---
title: 'Skia Gold'
linkTitle: 'Skia Gold'
---

## Overview

Gold is a web application that compares the images produced by our bots against
known baseline images.

Key features:

- Baselines are managed in Gold outside of Git, but in lockstep with Git
  commits.
- Each commit creates >500k images.
- Deviations from the baseline are triaged after a CL lands and images are
  triaged as either `positive` or `negative`. 'Positive' means the diff is
  considered acceptable. 'Negative' means the diff is considered unacceptable
  and requires a fix. If a CL causes Skia to break it is reverted or an
  additional CL is landed to fix the problem.
- We test across a range of dimensions, e.g.:

  - OS (Windows, Linux, Mac, Android, iOS)
  - Architectures (Intel, ARM)
  - Backends (CPU, OpenGL, Vulkan etc.)
  - etc.

- Written in Go, Polymer and deployed on the Google Cloud. The code is in the
  [Skia Infra Repository](https://github.com/google/skia-buildbot).

## Recommended Workflows

### How to best use Gold for commonly faced problems

These instructions will refer to various views which are accessible via the left
navigation on [gold.skia.org](https://gold.skia.org/).

View access is public, triage access is granted to Skia contributors. You must
be logged in to triage.

## Problem #1: As Skia Gardener, I need to triage and “assign” many incoming new images.

Solution today:

- Access the By Blame view to see digests needing triage and associated
  owners/CLs
  - Only untriaged digests will be shown by default
  - Blame is not sorted in any particular order
  - Digests are clustered by runs and the most minimal set of blame

<img src=../BlameView.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

- Select digests for triage
  - Digests will be listed in order with largest difference first
  - Click to open the digest view with detailed information

<img src=../Digests.png style="margin-left:40px" align="left" width="780"/>
<br clear="left">

- Open bugs for identified owner(s)
  - The digest detail view has a link to open a bug from the UI
  - Via the Gold UI or when manually entering a bug, copy the full URL of single
    digest into a bug report
  - The URL reference to the digest in Issue Tracker will link the bug to the
    digest in Gold

<img src="../IssueHighlight.png" style="margin-left:60px" align="left" width="720" border=1/>
<br clear="left">

<br>

Future improvements:

- Smarter, more granular blamelist

<br>

## Problem #2: As a developer, I need to land a CL that may change many images.

To find your results:

- Immediately following commit, access the By Blame view to find untriaged
  digest groupings associated with your ID
- Click on one of the clusters including your CL to triage
- Return to the By Blame view to walk through all untriaged digests involving
  your change
- Note: It is not yet implemented in the UI but possible to filter the view by
  CL. Delete hashes in the URL to only include the hash for your CL.

<img src=../BlameView.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

To rebaseline images:

- Access the Ignores view and create a new, short-interval (hours) ignore for
  the most affected configuration(s)

<img src=../Ignores.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

- Click on the Ignore to bring up a search view filtered by the affected
  configuration(s)
- Mark untriaged images as positive (or negative if appropriate)
- Follow one of two options for handling former positives:
  - Leave former positives as-is and let them fall off with time if there is low
    risk of recurrence
  - Mark former positives as negative if needed to verify the change moving
    forward

Future improvements:

- Trybot support prior to commit, with view limited to your CL
- Pre-triage prior to commit that will persist when the CL lands

<br>

## Problem #3: As a developer or infrastructure engineer, I need to add a new or updated config.

(ie: new bot, test mode, environment change)

Solution today:

- Follow the process for rebaselining images:
  - Wait for the bot/test/config to be committed and show up in the Gold UI
  - Access the Ignores view and create a short-interval ignore for the
    configuration(s)
  - Triage the ignores for that config to identify positive images
  - Delete the ignore

Future improvements:

- Introduction of a new or updated test can make use of try jobs and pre-triage.
- New configs may be able to use these features as well.

<br>

## Problem #4: As a developer, I need to analyze the details of a particular image digest.

Solution:

- Access the By Test view

<img src=../ByTest.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

- Click the magnifier to filter by configuration
- Access the Cluster view to see the distribution of digest results
  - Use control-click to select and do a direct compare between data points
  - Click on configurations under “parameters” to highlight data points and
    compare

<img src=../ClusterConfig.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

- Access the Grid view to see NxN diffs

<img src=../Grid.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

- Access the Dot diagram to see history of commits for the trace
  - Each dot represents a commit
  - Each line represents a configuration
  - Dot colors distinguish between digests

<img src=../DotDiagram.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">

<br>

Future improvements:

- Large diff display of image vs image

<br>

## Problem #5: As a developer, I need to find results for a particular configuration.

Solution:

- Access the Search view
- Select any parameters desired to search across tests

<img src=../Search.png style="margin-left:30px" align="left" width="800"/>
<br clear="left">