# Hey everyone, I've set up S3 for Discourse, but why are topic browsing images using COS links?

**URL:** <https://meta.discourse.org/t/discourse-s3-cos/417219>\
**Category:** Self-hosting\
**Created:** [November 12, 2026, 2:54pm UTC](https://meta.discourse.org/t/discourse-s3-cos/417219 "2026-11-12T14:54:22Z")\
**Posts on this page:** 1\
**Showing post:** 1

<div class="post-metadata">

**Author:** ![danguaitu](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danguaitu](https://meta.discourse.org/u/danguaitu)\
**Post date:** [November 12, 2026, 2:54pm UTC](https://meta.discourse.org/t/discourse-s3-cos/417219/1 "2026-11-12T14:54:22Z")

</div>

Hey everyone, I’ve finished setting up S3 for Discourse. Why are the topic thumbnail images still going through the COS link? I’m using Tencent Cloud COS connected to EdgeOne.

```yaml
DISCOURSE_USE_S3: true
DISCOURSE_S3_REGION: ap-beijing
DISCOURSE_S3_ENDPOINT: https://cos.ap-beijing.myqcloud.com
DISCOURSE_S3_ACCESS_KEY_ID:
DISCOURSE_S3_SECRET_ACCESS_KEY:
DISCOURSE_S3_CDN_URL: https://\*\*\*\*\*\*\*/uploads/discourse
DISCOURSE_S3_BUCKET: \*\*\*\*\*\*\*\*\*\*\*/uploads/discourse
DISCOURSE_S3_BACKUP_BUCKET: \*\*\*\*\*\*\*\*\*\*\*/discourse
DISCOURSE_BACKUP_LOCATION: s3
DISCOURSE_S3_INSTALL_CORS_RULE: false
DISCOURSE_S3_USE_ACLS: false

  after_assets_precompile:

    - exec:

        cd: $home

        cmd:

          - sudo -E -u discourse bundle exec rake s3:upload_assets

          - sudo -E -u discourse bundle exec rake s3:expire_missing_assets

```

Since this is a fresh installation:

I rebuilt directly, and the CSS, JS, and images were all successfully uploaded to COS. The resources are also being accessed and cached via the domain bound to EdgeOne.

However, when I check the admin backend, the topic thumbnails are still using the COS link. What could be the reason? Does anyone know how to solve this?

---

_[View the full topic](https://meta.discourse.org/t/discourse-s3-cos/417219)._