Bring Your Own Dockerfile
Full control over your runtime — no auto-detected language container
Auto-Rebuild on Push
Link a GitHub repo so every push rebuilds your image
Custom Docker Images require a Core plan or higher.
What Is a Custom Docker Image
For most apps, the supported languages auto-detect your project and run it in a production-hardened container for you. A Custom Docker Image is the alternative for when you need full control: you upload a build context — a.zip containing a
Dockerfile at its root — and Shard Cloud builds it and pushes it to an internal image registry.
Unlike a normal app, a custom image has no language, version, entrypoint, or custom command
settings. Whatever your image’s own ENTRYPOINT/CMD runs is what runs — the image is the
complete definition of how your app starts.
Building an Image
1
Prepare your build context
Zip up your project with a
Dockerfile at the root of the archive.2
Upload
Upload the zip from the dashboard, along with a name for the image. The zip must be no larger
than 100MB.
3
Build
Shard Cloud stores the image immediately and kicks off the build in the background — builds
can take several minutes, so you don’t wait around for it.
Watching the Build
The image goes through a simple status lifecycle:
You can watch the build’s live output from the dashboard while it’s running, or review the log
from the last completed build afterward.
Rebuilding an Image
Uploading a new build context for an existing image triggers a fresh build in place — same size/type limits as creating one. The image keeps the same identity throughout its life, so anything referencing it (like an app deployed from it) doesn’t need to change. A rebuild is rejected if the image is already building, and an image can’t be deleted while a build is in progress either.Deploying an App From an Image
Once an image has built successfully, you can deploy it as an app directly from the dashboard — give it a name, RAM, and optional description/subdomain/environment variables. This is the same as creating a normal app, minus the file upload and minus language/version/entrypoint/custom command — those come from the image itself. Deploying multiple apps from the same image is fine; the dashboard shows every app currently running from a given image alongside it.Auto-Rebuild on GitHub Push
Just like Git integration for regular apps, you can link a GitHub repository to a custom image so every push triggers a fresh build automatically.1
Connect GitHub
Go to Config → Integrations in the dashboard and connect your GitHub account, if you
haven’t already.
2
Link the repository
From the image’s page in the dashboard, choose the repository to link. Shard Cloud registers a
push webhook on the repository for you.
3
Push
Every push to the linked repository starts a rebuild the same way a manual rebuild would —
same “does not auto-redeploy running apps” behavior applies.
Deleting an Image
Deleting an image removes it from the registry entirely. This is blocked while a build is in progress. Deleting an image also deletes every app currently deployed from it — there’s nothing left for those apps to run once the image is gone.Limits
Limits apply to how many images you can have at once, regardless of their build status.