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---
stage: Analytics
group: Product Intelligence
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
---
# Metrics instrumentation guide
This guide describes how to develop Service Ping metrics using metrics instrumentation.
<i class="fa fa-youtube-play youtube" aria-hidden="true"></i>
For a video tutorial, see the [Adding Service Ping metric via instrumentation class](https://youtu.be/p2ivXhNxUoY).
## Nomenclature
- **Instrumentation class**:
- Inherits one of the metric classes: `DatabaseMetric`, `RedisMetric`, `RedisHLLMetric`, `NumbersMetric` or `GenericMetric`.
- Implements the logic that calculates the value for a Service Ping metric.
- **Metric definition**
The Service Data metric YAML definition.
- **Hardening**:
Hardening a method is the process that ensures the method fails safe, returning a fallback value like -1.
## How it works
A metric definition has the [`instrumentation_class`](metrics_dictionary.md) field, which can be set to a class.
The defined instrumentation class should inherit one of the existing metric classes: `DatabaseMetric`, `RedisMetric`, `RedisHLLMetric`, `NumbersMetric` or `GenericMetric`.
The current convention is that a single instrumentation class corresponds to a single metric. On rare occasions, there are exceptions to that convention like [Redis metrics](#redis-metrics). To use a single instrumentation class for more than one metric, please reach out to one of the `@gitlab-org/analytics-section/product-intelligence/engineers` members to consult about your case.
Using the instrumentation classes ensures that metrics can fail safe individually, without breaking the entire
process of Service Ping generation.
We have built a domain-specific language (DSL) to define the metrics instrumentation.
## Database metrics
You can use database metrics to track data kept in the database, for example, a count of issues that exist on a given instance.
- `operation`: Operations for the given `relation`, one of `count`, `distinct_count`, `sum`, and `average`.
- `relation`: Assigns lambda that returns the `ActiveRecord::Relation` for the objects we want to perform the `operation`. The assigned lambda can accept up to one parameter. The parameter is hashed and stored under the `options` key in the metric definition.
- `start`: Specifies the start value of the batch counting, by default is `relation.minimum(:id)`.
- `finish`: Specifies the end value of the batch counting, by default is `relation.maximum(:id)`.
- `cache_start_and_finish_as`: Specifies the cache key for `start` and `finish` values and sets up caching them. Use this call when `start` and `finish` are expensive queries that should be reused between different metric calculations.
- `available?`: Specifies whether the metric should be reported. The default is `true`.
- `timestamp_column`: Optionally specifies timestamp column for metric used to filter records for time constrained metrics. The default is `created_at`.
[Example of a merge request that adds a database metric](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/60022).
```ruby
module Gitlab
module Usage
module Metrics
module Instrumentations
class CountIssuesMetric < DatabaseMetric
operation :count
relation ->(options) { Issue.where(confidential: options[:confidential]) }
end
end
end
end
end
```
### Ordinary batch counters Example
```ruby
module Gitlab
module Usage
module Metrics
module Instrumentations
class CountIssuesMetric < DatabaseMetric
operation :count
start { Issue.minimum(:id) }
finish { Issue.maximum(:id) }
relation { Issue }
end
end
end
end
end
```
### Distinct batch counters Example
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class CountUsersAssociatingMilestonesToReleasesMetric < DatabaseMetric
operation :distinct_count, column: :author_id
relation { Release.with_milestones }
start { Release.minimum(:author_id) }
finish { Release.maximum(:author_id) }
end
end
end
end
end
```
### Sum Example
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class JiraImportsTotalImportedIssuesCountMetric < DatabaseMetric
operation :sum, column: :imported_issues_count
relation { JiraImportState.finished }
end
end
end
end
end
```
### Average Example
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class CountIssuesWeightAverageMetric < DatabaseMetric
operation :average, column: :weight
relation { Issue }
end
end
end
end
end
```
## Redis metrics
You can use Redis metrics to track events not kept in the database, for example, a count of how many times the search bar has been used.
[Example of a merge request that adds a `Redis` metric](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/97009).
Please note that `RedisMetric` class can only be used as the `instrumentation_class` for Redis metrics with simple counters classes (classes that only inherit `BaseCounter` and set `PREFIX` and `KNOWN_EVENTS` constants). In case the counter class has additional logic included in it, a new `instrumentation_class`, inheriting from `RedisMetric`, needs to be created. This new class needs to include the additional logic from the counter class.
Count unique values for `source_code_pushes` event.
Required options:
- `event`: the event name.
- `prefix`: the value of the `PREFIX` constant used in the counter classes from the `Gitlab::UsageDataCounters` namespace.
```yaml
time_frame: all
data_source: redis
instrumentation_class: RedisMetric
options:
event: pushes
prefix: source_code
```
### Availability-restrained Redis metrics
If the Redis metric should only be available in the report under some conditions, then you must specify these conditions in a new class that is a child of the `RedisMetric` class.
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class MergeUsageCountRedisMetric < RedisMetric
available? { Feature.enabled?(:merge_usage_data_missing_key_paths) }
end
end
end
end
end
```
You must also use the class's name in the YAML setup.
```yaml
time_frame: all
data_source: redis
instrumentation_class: MergeUsageCountRedisMetric
options:
event: pushes
prefix: source_code
```
## Redis HyperLogLog metrics
You can use Redis HyperLogLog metrics to track events not kept in the database and incremented for unique values such as unique users,
for example, a count of how many different users used the search bar.
[Example of a merge request that adds a `RedisHLL` metric](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/61685).
Count unique values for `i_quickactions_approve` event.
```yaml
time_frame: 28d
data_source: redis_hll
instrumentation_class: RedisHLLMetric
options:
events:
- i_quickactions_approve
```
### Availability-restrained Redis HyperLogLog metrics
If the Redis HyperLogLog metric should only be available in the report under some conditions, then you must specify these conditions in a new class that is a child of the `RedisHLLMetric` class.
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class MergeUsageCountRedisHLLMetric < RedisHLLMetric
available? { Feature.enabled?(:merge_usage_data_missing_key_paths) }
end
end
end
end
end
```
You must also use the class's name in the YAML setup.
```yaml
time_frame: 28d
data_source: redis_hll
instrumentation_class: MergeUsageCountRedisHLLMetric
options:
events:
- i_quickactions_approve
```
## Aggregated metrics
<div class="video-fallback">
See the video from: <a href="https://www.youtube.com/embed/22LbYqHwtUQ">Product Intelligence Office Hours Oct 6th</a> for an aggregated metrics walk-through.
</div>
<figure class="video-container">
<iframe src="https://www.youtube.com/embed/22LbYqHwtUQ" frameborder="0" allowfullscreen="true"> </iframe>
</figure>
The aggregated metrics feature provides insight into the number of data attributes, for example `pseudonymized_user_ids`, that occurred in a collection of events. For example, you can aggregate the number of users who perform multiple actions such as creating a new issue and opening
a new merge request.
You can use a YAML file to define your aggregated metrics. The following arguments are required:
- `options.events`: List of event names to aggregate into metric data. All events in this list must
use the same data source. Additional data source requirements are described in
[Database sourced aggregated metrics](implement.md#database-sourced-aggregated-metrics) and
[Redis sourced aggregated metrics](implement.md#redis-sourced-aggregated-metrics).
- `options.aggregate.operator`: Operator that defines how the aggregated metric data is counted. Available operators are:
- `OR`: Removes duplicates and counts all entries that triggered any of the listed events.
- `AND`: Removes duplicates and counts all elements that were observed triggering all of the following events.
- `options.aggregate.attribute`: Information pointing to the attribute that is being aggregated across events.
- `time_frame`: One or more valid time frames. Use these to limit the data included in aggregated metrics to events within a specific date-range. Valid time frames are:
- `7d`: The last 7 days of data.
- `28d`: The last 28 days of data.
- `all`: All historical data, only available for `database` sourced aggregated metrics.
- `data_source`: Data source used to collect all events data included in the aggregated metrics. Valid data sources are:
- [`database`](implement.md#database-sourced-aggregated-metrics)
- [`redis_hll`](implement.md#redis-sourced-aggregated-metrics)
Refer to merge request [98206](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/98206) for an example of a merge request that adds an `AggregatedMetric` metric.
Count unique `user_ids` that occurred in at least one of the events: `incident_management_alert_status_changed`,
`incident_management_alert_assigned`, `incident_management_alert_todo`, `incident_management_alert_create_incident`.
```yaml
time_frame: 28d
instrumentation_class: AggregatedMetric
data_source: redis_hll
options:
aggregate:
operator: OR
attribute: user_id
events:
- `incident_management_alert_status_changed`
- `incident_management_alert_assigned`
- `incident_management_alert_todo`
- `incident_management_alert_create_incident`
```
### Availability-restrained Aggregated metrics
If the Aggregated metric should only be available in the report under specific conditions, then you must specify these conditions in a new class that is a child of the `AggregatedMetric` class.
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class MergeUsageCountAggregatedMetric < AggregatedMetric
available? { Feature.enabled?(:merge_usage_data_missing_key_paths) }
end
end
end
end
end
```
You must also use the class's name in the YAML setup.
```yaml
time_frame: 28d
instrumentation_class: MergeUsageCountAggregatedMetric
data_source: redis_hll
options:
aggregate:
operator: OR
attribute: user_id
events:
- `incident_management_alert_status_changed`
- `incident_management_alert_assigned`
- `incident_management_alert_todo`
- `incident_management_alert_create_incident`
```
## Numbers metrics
- `operation`: Operations for the given `data` block. Currently we only support `add` operation.
- `data`: a `block` which contains an array of numbers.
- `available?`: Specifies whether the metric should be reported. The default is `true`.
```ruby
# frozen_string_literal: true
module Gitlab
module Usage
module Metrics
module Instrumentations
class IssuesBoardsCountMetric < NumbersMetric
operation :add
data do |time_frame|
[
CountIssuesMetric.new(time_frame: time_frame).value,
CountBoardsMetric.new(time_frame: time_frame).value
]
end
end
end
end
end
end
end
```
You must also include the instrumentation class name in the YAML setup.
```yaml
time_frame: 28d
instrumentation_class: IssuesBoardsCountMetric
```
## Generic metrics
You can use generic metrics for other metrics, for example, an instance's database version. Observations type of data will always have a Generic metric counter type.
- `value`: Specifies the value of the metric.
- `available?`: Specifies whether the metric should be reported. The default is `true`.
[Example of a merge request that adds a generic metric](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/60256).
```ruby
module Gitlab
module Usage
module Metrics
module Instrumentations
class UuidMetric < GenericMetric
value do
Gitlab::CurrentSettings.uuid
end
end
end
end
end
end
```
## Support for instrumentation classes
There is support for:
- `count`, `distinct_count`, `estimate_batch_distinct_count`, `sum`, and `average` for [database metrics](#database-metrics).
- [Redis metrics](#redis-metrics).
- [Redis HLL metrics](#redis-hyperloglog-metrics).
- `add` for [numbers metrics](#numbers-metrics).
- [Generic metrics](#generic-metrics), which are metrics based on settings or configurations.
There is no support for:
- `add`, `histogram` for database metrics.
You can [track the progress to support these](https://gitlab.com/groups/gitlab-org/-/epics/6118).
## Create a new metric instrumentation class
To create a stub instrumentation for a Service Ping metric, you can use a dedicated [generator](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/generators/gitlab/usage_metric_generator.rb):
The generator takes the class name as an argument and the following options:
- `--type=TYPE` Required. Indicates the metric type. It must be one of: `database`, `generic`, `redis`, `numbers`.
- `--operation` Required for `database` & `numbers` type.
- For `database` it must be one of: `count`, `distinct_count`, `estimate_batch_distinct_count`, `sum`, `average`.
- For `numbers` it must be: `add`.
- `--ee` Indicates if the metric is for EE.
```shell
rails generate gitlab:usage_metric CountIssues --type database --operation distinct_count
create lib/gitlab/usage/metrics/instrumentations/count_issues_metric.rb
create spec/lib/gitlab/usage/metrics/instrumentations/count_issues_metric_spec.rb
```
## Migrate Service Ping metrics to instrumentation classes
This guide describes how to migrate a Service Ping metric from [`lib/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/usage_data.rb) or [`ee/lib/ee/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/ee/gitlab/usage_data.rb) to instrumentation classes.
1. Choose the metric type:
- [Database metric](#database-metrics)
- [Redis HyperLogLog metrics](#redis-hyperloglog-metrics)
- [Redis metric](#redis-metrics)
- [Numbers metric](#numbers-metrics)
- [Generic metric](#generic-metrics)
1. Determine the location of instrumentation class: either under `ee` or outside `ee`.
1. [Generate the instrumentation class file](#create-a-new-metric-instrumentation-class).
1. Fill the instrumentation class body:
- Add code logic for the metric. This might be similar to the metric implementation in `usage_data.rb`.
- Add tests for the individual metric [`spec/lib/gitlab/usage/metrics/instrumentations/`](https://gitlab.com/gitlab-org/gitlab/-/tree/master/lib/gitlab/usage/metrics/instrumentations).
- Add tests for Service Ping.
1. [Generate the metric definition file](metrics_dictionary.md#create-a-new-metric-definition).
1. Remove the code from [`lib/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/usage_data.rb) or [`ee/lib/ee/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/ee/gitlab/usage_data.rb).
1. Remove the tests from [`spec/lib/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/lib/gitlab/usage_data_spec.rb) or [`ee/spec/lib/ee/gitlab/usage_data.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/spec/lib/ee/gitlab/usage_data_spec.rb).
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