Section 8 3 min read

Web images

A web image is a screenshot of the monitored page, captured from a monitoring region. Images are supporting evidence only: they never affect checks or the decision that a site is down.

Capture settings

Set these in the Web image capture section of a monitor's form:

  • Enable web image capture. Off by default.
  • Capture policy. Never, Every check, Periodic, Failures only, Incidents only, or Incidents and periodic (the default).
  • Periodic interval (minutes). 1 to 1440, default 30.
  • Capture on check failure, Capture when an incident is confirmed and Capture on recovery. All on by default. A capture happens only when both the box and the Capture policy allow it. Failure images need Failures only, Incidents only or Incidents and periodic. Images when an incident is confirmed and on recovery need Incidents only or Incidents and periodic. Unticking a box turns that capture off whatever the policy. At present, periodic images are taken at the Periodic interval whenever web image capture is enabled, whatever the policy. To stop them, untick Enable web image capture.
  • Capture full page (not just the viewport). Off by default.
  • Viewport width (px) 320 to 1920, default 1440, and Viewport height (px) 240 to 1200, default 900.
  • Format. WEBP, PNG or JPEG. Quality 1 to 100, default 82.
  • Retention (days, optional). 1 to 365. Left blank, images are kept for a standard period that depends on why they were taken: 7 days for periodic and on-demand images, 30 days for images of a failed check, and 90 days for images taken while an incident is verified, confirmed or resolved. These periods are the same on every plan. Expired images are removed once a day.
  • Wait strategy. When to take the picture: Network idle (the default), Load or DOM content loaded.
  • Capture timeout (seconds). 1 to 60, default 20.

The storage available for images depends on your plan and any Storage Pods you add, and is shown on the Mage Watcher service page in your Press Mage portal. When the storage is full, new images are not saved, and Mage Watcher shows no message about it: the images you already have stay, and no new ones appear. Capture now may still say Screenshot requested. New images are saved again once older ones pass their retention period and are removed, or once you add storage. Checks and alerts are never affected.

Taking an image now

Capture now on the monitor page or the Web images page, or the camera button on a monitor card, requests a one-off image. It works only when capture is switched on for that monitor; otherwise you see The screenshot could not be scheduled right now. The message Screenshot requested confirms it, and the image appears once a monitoring region has taken it. You can do this a few times a minute.

Viewing images

View all opens the monitor's Web images page: every image with its reason, region and time, a Filter by reason dropdown and Capture now. Click an image to open it full size with its details:

  • Captured at (UTC), Reason and Region.
  • Monitored URL, and the Final URL if the page redirected.
  • Dimensions, Format, Size and the Browser used.
  • Incident, a link to the incident the image belongs to, if any.
  • Integrity (SHA-256), a fingerprint that shows the image has not been altered.

Images taken around an incident also appear on the incident page under Visual evidence.

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