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# Snowplow Guide
This guide provides an overview of how Snowplow works, and implementation details.
For more information about Product Intelligence, see:
- **Trackers** fire Snowplow events. Snowplow has 12 trackers, covering web, mobile, desktop, server, and IoT.
- **Collectors** receive Snowplow events from trackers. We have three different event collectors, synchronizing events either to Amazon S3, Apache Kafka, or Amazon Kinesis.
- **Enrich** cleans up the raw Snowplow events, enriches them and puts them into storage. We have an Hadoop-based enrichment process, and a Kinesis-based or Kafka-based process.
- **Storage** is where the Snowplow events live. We store the Snowplow events in a flat file structure on S3, and in the Redshift and PostgreSQL databases.
- **Data modeling** is where event-level data is joined with other data sets and aggregated into smaller data sets, and business logic is applied. This produces a clean set of tables which make it easier to perform analysis on the data. We have data models for Redshift and Looker.
- **Analytics** are performed on the Snowplow events or on the aggregate tables.
- The user level, though user tracking can be disabled on a per-user basis.
GitLab respects the [Do Not Track](https://www.eff.org/issues/do-not-track) standard, so any user who has enabled the Do Not Track option in their browser is not tracked at a user level.
Snowplow tracking is enabled on GitLab.com, and we use it for most of our tracking strategy.
To enable Snowplow tracking on a self-managed instance:
When adding new click events, we should add them in a way that's internally consistent. If we don't, it is difficult to perform analysis across features because each feature captures events differently.
The current method provides several attributes that are sent on each click event. Please try to follow these guidelines when specifying events to capture:
| attribute | type | required | description |
| --------- | ------- | -------- | ----------- |
| category | text | true | The page or backend area of the application. Unless infeasible, please use the Rails page attribute by default in the frontend, and namespace + class name on the backend. |
| action | text | true | The action the user is taking, or aspect that's being instrumented. The first word should always describe the action or aspect: clicks should be `click`, activations should be `activate`, creations should be `create`, etc. Use underscores to describe what was acted on; for example, activating a form field would be `activate_form_input`. An interface action like clicking on a dropdown would be `click_dropdown`, while a behavior like creating a project record from the backend would be `create_project` |
| label | text | false | The specific element or object to act on. This can be one of the following: the label of the element (for example, a tab labeled 'Create from template' for `create_from_template`), a unique identifier if no text is available (for example, `groups_dropdown_close` for closing the Groups dropdown in the top bar), or the name or title attribute of a record being created. |
| value | decimal | false | Describes a numeric value or something directly related to the event. This could be the value of an input. For example, `10` when clicking `internal` visibility. |
Snowplow JS adds many [web-specific parameters](https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/snowplow-tracker-protocol/#Web-specific_parameters) to all web events by default.
GitLab provides `Tracking`, an interface that wraps the [Snowplow JavaScript Tracker](https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/javascript-trackers/) for tracking custom events. The simplest way to use it is to add `data-` attributes to clickable elements and dropdowns. There is also a Vue mixin (exposing a `track` method), and the static method `Tracking.event`. Each of these requires at minimum a `category` and an `action`. You can provide additional [Structured event taxonomy](#structured-event-taxonomy) properties along with an `extra` object that accepts key-value pairs.
| `category` | string | `document.body.dataset.page` | Page or subsection of a page that events are being captured within. |
| `action` | string | generic | Action the user is taking. Clicks should be `click` and activations should be `activate`, so for example, focusing a form field would be `activate_form_input`, and clicking a button would be `click_button`. |
| `data` | object | `{}` | Additional data such as `label`, `property`, `value`, `context` (as described in our [Structured event taxonomy](#structured-event-taxonomy)), and `extra` (key-value pairs object). |
- Use [data attributes](#tracking-with-data-attributes) on HTML elements that emits either the `click`, `show.bs.dropdown`, or `hide.bs.dropdown` events.
- Use the [Vue mixin](#tracking-within-vue-components) when tracking custom events, or if the supported events for data attributes are not propagating.
- Use the [Tracking class directly](#tracking-in-raw-javascript) when tracking on raw JS files.
When working in HAML (or Vue templates) we can add `data-track-*` attributes to elements of interest. All elements that have a `data-track-action` attribute automatically have event tracking bound on clicks. You can provide extra data as a valid JSON string using `data-track-extra`.
Event listeners are bound at the document level to handle click events on or within elements with these data attributes. This allows them to be properly handled on re-rendering and changes to the DOM. Note that because of the way these events are bound, click events should not be stopped from propagating up the DOM tree. If click events are being stopped from propagating, you must implement your own listeners and follow the instructions in [Tracking within Vue components](#tracking-within-vue-components) or [Tracking in raw JavaScript](#tracking-in-raw-javascript).
| `data-track-action` | true | Action the user is taking. Clicks must be prepended with `click` and activations must be prepended with `activate`. For example, focusing a form field would be `activate_form_input` and clicking a button would be `click_button`. Replaces `data-track-event`, which was [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/290962) in GitLab 13.11. |
| `data-track-label` | false | The `label` as described in our [Structured event taxonomy](#structured-event-taxonomy). |
| `data-track-property` | false | The `property` as described in our [Structured event taxonomy](#structured-event-taxonomy). |
| `data-track-value` | false | The `value` as described in our [Structured event taxonomy](#structured-event-taxonomy). If omitted, this is the element's `value` property or `undefined`. For checkboxes, the default value is the element's checked attribute or `0` when unchecked. |
| `data-track-extra` | false | A key-value pairs object passed as a valid JSON string. This is added to the `extra` property in our [`gitlab_standard`](#gitlab_standard) schema. |
When using the GitLab helper method [`nav_link`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/helpers/tab_helper.rb#L76) be sure to wrap `html_options` under the `html_options` keyword argument.
Be careful, as this behavior can be confused with the `ActionView` helper method [`link_to`](https://api.rubyonrails.org/v5.2.3/classes/ActionView/Helpers/UrlHelper.html#method-i-link_to) that does not require additional wrapping of `html_options`
There's a tracking Vue mixin that can be used in components if more complex tracking is required. To use it, first import the `Tracking` library and request a mixin.
You can provide default options that are passed along whenever an event is tracked from within your component. For example, if all events in a component should be tracked with a given `label`, you can provide one at this time. Available defaults are `category`, `label`, `property`, and `value`. If no category is specified, `document.body.dataset.page` is used as the default.
You can then use the mixin normally in your component with the `mixin` Vue declaration. The mixin also provides the ability to specify tracking options in `data` or `computed`. These override any defaults and allow the values to be dynamic from props, or based on state.
Custom event tracking and instrumentation can be added by directly calling the `Tracking.event` static function. The following example demonstrates tracking a click on a button by calling `Tracking.event` manually.
Enable Snowplow automatic [form tracking](https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/javascript-trackers/javascript-tracker/javascript-tracker-v2/tracking-specific-events/#form-tracking) by calling `Tracking.enableFormTracking` (after the DOM is ready) and providing a `config` object that includes at least one of the following elements:
GitLab provides `Gitlab::Tracking`, an interface that wraps the [Snowplow Ruby Tracker](https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/ruby-tracker/) for tracking custom events.
Custom event tracking and instrumentation can be added by directly calling the `GitLab::Tracking.event` class method, which accepts the following arguments:
| `category` | String | | Area or aspect of the application. This could be `HealthCheckController` or `Lfs::FileTransformer` for instance. |
| `action` | String | | The action being taken, which can be anything from a controller action like `create` to something like an Active Record callback. |
| `label` | String | nil | As described in [Structured event taxonomy](#structured-event-taxonomy). |
| `property` | String | nil | As described in [Structured event taxonomy](#structured-event-taxonomy). |
| `value` | Numeric | nil | As described in [Structured event taxonomy](#structured-event-taxonomy). |
| `context` | Array\[SelfDescribingJSON\] | nil | An array of custom contexts to send with this event. Most events should not have any custom contexts. |
| `project` | Project | nil | The project associated with the event. |
| `user` | User | nil | The user associated with the event. |
| `namespace` | Namespace | nil | The namespace associated with the event. |
| `extra` | Hash | `{}` | Additional keyword arguments are collected into a hash and sent with the event. |
Tracking can be viewed as either tracking user behavior, or can be used for instrumentation to monitor and visualize performance over time in an area or aspect of code.
We use the [AsyncEmitter](https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/ruby-tracker/emitters/#the-asyncemitter-class) when tracking events, which allows for instrumentation calls to be run in a background thread. This is still an active area of development.
Snowplow Inspector Chrome Extension is a browser extension for testing frontend events. This works on production, staging and local development environments.
1. Open the Chrome extension by pressing the Snowplow Inspector icon beside the address bar.
1. Click around on a webpage with Snowplow and you should see JavaScript events firing in the inspector window.
### Snowplow Micro
Snowplow Micro is a very small version of a full Snowplow data collection pipeline: small enough that it can be launched by a test suite. Events can be recorded into Snowplow Micro just as they can a full Snowplow pipeline. Micro then exposes an API that can be queried.
Snowplow Micro is a Docker-based solution for testing frontend and backend events in a local development environment. You must modify GDK using the instructions below to set this up.
1. Install [Snowplow Micro](https://github.com/snowplow-incubator/snowplow-micro) by cloning the settings in [this project](https://gitlab.com/gitlab-org/snowplow-micro-configuration):
1. Navigate to the directory with the cloned project, and start the appropriate Docker
To control content security policy warnings when using an external host, you can allow or disallow them by modifying `config/gitlab.yml`. To allow them, add the relevant host for `connect_src`. For example, for `https://snowplow.trx.gitlab.net`:
We are including the [`gitlab_standard` schema](https://gitlab.com/gitlab-org/iglu/-/blob/master/public/schemas/com.gitlab/gitlab_standard/jsonschema/) with every event. See [Standardize Snowplow Schema](https://gitlab.com/groups/gitlab-org/-/epics/5218) for details.
The [`StandardContext`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/tracking/standard_context.rb) class represents this schema in the application.
| `plan` | **{dotted-circle}** | string (max 32 chars) | Name of the plan for the namespace, such as `free`, `premium`, or `ultimate`. Automatically picked from the `namespace`. |
| `network_userid` | **{dotted-circle}** | string | Unique identifier for a user, based on a cookie from the collector (so set at a network level and shouldn't be set by a tracker) |
| `os_family` | **{dotted-circle}** | string | Operating system family |
| `os_manufacturer` | **{dotted-circle}** | string | Manufacturers of operating system |
| `os_name` | **{dotted-circle}** | string | Name of operating system |