From fa5e8c3d5c2496303e2c2488a765b826e427caed Mon Sep 17 00:00:00 2001 From: Yuqian Yang Date: Tue, 1 Nov 2016 18:48:25 +0800 Subject: [PATCH] Explain downloaded image and container sizes Signed-off-by: Yuqian Yang --- engine/tutorials/dockerimages.md | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/engine/tutorials/dockerimages.md b/engine/tutorials/dockerimages.md index 06713dfe47..e4b65dd4a1 100644 --- a/engine/tutorials/dockerimages.md +++ b/engine/tutorials/dockerimages.md @@ -568,6 +568,33 @@ Delete the `training/sinatra` image as you don't need it anymore. > **Note:** To remove an image from the host, please make sure > that there are no containers actively based on it. +## Check sizes of images and containers + +An image is +[stored in layers](../userguide/storagedriver/imagesandcontainers.md), +and shared with other images, the real disk usage depends on existing layers +on your host. A container is running on +[a writable layer](../userguide/storagedriver/imagesandcontainers.md#/container-and-layers) +on top of a readonly rootfs. + +You can figure the size of image layers with `docker history` command. + + $ docker history centos:centos7 + + IMAGE CREATED CREATED BY SIZE + 970633036444 6 weeks ago /bin/sh -c #(nop) CMD ["/bin/bash"] 0 B + 6 weeks ago /bin/sh -c #(nop) LABEL name=CentOS Base Imag 0 B + 6 weeks ago /bin/sh -c #(nop) ADD file:44ef4e10b27d8c464a 196.7 MB + 10 weeks ago /bin/sh -c #(nop) MAINTAINER https://github.c 0 B + +Also, you can check the sizes of containers by performing `docker ps` command with `-s`. + + $ docker ps -s + + CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES SIZE + cb7827c19ef7 docker-docs:is-11160-explain-image-container-size-prediction "hugo server --port=8" About a minute ago Up About a minute 0.0.0.0:8000->8000/tcp evil_hodgkin 0 B (virtual 949.2 MB) + + # Next steps Until now you've seen how to build individual applications inside Docker