metrics.yaml file

The metrics.yaml file defines what metrics and events your application will collect.

The top-level of the file must contain the following key-value pair to indicate that it is a Glean metrics.yaml file:

$schema: moz://mozilla.org/schemas/glean/metrics/1-0-0

The other keys at the top level of the file are category names. Category names must be in snake_case, but may also contain . to indicate ad hoc subcategories. Category names have a maximum of 40 characters.

Within each category, the individual metrics are defined. The key is the name of the metric (snake_case with a maximum of 30 characters), and each value is an object with the following parameters described below.

metrics.yaml files must be encoded in UTF-8.

Metric parameters

type

Required.

Specifies the type of a metric, like “counter” or “event”. This defines which operations are valid for the metric, how it is stored and how data analysis tooling displays it.

The supported types are:

  • event: Record a specific event (with optional metadata). Additional properties: extra_keys.

  • boolean: A metric storing values of true or false.

  • string: A metric storing Unicode string values.

  • string_list: a list of Unicode strings.

  • counter: A numeric value that can only be incremented.

  • quantity: A numeric value that is set directly.

  • timespan: Represents a time interval. Additional properties: time_unit.

  • timing_distribution: Record the distribution of multiple timings. Additional properties: time_unit.

  • datetime: A date/time value. Represented as an ISO datetime in UTC. Additional properties: time_unit.

  • uuid: Record a UUID v4.

  • jwe: Record a [JWE](https://tools.ietf.org/html/rfc7516) value.

  • memory_distribution: A histogram for recording memory usage values. Additional properties: memory_unit.

  • custom_distribution: A histogram with a custom range and number of buckets. This metric type is for legacy support only and is only allowed for metrics coming from GeckoView. Additional properties: range_min, range_max, bucket_count, histogram_type.

  • Additionally, labeled versions of many metric types are supported. These support the labels parameter, allowing multiple instances of the metric to be stored at a given set of labels. The labeled metric types include:

    labeled_boolean, labeled_string, labeled_counter.

description

Required.

A textual description of what this metric does, what it means, and its edge cases or any other helpful information.

Descriptions may contain markdown syntax.

notification_emails

Required.

A list of email addresses to notify for important events with the metric or when people with context or ownership for the metric need to be contacted.

bugs

Required.

A list of bug URLs (e.g. Bugzilla and Github) that are relevant to this metric, e.g., tracking its original implementation or later changes to it.

Using bug numbers alone is deprecated and will be an error in the future. Each entry should be a full URL to the bug in its tracker.

data_reviews

Required.

A list of URIs to any data collection reviews relevant to the metric.

lifetime

Defines the lifetime of the metric. It must be one of the following values:

  • ping (default): The metric is reset each time it is sent in a ping.

  • user: The metric contains a property that is part of the user’s profile and is never reset.

  • application: The metric contains a property that is related to the application, and is reset only at application restarts.

send_in_pings

Which pings the metric should be sent on. If not specified, the metric is sent on the “default ping”, which is the events ping for events, and the metrics ping for everything else. Most metrics don’t need to specify this.

(There is an additional special value of all-pings for internal Glean metrics only that is used to indicate that a metric may appear in any ping.)

disabled

If true, the metric is disabled, and any metric collection on it will be silently ignored at runtime.

expires

Required.

By default it may be one of the following values:

  • <build date>: An ISO date yyyy-mm-dd in UTC on which the metric expires. For example, 2019-03-13. This date is checked at build time. Except in special cases, this form should be used so that the metric automatically “sunsets” after a period of time.

  • never: This metric never expires.

  • expired: This metric is manually expired.

The default may be overriden in certain applications by the custom_validate_expires and custom_is_expired configs.

version

The version of the metric. A monotonically increasing value. If not provided, defaults to 0.

time_unit

For timespans and datetimes, specifies the unit that the metric will be stored and displayed in. If not provided, it defaults to “millisecond”. Time values are sent to the backend as integers, so time_unit determines the maximum resolution at which timespans are recorded. Times are always truncated, not rounded, to the nearest time unit. For example, a measurement of 25 ns will be returned as 0 ms if time_unit is "millisecond".

For timing distributions, times are always recorded and sent in nanoseconds, but time_unit controls the minimum and maximum values. If not provided, it defaults to “nanosecond”.

  • nanosecond: 1ns <= x <= 10 minutes

  • microsecond: 1μs <= x <= ~6.94 days

  • millisecond: 1ms <= x <= ~19 years

Valid when type is timespan, timing_distribution or datetime.

labels

A list of labels for a labeled metric. If provided, the labels are enforced at run time, and recording to an unknown label is recorded to the special label __other__. If not provided, the labels may be anything, but using too many unique labels will put some labels in the special label __other__.

Valid with any of the labeled metric types.

extra_keys

The acceptable keys on the “extra” object sent with events. This is an object mapping the key to an object containing metadata about the key. A maximum of 10 extra keys is allowed. This metadata object has the following keys:

  • description: Required. A description of the key.

Valid when type is event.

gecko_datapoint

This is a Gecko-specific property. It is the name of the Gecko metric to accumulate the data from, when using the Glean SDK in a product using GeckoView. See bug 1566356 for more context.

no_lint

This parameter lists any lint checks to skip for this metric only.

JSON Schema

There is a formal schema for validating metrics.yaml files, included in its entirety below:

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

---
$schema: http://json-schema.org/draft-07/schema#
title: Metrics
description: |
  Schema for the metrics.yaml files for Mozilla's Glean telemetry SDK.

  The top-level of the `metrics.yaml` file has a key defining each category of
  metrics. Categories must be snake_case, and they may also have dots `.` to
  define subcategories.

$id: moz://mozilla.org/schemas/glean/metrics/1-0-0

definitions:
  token:
    type: string
    pattern: "^[A-Za-z_][A-Za-z0-9_\\.]*$"

  snake_case:
    type: string
    pattern: "^[a-z_][a-z0-9_]*$"

  dotted_snake_case:
    type: string
    pattern: "^[a-z_][a-z0-9_]{0,29}(\\.[a-z_][a-z0-9_]{0,29})*$"
    maxLength: 40

  kebab_case:
    type: string
    # Bug 1601270; we allow 3 specific existing snake_cased ping names for now,
    # but these special cases can be removed once the number of legacy clients
    # sufficiently dwindles, likely in 2020H2.
    pattern: "^[a-z][a-z0-9-]{0,29}$\
      |^deletion_request$|^bookmarks_sync$|^history_sync$|^session_end$|^all_pings$|^glean_.*$"

  long_id:
    allOf:
      - $ref: "#/definitions/snake_case"
      - maxLength: 40

  short_id:
    allOf:
      - $ref: "#/definitions/snake_case"
      - maxLength: 30

  labeled_metric_id:
    type: string
    pattern: "^[a-z_][a-z0-9_-]{0,29}(\\.[a-z_][a-z0-9_-]{0,29})*$"
    maxLength: 71  # Note: this should be category + metric + 1

  metric:
    description: |
      Describes a single metric.

      See https://mozilla.github.io/glean_parser/metrics-yaml.html

    type: object

    additionalProperties: false

    properties:
      type:
        title: Metric type
        description: |
          **Required.**

          Specifies the type of a metric, like "counter" or "event". This
          defines which operations are valid for the metric, how it is stored
          and how data analysis tooling displays it.

          The supported types are:
            - `event`: Record a specific event (with optional metadata).
              Additional properties: `extra_keys`.

            - `boolean`: A metric storing values of true or false.

            - `string`: A metric storing Unicode string values.

            - `string_list`: a list of Unicode strings.

            - `counter`: A numeric value that can only be incremented.

            - `quantity`: A numeric value that is set directly.

            - `timespan`: Represents a time interval. Additional properties:
              `time_unit`.

            - `timing_distribution`: Record the distribution of multiple
              timings. Additional properties: `time_unit`.

            - `datetime`: A date/time value. Represented as an ISO datetime in
              UTC. Additional properties: `time_unit`.

            - `uuid`: Record a UUID v4.

            - `jwe`: Record a [JWE](https://tools.ietf.org/html/rfc7516) value.

            - `memory_distribution`: A histogram for recording memory usage
              values. Additional properties: `memory_unit`.

            - `custom_distribution`: A histogram with a custom range and number
              of buckets. This metric type is for legacy support only and is
              only allowed for metrics coming from GeckoView. Additional
              properties: `range_min`, `range_max`, `bucket_count`,
              `histogram_type`.

            - Additionally, labeled versions of many metric types are supported.
              These support the `labels`_ parameter, allowing multiple instances
              of the metric to be stored at a given set of labels. The labeled
              metric types include:

                `labeled_boolean`, `labeled_string`, `labeled_counter`.

        type: string
        enum:
          - event
          - boolean
          - string
          - string_list
          - counter
          - quantity
          - timespan
          - timing_distribution
          - custom_distribution
          - memory_distribution
          - datetime
          - uuid
          - jwe
          - labeled_boolean
          - labeled_string
          - labeled_counter

      description:
        title: Description
        description: |
          **Required.**

          A textual description of what this metric does, what it means, and its
          edge cases or any other helpful information.

          Descriptions may contain [markdown
          syntax](https://www.markdownguide.org/basic-syntax/).
        type: string

      lifetime:
        title: Lifetime
        description: |
          Defines the lifetime of the metric. It must be one of the following
          values:

          - `ping` (default): The metric is reset each time it is sent in a
            ping.

          - `user`: The metric contains a property that is part of the user's
            profile and is never reset.

          - `application`: The metric contains a property that is related to the
            application, and is reset only at application restarts.
        enum:
          - ping
          - user
          - application
        default: ping

      send_in_pings:
        title: Send in pings
        description: |
          Which pings the metric should be sent on. If not specified, the metric
          is sent on the "default ping", which is the `events` ping for events,
          and the `metrics` ping for everything else. Most metrics don't need to
          specify this.

          (There is an additional special value of `all-pings` for internal
          Glean metrics only that is used to indicate that a metric may appear
          in any ping.)
        type: array
        items:
          $ref: "#/definitions/kebab_case"
        default:
          - default

      notification_emails:
        title: Notification emails
        description: |
          **Required.**

          A list of email addresses to notify for important events with the
          metric or when people with context or ownership for the metric need to
          be contacted.
        type: array
        minItems: 1
        items:
          type: string
          format: email

      bugs:
        title: Related bugs
        description: |
          **Required.**

          A list of bug URLs (e.g. Bugzilla and Github) that are relevant to
          this metric, e.g., tracking its original implementation or later
          changes to it.

          Using bug numbers alone is deprecated and will be an error in the
          future. Each entry should be a full URL to the bug in its tracker.
        type: array
        minItems: 1
        items:
          anyOf:
            - type: integer
            - type: string
              format: uri

      data_reviews:
        title: Review references
        description: |
          **Required.**

          A list of URIs to any data collection reviews relevant to the metric.
        type: array
        items:
          type: string
          format: uri

      disabled:
        title: Disabled
        description: |
          If `true`, the metric is disabled, and any metric collection on it
          will be silently ignored at runtime.
        type: boolean
        default: false

      expires:
        title: Expires
        description: |
          **Required.**

          By default it may be one of the following values:
            - `<build date>`: An ISO date `yyyy-mm-dd` in UTC on which the
              metric expires. For example, `2019-03-13`. This date is checked at
              build time. Except in special cases, this form should be used so
              that the metric automatically "sunsets" after a period of time.
            - `never`: This metric never expires.
            - `expired`: This metric is manually expired.

          The default may be overriden in certain applications by the
          `custom_validate_expires` and `custom_is_expired` configs.
        type: string

      version:
        title: Metric version
        description: |
          The version of the metric. A monotonically increasing value. If not
          provided, defaults to 0.

      time_unit:
        title: Time unit
        description: |
          For timespans and datetimes, specifies the unit that the metric will
          be stored and displayed in. If not provided, it defaults to
          "millisecond". Time values are sent to the backend as integers, so
          `time_unit`_ determines the maximum resolution at which timespans are
          recorded. Times are always truncated, not rounded, to the nearest time
          unit. For example, a measurement of 25 ns will be returned as 0 ms if
          `time_unit` is `"millisecond"`.

          For timing distributions, times are always recorded and sent in
          nanoseconds, but `time_unit` controls the minimum and maximum values.
          If not provided, it defaults to "nanosecond".

          - nanosecond: 1ns <= x <= 10 minutes
          - microsecond: 1μs <= x <= ~6.94 days
          - millisecond: 1ms <= x <= ~19 years

          Valid when `type`_ is `timespan`, `timing_distribution` or `datetime`.
        enum:
          - nanosecond
          - microsecond
          - millisecond
          - second
          - minute
          - hour
          - day

      memory_unit:
        title: Memory unit
        description: |
          The unit that the incoming memory size values are recorded in.

          The units are the power-of-2 units, so "kilobyte" is correctly a
          "kibibyte".

          - kilobyte == 2^10 ==         1,024 bytes
          - megabyte == 2^20 ==     1,048,576 bytes
          - gigabyte == 2^30 == 1,073,741,824 bytes

          Values are automatically converted to and transmitted as bytes.

          Valid when `type`_ is `memory_distribution`.
        enum:
          - byte
          - kilobyte
          - megabyte
          - gigabyte

      labels:
        title: Labels
        description: |
          A list of labels for a labeled metric.  If provided, the labels are
          enforced at run time, and recording to an unknown label is recorded
          to the special label `__other__`.  If not provided, the labels
          may be anything, but using too many unique labels will put some
          labels in the special label `__other__`.

          Valid with any of the labeled metric types.
        anyOf:
          - type: array
            uniqueItems: true
            items:
              $ref: "#/definitions/labeled_metric_id"
            maxItems: 16
          - type: "null"

      extra_keys:
        title: Extra keys
        description: |
          The acceptable keys on the "extra" object sent with events. This is an
          object mapping the key to an object containing metadata about the key.
          A maximum of 10 extra keys is allowed.
          This metadata object has the following keys:

            - `description`: **Required.** A description of the key.

          Valid when `type`_ is `event`.
        type: object
        propertyNames:
          $ref: "#/definitions/dotted_snake_case"
        additionalProperties:
          type: object
          properties:
            description:
              type: string
          required:
            - description
        maxProperties: 10
        default: {}

      gecko_datapoint:
        title: Gecko Datapoint
        description: |
          This is a Gecko-specific property. It is the name of the Gecko metric
          to accumulate the data from, when using the Glean SDK in a product
          using GeckoView. See bug 1566356 for more context.

        type: string

      range_min:
        title: Range minimum
        description: |
          The minimum value of a custom distribution.

          Valid when `type`_ is `custom_distribution`.
        type: number
        default: 1

      range_max:
        title: Range maximum
        description: |
          The maximum value of a custom distribution.

          Required when `type`_ is `custom_distribution`.
        type: number

      bucket_count:
        title: Bucket count
        description: |
          The number of buckets to include in a custom distribution.

          Required when `type`_ is `custom_distribution`.
        type: number
        minimum: 1
        maximum: 100

      histogram_type:
        title: Histogram type
        description: |
          The type of histogram bucketing to use:
            - `linear`: The buckets are linearly spaced within the range.
            - `exponential`: The buckets use the natural logarithmic so the
              smaller-valued buckets are smaller in size than the higher-valued
              buckets.

          Required when `type`_ is `custom_distribution`.
        enum:
          - linear
          - exponential

      unit:
        title: Unit
        description: |
          The unit of the metric, for metrics that don't already require a
          meaningful unit, such as `time_unit`.
          This is provided for informational purposes only and doesn't have any
          effect on data collection.
        type: string

      no_lint:
        title: Lint checks to skip
        description: |
          This parameter lists any lint checks to skip for this metric only.
        type: array
        items:
          type: string

      decrypted_name:
        title: Decrypted name
        description: |
          Name of the column where to persist the decrypted value
          stored in the JWE after processing.

          Required when `type`_ is `jwe`.
        type: string
        pattern: "^[a-z_][a-z0-9_]{0,29}(\\.[a-z_][a-z0-9_]{0,29})*$"

      data_sensitivity:
        title: The level of data sensitivity
        description: |
          There are four data collection categories related to data sensitivity
          [defined here](https://wiki.mozilla.org/Firefox/Data_Collection):

          - **Category 1: Technical Data:** (`technical`) Information about the
            machine or Firefox itself. Examples include OS, available memory,
            crashes and errors, outcome of automated processes like updates,
            safebrowsing, activation, version \#s, and buildid. This also
            includes compatibility information about features and APIs used by
            websites, addons, and other 3rd-party software that interact with
            Firefox during usage.

          - **Category 2: Interaction Data:** (`interaction`) Information about
            the user’s direct engagement with Firefox. Examples include how many
            tabs, addons, or windows a user has open; uses of specific Firefox
            features; session length, scrolls and clicks; and the status of
            discrete user preferences.

          - **Category 3: Web activity data:** (`web_activity`) Information
            about user web browsing that could be considered sensitive. Examples
            include users’ specific web browsing history; general information
            about their web browsing history (such as TLDs or categories of
            webpages visited over time); and potentially certain types of
            interaction data about specific webpages visited.

          - **Category 4: Highly sensitive data:** (`highly_sensitive`)
            Information that directly identifies a person, or if combined with
            other data could identify a person. Examples include e-mail,
            usernames, identifiers such as google ad id, apple id, fxaccount,
            city or country (unless small ones are explicitly filtered out), or
            certain cookies. It may be embedded within specific website content,
            such as memory contents, dumps, captures of screen data, or DOM
            data.
        type: array
        items:
          enum:
            - technical
            - interaction
            - web_activity
            - highly_sensitive
          type: string
        minLength: 1
        uniqueItems: true

    required:
      - type
      - bugs
      - description
      - notification_emails
      - data_reviews
      - expires

type: object

propertyNames:
  anyOf:
    - allOf:
        - $ref: "#/definitions/dotted_snake_case"
        - not:
            description: "'pings' is reserved as a category name."
            const: pings
    - enum: ['$schema']

properties:
  $schema:
    type: string
    format: url

  no_lint:
    title: Lint checks to skip globally
    description: |
      This parameter lists any lint checks to skip for this whole file.
    type: array
    items:
      type: string

additionalProperties:
  type: object
  propertyNames:
    anyOf:
      - $ref: "#/definitions/short_id"
  additionalProperties:
    allOf:
      - $ref: "#/definitions/metric"
      -
        if:
          properties:
            type:
              const: event
        then:
          properties:
            lifetime:
              description: |
                Event metrics must have ping lifetime.
              const: ping
      - if:
          not:
            properties:
              type:
                enum:
                  - timing_distribution
                  - custom_distribution
                  - memory_distribution
                  - quantity
                  - boolean
                  - string
                  - labeled_counter
        then:
          properties:
            gecko_datapoint:
              description: |
                `gecko_datapoint` is only allowed for `timing_distribution`,
                `custom_distribution`, `memory_distribution`, `quantity`,
                `boolean`, `string` and `labeled_counter`.
              maxLength: 0
      -
        if:
          properties:
            type:
              enum:
                - custom_distribution
        then:
          required:
            - gecko_datapoint
          description: |
            `custom_distribution` is only allowed for Gecko
            metrics.
      -
        if:
          properties:
            type:
              const: custom_distribution
        then:
          required:
            - range_max
            - bucket_count
            - histogram_type
          description: |
            `custom_distribution` is missing required parameters `range_max`,
            `bucket_count` and `histogram_type`.
      -
        if:
          properties:
            type:
              const: memory_distribution
        then:
          required:
            - memory_unit
          description: |
            `memory_distribution` is missing required parameter `memory_unit`.
      -
        if:
          properties:
            type:
              const: quantity
        then:
          required:
            - unit
          description: |
            `quantity` is missing required parameter `unit`.
      -
        if:
          properties:
            type:
              const: jwe
        then:
          required:
            - decrypted_name
          description: |
            `jwe` is missing required parameter `decrypted_name`.