Gold Workflows Documentation

BUG=skia:
NOTRY=true
DOCS_PREVIEW= https://skia.org/?cl=1276663003

Review URL: https://codereview.chromium.org/1276663003

site/dev/testing/skiagold.md

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+Skia Gold
+=========
+
+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 sheriff, 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">
+
+