, 200ms, 400ms, 800ms, 1s, 1400ms, 2s, 5s, 10s, 15s]
.
exponential
:max_size
.160
by default. The maximum number of buckets per positive or negative number range.
dimensions
. The list of dimensions to add together with the default dimensions defined above.Each additional dimension is defined with a name which is looked up in the spanโs collection of attributes or resource attributes (process tags) such as
ip
,host.name
orregion
.If the
named
attribute is missing in the span, the optional provided default is used.If no default is provided, this dimension will be omitted from the metric.
exclude_dimensions
. The list of dimensions to be excluded from the default set of dimensions. Use to exclude unneeded data from metrics.dimensions_cache_size
.1000
by default. The size of cache for storing Dimensions to improve Collectorsโ memory usage. Must be a positive number.resource_metrics_cache_size
.1000
by default. The size of the cache holding metrics for a service. This is mostly relevant for cumulative temporality to avoid memory leaks and correct metric timestamp resets.aggregation_temporality
.AGGREGATION_TEMPORALITY_CUMULATIVE
by default. Defines the aggregation temporality of the generated metrics. Possible values areAGGREGATION_TEMPORALITY_CUMULATIVE
orAGGREGATION_TEMPORALITY_DELTA
.namespace
. Defines the namespace of the generated metrics. If a namespaceโs provided, the prefixnamespace.
is added to the generated metric name.metrics_flush_interval
.60
by default. Defines the flush interval of the generated metrics.metrics_expiration
.0
by default. Defines the expiration time astime.Duration
, after which, if no new spans are received, metrics will no longer be exported. If you set it to0
metrics will never expire.exemplars
. Use them to configure how to attach exemplars to metrics.enabled
.faulse
by default. Enabling it will add spans as Exemplars to all metrics. Exemplars are only kept for one flush interval.
events
. Use it to configure the events metric.enabled
.false
by default. Enabling it adds the events metric.dimensions
: Mandatory ifevents
is enabled. The list of the spanโs event attributes to add as dimensions to the events metric, which will be included on top of the common and configured dimensions for span and resource attributes.
resource_metrics_key_attributes
. Filter the resource attributes used to produce the resource metrics key map hash. Use this in case changing resource attributes (e.g. process id) are breaking counter metrics.
Migrate from the Span Metrics processor to the Span Metrics connector ๐
The spanmetrics
connector is a port of the Span processor, but with multiple improvements and breaking changes. It was done to bring the spanmetrics connector closer to the OpenTelemetry specification and make the component agnostic to exporters logic.
The connector comes with the following changes:
The
operation
metric attribute is renamed tospan.name
.The
latency
histogram metric name is changed toduration
.The
_total
metric prefix was dropped from generated metrics names.The Prometheus-specific metrics labels sanitization was dropped.
Other improvements include:
Added support for OTel exponential histograms for recording span duration measurements.
Added support for the milliseconds and seconds histogram units.
Added support for generating metrics resource scope attributes. The
spanmetrics
connector generates the number of metrics resource scopes that corresponds to the number of the spans resource scopes, so it generates more metrics. Previously,spanmetrics
generated a single metrics resource scope.
Use the Span Metrics connector with Prometheus components ๐
The spanmetrics
connector can be used with Prometheus exporter components such as Prometheus receiver.
For some functionality of the exporters, for example, to generate the target_info
metric, the incoming spans resource scope attributes must contain the service.name
and service.instance.id
attributes.
Letโs look at the example of using the spanmetrics
connector with the prometheusremotewrite
exporter:
receivers:
otlp:
protocols:
http:
grpc:
exporters:
prometheusremotewrite:
endpoint: http://localhost:9090/api/v1/write
target_info:
enabled: true
connectors:
spanmetrics:
namespace: span.metrics
service:
pipelines:
traces:
receivers: [otlp]
exporters: [spanmetrics]
metrics:
receivers: [spanmetrics]
exporters: [prometheusremotewrite]
This configures the spanmetrics
connector to generate metrics from received spans and export those metrics to the Prometheus Remote Write exporter. The target_info
metric is generated for each resource scope, while OpenTelemetry metric names and attributes are normalized to be compliant with Prometheus naming rules.
For example, the generated calls OTel sum metric can result in multiple Prometheus calls_total
(counter type) time series and the target_info
time series. See below:
target_info{job="shippingservice", instance="...", ...} 1
calls_total{span_name="/Address", service_name="shippingservice", span_kind="SPAN_KIND_SERVER", status_code="STATUS_CODE_UNSET", ...} 142
Settings ๐
The following table shows the configuration options for the spanmetrics
connector:
Troubleshooting ๐
If you are a Splunk Observability Cloud customer and are not able to see your data in Splunk Observability Cloud, you can get help in the following ways.
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Submit a case in the Splunk Support Portal .
Contact Splunk Support .
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Ask a question and get answers through community support at Splunk Answers .
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