ARTIFACTORY: Why is the size of the Docker image in Artifactory smaller than the size displayed in the Docker client?

When comparing the size of the Docker image displayed in the JFrog Platform UI to the size displayed in the Docker client, you may notice that the size displayed in Artifactory is smaller than the size observed via the client.

Artifactory UI Docker image size:

 

Docker client image size:

 

Why is this happening?

As you may know, each Docker image consists of a series of layers, so when we push the image to Artifactory, each layer is compressed to a “.tar.gzip” mediaType.

To demonstrate this, you may use the JFrog Platform UI to navigate to the “manifest.json" file of the corresponding Docker image under your Docker repository, then click the “View” button to see the compressed layers:

 As seen in the above “manifest.json” file, the Docker image layers are compressed into a “.tar.gzip” mediaType (gzip is a file format and a software application used for file compression and decompression).
As a result, the compression process reduces the file sizes of the layers, and this is the reason we see the difference between the Artifactory UI and the size displayed via the Docker client.