Steganography at scale: Embedding share URLs in Datadog widget screenshots (opens in new tab)

Datadog developed invisible pixel-level watermarks so screenshots can retain the context normally preserved by share links. The system embeds a compact widget snapshot ID into a widget’s border, while the full metadata remains in a Redis cache. This approach preserves screenshots’ convenience while enabling recovery of queries, time ranges, settings, and deep links at Datadog’s scale.

Share Links Versus Screenshots

• Copying a Datadog widget creates a backend record and places a unique share URL in the clipboard.
• Pasting the URL into a dashboard or notebook restores the widget.
• Slack and Teams integrations can render a live preview and link to Graph Explorer.
• Screenshots are easier to use and provide a consistent visual snapshot, but normally lose:
  • Time range
  • Underlying queries
  • Visualization type
  • Dashboard state
  • Configuration and context

Encoding Only a Snapshot ID

• A complete widget definition averages about 2 kB and may include queries, display settings, legends, time-frame overrides, template variables, dimensions, and deep links.
• Rather than embedding all of that data in the image, Datadog stores it in Redis and embeds only a randomly generated key.
• The frontend generates the snapshot ID optimistically before the cache write completes, allowing watermarking without waiting for a backend response.
• Records are retained for one hour because screenshots are usually shared within seconds or minutes.
• At more than 1 billion widget renders per day, IDs must be compact while avoiding cross-customer collisions.
• Datadog prefixes the cache key with the organization ID. An 8-byte ID provides roughly 2⁶⁴ possible values, producing an estimated collision probability of about 1 in 37 million under the stated usage assumptions.

Watermarking the Widget Border

• Every dashboard widget has a consistent 1-pixel border, making it a reliable location for encoding data regardless of visualization type.
• An initial design represented each bit with a separate colored pixel, but 64 pixels were needed for 8 bytes and could become visible.
• The final design stores data in RGB color adjustments:
  • Each pixel encodes up to 9 bits by offsetting the red, green, and blue channels.
  • The base color is calculated by subtracting 3 from each channel.
  • Channel offsets of up to 7 represent the encoded values.
• Two sentinel pixels, using a +7/+7/+7 offset, mark the beginning and end of the watermark.
• Eight pixels between the sentinels encode one byte each:
  • 3 bits in red
  • 3 bits in green
  • 2 highest bits in blue

Design Constraints

• The watermark must remain nearly invisible and avoid adding interface elements.
• It must work across different widget sizes, color profiles, display densities, and copy-paste workflows.
• The border-based method avoids visualization-specific implementations while keeping the encoded region short.

Datadog’s approach combines cached metadata with subtle RGB-level encoding, allowing screenshots to function like context-preserving share links without changing their appearance or the user’s workflow.