docker clear up for mac

清理mac上Docker占用的磁盘空间

1.1、内容：

Docker依赖Linux系统的cgroup实现，  在mac系统中运行的时候，Docker会启动一个虚拟机中的Linux内核，并在 硬盘上放一个 qcow2 格式的磁盘镜像文件。这个 文件会随着Docker的使用不断  膨胀， 即使删除不用的Docker Image和 Container也不会缩小。我在 测试完一个自动 化工具的Dockerfile改写之后，Docker.qcow2文件就达到42GB了。

Google搜了一圏发现一个叫Théo Chamley 的法国人写了一个脚本释放Docker.qcow2文件占用的空间。基本原理是用 docker save 命令保存要保留的image，然后关闭Docker，删除 Docker.qcow2 ，再启动Docker，它会自动重建，最后用 docker load 命令恢复保留的image。

命令行

 sudo sh docker-clean.sh $(docker images | awk 'NR>1 {print $1":"$2}')

脚本

#!/bin/bash
# sudo sh docker-clean.sh $(docker images | awk 'NR>1 {print $1":"$2}')

IMAGES=$@

echo "This will remove all your current containers and images except for:"
echo ${IMAGES}
read -p "Are you sure? [yes/NO] " -n 1 -r
echo    # (optional) move to a new line
if [[ ! $REPLY =~ ^[Yy]$ ]]
then
    exit 1
fi


TMP_DIR=$(mktemp -d)

pushd $TMP_DIR >/dev/null

open -a Docker
echo "=> Saving the specified images"
for image in ${IMAGES}; do
	echo "==> Saving ${image}"
	tar=$(echo -n ${image} | base64)
	docker save -o ${tar}.tar ${image}
	echo "==> Done."
done

echo "=> Cleaning up"
echo -n "==> Quiting Docker"
osascript -e 'quit app "Docker"'
while docker info >/dev/null 2>&1; do
	echo -n "."
	sleep 1
done;
echo ""

echo "==> Removing Docker.qcow2 file"
rm ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/Docker.qcow2

echo "==> Launching Docker"
open -a Docker
echo -n "==> Waiting for Docker to start"
until docker info >/dev/null 2>&1; do
	echo -n "."
	sleep 1
done;
echo ""

echo "=> Done."

echo "=> Loading saved images"
for image in ${IMAGES}; do
	echo "==> Loading ${image}"
	tar=$(echo -n ${image} | base64)
	docker load -q -i ${tar}.tar || exit 1
	echo "==> Done."
done

popd >/dev/null
rm -r ${TMP_DIR}

貌似更好

This patch fixes a bug which would prevent the online compaction from being enabled. Hopefully now it's possible to turn it on again. I installed this version and then enabled experimental compaction by running the following script:

#!/bin/bash

cd ~/Library/Containers/com.docker.docker/Data/database/
git checkout master
git reset --hard
mkdir -p com.docker.driver.amd64-linux/disk
echo 262144 > com.docker.driver.amd64-linux/disk/compact-after
echo 262144 > com.docker.driver.amd64-linux/disk/keep-erased
echo -n true > com.docker.driver.amd64-linux/disk/trim
#echo -n 'tcp:9090' > com.docker.driver.amd64-linux/disk/stats
git add com.docker.driver.amd64-linux/disk/compact-after
git add com.docker.driver.amd64-linux/disk/keep-erased
git add com.docker.driver.amd64-linux/disk/trim
#git add com.docker.driver.amd64-linux/disk/stats
git commit -s -m 'Enable on-line compaction'

I then rebooted the app. I created a large temporary file in a container, deleted it, and around 15 minutes later an fstrim /var was triggered from cron and the file became smaller again. (It's also possible to trigger fstrim immediately with a command like docker run --rm --net=host --pid=host --privileged -it justincormack/nsenter1 /sbin/fstrim /var)

In 17.07 (the upcoming edge release) I'm hoping to switch online compaction on by default. In 17.08 I'm hoping to automatically trigger fstrim when docker images are removed, instead of waiting for a cron job.