Question

How to deploy a new digest with the same tag to an app platform component

Posted on November 2, 2023
DigitalOcean App Platform
Asked by David Hackett

Hi there,

We’re using a third party image from docker hub for the source of one of our app platform components.

The third party releases bug fixes using the same tag, as in the 7.0 tag has recently been updated with version 7.0.9 with a new image and digest. Overwriting the old 7.0.8 version. The problem seems to be that whenever we update the app platform component it continues using the same version from when the component was first created.

So while our staging and production environments are both pointing to the same 7.0 tag, they’re actually running different versions of the container as staging was created long before production. Our staging component is running 7.0.2 while production is on 7.0.8.

I’ve tried forcing an update to use the most recent digest for the tag by updating the source tag to a different tag and back to 7.0 again as well as updating env vars to trigger a redeploy of the component. Each method failed as it seems like digital ocean has cached the old digest for that tag for the component meaning that each time we go back to 7.0 it carries on using the old version and doesn’t pull down the most recent digest for that tag.

What I was wondering about is if there is a way to clear the reference to the old digest for the component so when we redeploy the component it pulls down the most update to that tag please?

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Bobby Iliev

Site Moderator

• November 2, 2023

Accepted Answer

Hi there,

Indeed, overwriting tags when using Docker images can cause problems, as you have experienced.

Once an image with a specific tag is pulled and cached, subsequent pulls may not retrieve the latest version of that tag unless the cache is cleared or forced to update.

Best practices are to avoid overwriting tags, especially in production environments, and to use unique tags for each release, even incremental ones. That way, you can avoid confusion and unexpected behaviors.

However, in your current situation, you can try the following:

Instead of using tags like image:7.0, use the digest directly, for example image@sha256:<digest>.
Before switching back to the 7.0 tag, use a distinctly different tag temporarily, deploy your application, and then switch back to 7.0. This may force the platform to refresh the image from the repository.
Sometimes caches may be the cause, and you may need DigitalOcean’s support team to help you force an image refresh.