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.