feat(preprod): Add snapshot image comparison task and endpoint logic by NicoHinderling · Pull Request #109151 · getsentry/sentry

NicoHinderling · 2026-02-23T23:08:24Z

Adds the ability to automatically compare snapshot images between two preprod builds using pixel-level diffing.

When a snapshot is uploaded with VCS info (base_sha, base_repo_name, base_ref), the endpoint now looks for a matching base artifact and triggers a compare_snapshots Celery task. This task:

Fetches manifests for both head and base artifacts
Matches images by file name across the two builds
Runs pixel-level comparison using odiff (via a new image_diff module)
Stores diff masks and a comparison manifest in object storage
Records results in a PreprodSnapshotComparison model

The GET endpoint is updated to return categorized image lists (changed, added, removed, unchanged) along with diff metadata when comparison data is available.

New modules:

sentry.preprod.snapshots.image_diff — wraps the odiff binary in server mode for efficient batch image comparison
sentry.preprod.snapshots.tasks — Celery task for async snapshot comparison
snapshot-diff internal endpoint registered in URL patterns

Also adds odiff-bin as a dependency for the image diffing binary.

github-actions · 2026-02-23T23:08:43Z

🚨 Warning: This pull request contains Frontend and Backend changes!

It's discouraged to make changes to Sentry's Frontend and Backend in a single pull request. The Frontend and Backend are not atomically deployed. If the changes are interdependent of each other, they must be separated into two pull requests and be made forward or backwards compatible, such that the Backend or Frontend can be safely deployed independently.

Have questions? Please ask in the #discuss-dev-infra channel.

src/sentry/preprod/snapshots/image_diff/odiff.py

src/sentry/preprod/snapshots/tasks.py

NicoHinderling · 2026-02-24T00:56:26Z

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feat(preprod): Add snapshot image comparison task and endpoint logic #109151 : 2 dependent PRs (#109397 , #109403 ) 👈 (View in Graphite)
feat(preprod): Add snapshot comparison Celery task #109382
feat(preprod): Add image comparison library with odiff batch support #109381
feat(preprod): Add odiff server wrapper and Dockerfile binary install #109380
master

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src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py

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src/sentry/preprod/snapshots/tasks.py

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src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py

sentry · 2026-02-26T05:29:58Z

src/sentry/preprod/snapshots/tasks.py


                    safe_name = name.replace("\\", "/").strip("/")
-                    stem = safe_name.rsplit(".", 1)[0] if "." in safe_name else safe_name
+                    diff_path = safe_name.removesuffix(".png") + ".png"


Bug: The use of removesuffix(".png") incorrectly handles non-PNG image files, leading to malformed file paths for diff masks like image.jpg.png.
_{Severity: HIGH}

Suggested Fix

Revert to the previous, more robust implementation of stripping the file extension, such as using safe_name.rsplit(".", 1)[0], to correctly handle any image file extension before appending .png.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: src/sentry/preprod/snapshots/tasks.py#L340 Potential issue: The logic for generating the diff mask path was changed from `safe_name.rsplit(".", 1)[0]` to `safe_name.removesuffix(".png")`. This new implementation only handles files with a `.png` extension. Since the file upload process does not validate or enforce a specific image format, a user can upload images with other extensions like `.jpg` or `.jpeg`. In such cases, the new code will generate an incorrect path, such as `image.jpg.png` instead of `image.png`. This causes the diff mask to be stored with an incorrect key in object storage, and the path returned to the frontend will be broken, making the diff image inaccessible.

@rbro112 perhaps we can do non PNGs as a follow up task

https://linear.app/getsentry/issue/EME-892/add-support-for-non-png-snapshot-images

worth a discussion

sentry · 2026-02-26T06:48:04Z

src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py

+            result = response.dict()
+            result["org_id"] = str(project.organization_id)
+            result["project_id"] = str(project.id)
+            result["comparison_type"] = comparison_type
+            if comparison_state is not None:
+                result["comparison_state"] = comparison_state
+
+            return result

        return self.paginate(
            request=request,


Bug: The endpoint returns a paginated images list but includes unpaginated changed, added, and removed lists, leading to an inconsistent API response.
_{Severity: MEDIUM}

Suggested Fix

Filter the changed, added, removed, and unchanged lists within the on_results callback to only include items that are present in the paginated images list. This will ensure all data in the response is consistent with the current page.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py#L309-L337 Potential issue: In the `PreprodArtifactSnapshotEndpoint`, the pagination logic incorrectly combines paginated and unpaginated data. The `self.paginate` method correctly slices the `image_list` to create a paginated list of `images` for the current page. However, the `on_results` callback, which receives this paginated list, constructs the final API response using the full, unpaginated `changed`, `added`, `removed`, and `unchanged` lists. These lists are calculated from the complete dataset before pagination is applied. This results in an inconsistent API response where the `images` field is paginated, but the change-categorized lists contain all items, not just those relevant to the current page.

ignore for now

sentry · 2026-02-26T07:04:09Z

src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py

+                            SnapshotImageResponse(
+                                key=img_data.get("base_hash", ""),
+                                display_name=name,
+                                image_file_name=name,
+                                width=img_data.get("before_width", 0),
+                                height=img_data.get("before_height", 0),
+                            )
+                        )
+                elif status == "unchanged":
+                    if head_img:
+                        unchanged.append(head_img)


Bug: The snapshot comparison endpoint silently ignores images with "errored" or "skipped" statuses, returning partial results without any indication of data loss to the user.
_{Severity: MEDIUM}

Suggested Fix

Update the API response model and database model to track counts for errored and skipped images. The GET endpoint should populate these fields from the comparison manifest and return them to the frontend. This will ensure the user is aware when a comparison is incomplete.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: src/sentry/preprod/api/endpoints/preprod_artifact_snapshot.py#L241-L283 Potential issue: The snapshot comparison task can generate images with `"errored"` or `"skipped"` statuses, for example, when an image fails to process or exceeds a diff limit. However, the GET endpoint that serves these comparison results only handles `"changed"`, `"added"`, `"removed"`, and `"unchanged"` statuses. Images with `"errored"` or `"skipped"` statuses are silently ignored. This causes the API to return a success status with partial data, giving the user a false impression that the comparison was complete when data was actually lost.

I will consolidate these two cases into one and then handle showing them on the frontend in a later PR

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NicoHinderling closed this Feb 24, 2026

NicoHinderling reopened this Feb 24, 2026

NicoHinderling changed the base branch from master to graphite-base/109151 February 24, 2026 00:55

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feat(preprod): Add snapshot image comparison task with odiff #109150

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NicoHinderling added 5 commits February 25, 2026 23:07

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