{"id":358371,"date":"2022-11-23T06:48:59","date_gmt":"2022-11-23T06:48:59","guid":{"rendered":"https:\/\/webkul.com\/blog\/?p=358371"},"modified":"2022-11-23T06:49:06","modified_gmt":"2022-11-23T06:49:06","slug":"check-docker-image-efficiency-and-reduce-image-size","status":"publish","type":"post","link":"https:\/\/webkul.com\/blog\/check-docker-image-efficiency-and-reduce-image-size\/","title":{"rendered":"Check docker image efficiency and reduce image size"},"content":{"rendered":"\n

The major concept of docker is that it uses an isolated filesystem known as a docker image while all docker containers run as a layer on these images. Any change in container does not affect the docker image at all, unless the container commits to image and makes the changes permanent. As these commits increase, the docker image size also increases exponentially. We will discuss here how to check docker image efficiency and reduce image size for better performance and save space as well.<\/p>\n\n\n\n

The reason behind the image size increasing exponentially on each commit is that the docker image keeps track of the changes in each commit i.e. layer. For example, if you change permissions for files in container and commit to image, the layer will have both files to keep track of the changes. This results in heavy size of the image. In this case, the best way to reduce image size is to remove these unnecessary files history from image commits by merging all commits into one. Let’s discuss how to do this:<\/p>\n\n\n\n

Check image efficiency<\/h2>\n\n\n\n

First of all we need to check the image efficiency and how much space we can save. There is a way to check potential space to save in an image, as well as check each layer content. We will use wagoodman\/dive<\/a> docker image for this purpose. Open terminal and run this command:<\/p>\n\n\n\n

docker run --rm -it -v \/var\/run\/docker.sock:\/var\/run\/docker.sock wagoodman\/dive:latest {your_image_id}<\/pre>\n\n\n\n
This command will take sometime according to image size. After the given image is loaded in this container, it will display image details and layers like this:<\/p>\n\n\n\n
 <\/p>\n\n\n\n
\"image-140\"<\/figure>\n\n\n\n
As you can see there is a possibility to save 377 MB in this image. You can also navigate through each layer and check changes in each layer of this image.<\/p>\n\n\n\n
Reduce image size<\/h2>\n\n\n\n
By performing last step, we know that the image has multiple layers and we can save some space by merging these layers. We can do this by docker export<\/a>\/import<\/a> commands. These commands already merge all commits into single layer. We need to perform 3 steps to reduce image size:<\/p>\n\n\n\n