feat(preprod): Add odiff server wrapper and Dockerfile binary install by NicoHinderling · Pull Request #109380 · getsentry/sentry

NicoHinderling · 2026-02-25T21:54:47Z

Summary

Add OdiffServer subprocess wrapper that communicates with odiff via JSON-over-stdin/stdout protocol
Add DiffResult dataclass for structured diff output
Install the odiff binary in the self-hosted Dockerfile (x64 + arm64, SHA256-verified)

Stack: 1/3 — next: image comparison library

joshuarli · 2026-02-25T22:11:48Z

self-hosted/Dockerfile

  && apt-get update \
  && apt-get install -y --no-install-recommends $buildDeps \
  && uv sync --frozen --quiet --no-install-project \
+  && case "$(dpkg --print-architecture)" in \


we should move this into its own layer as it's separate from uv.lock, otherwise we'll do this every time a python dep changes

pretty sure this is all possible with docker primitives + multistage (to handle the docker arch for multiplat builds) at this point too; let me just commit this for you

NicoHinderling · 2026-02-25T22:18:40Z

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

rbro112 · 2026-02-26T16:06:39Z

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

+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)


Why dataclass over pydantic?

#109150 (comment)

I don't have too strong of an opinion but I'd lean to convention over a perfect performance implementation. I haven't personally seen dataclass used in the codebase, but I widely see pydantic models used, so for ease of use/devs to reuse best practices I'd lean towards using the more widely used convention, but up to you

(i moved it to pydantic in this most recent iteration btw)

rbro112 · 2026-02-26T16:07:06Z

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

+            if process is None or process.stdin is None or process.stdout is None:
+                raise RuntimeError("odiff server failed to initialize")
+            self._request_id += 1
+            request: dict[str, object] = {


Might be a bit cleaner to have this be a type so we don't use untyped dicts

for this case, I think we can leave this request object as is

rbro112 · 2026-02-26T16:07:34Z

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

+        compare_path: str | Path,
+        output_path: str | Path,
+        **options: object,
+    ) -> dict[str, Any]:


Might be good to type the response with a simple model to we're not using untyped dicts

rbro112 · 2026-02-26T16:09:20Z

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

+    def __exit__(self, *args: object) -> None:
+        self.close()
+
+    def _read_json(self, line: bytes) -> dict[str, Any]:


We likely wouldn't need this if we just had a type for the response.

rbro112 · 2026-02-26T16:14:59Z

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

+                raise RuntimeError("odiff server timed out after 30s")
+            line = process.stdout.readline()
+            try:
+                response = self._read_json(line)


This would become something like response = OdiffResponse.model_validate(line) if we used a pydantic model: https://docs.pydantic.dev/latest/concepts/json/

gotcha, okay let me try that out

I kept parse_obj(json.loads(line)) rather than model_validate_json since Sentry pins pydantic to v1 (pydantic>=1.10.26,<2 in pyproject.toml). model_validate_json is v2-only and doesn't exist at runtime or in mypy's pydantic plugin unfortunately

rbro112 · 2026-02-26T17:12:34Z

package.json

    "jest-fail-on-console": "3.3.1",
    "jest-junit": "16.0.0",
    "knip": "5.83.1",
+    "odiff-bin": "^4.3.2",


Why do we need the package.json change? This is only touching backend

right, i removed it initially as you remember, but as it turns out, for local development, this is the easiest way to have access to odiff

rbro112 · 2026-02-26T17:12:59Z

knip.config.ts

    '@babel/preset-react', // Still used in jest
    '@babel/preset-typescript', // Still used in jest
    '@emotion/babel-plugin', // Still used in jest
+    'odiff-bin', // raw binary consumed by Python backend, not a JS import


Hmm, why is this needed in knip? That's only a frontend check IIUC

this is needed because odiff is used for dev purposes and knip freaks out that we have a package that doesnt seem to be referenced in the frontend code

rbro112 · 2026-02-26T18:42:00Z

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

+    def __exit__(self, *args: object) -> None:
+        self.close()
+
+    def _read_json(self, line: bytes) -> dict[str, object]:


I'd like to remove this entirely, it seems it's only used twice (_read_response and _start). _read_response is already typed and the json.loads should be fine to do inline. If it throws, that's a valid error we want to catch (and catching and rethrowing anyways?)

In _start I feel we should just inline json.loads(). Both errors here are just rethrown, so I don't see what catching and rethrowing is doing in this function

tried to incorporate this feedback. Removed _read_json entirely and inlined json.loads at both call sites. Kept parse_obj over model_validate_json since we pin pydantic to v1.

Add the odiff subprocess wrapper (OdiffServer) for image comparison, the DiffResult type, and install the odiff binary in the self-hosted Dockerfile.

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

…109381) ## Summary - Add `compare_images` and `compare_images_batch` functions using dual-threshold detection (base + color-sensitive) - Produces base64-encoded diff mask PNGs with pixel-level change data - Unit tests covering identical, different, different-size, threshold sensitivity, bytes input, and batch modes **Stack**: 2/3 — depends on #109380, next: Celery task --------- Co-authored-by: Claude <noreply@anthropic.com>

NicoHinderling requested review from a team as code owners February 25, 2026 21:54

NicoHinderling mentioned this pull request Feb 25, 2026

feat(preprod): Add image comparison library with odiff batch support #109381

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This was referenced Feb 25, 2026

feat(preprod): Add snapshot image comparison task and endpoint logic #109151

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feat(preprod): Add snapshot comparison task #109382

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

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hodl #109397

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feat(preprod): wip web stuff #109403

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NicoHinderling added 12 commits February 26, 2026 10:51

feat(preprod): Add odiff server wrapper and Dockerfile binary install

06bdc3c

Add the odiff subprocess wrapper (OdiffServer) for image comparison, the DiffResult type, and install the odiff binary in the self-hosted Dockerfile.

fixes

974e048

bugbot

420a881

small code simplification

fa25780

more

3ca7a23

avoid deadlock

6f8e0b1

finding odiff

50bcd46

get odiff to still work locally via pnpm

a87b6ab

include knip alowlist

9d76e77

robot

8c386f8

try switching to pydantic

ccf5df7

rbro json loads comment

4b62d3f

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NicoHinderling merged commit afeb841 into master Feb 26, 2026
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NicoHinderling deleted the create-compare-task-v1-part1 branch February 26, 2026 19:26

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