另一种方法是假设您的基本映像很快就会落后(这很可能发生)，并定期强制应用程序构建另一个映像(例如每周)，如果它发生了更改，则重新部署它。

据我所知，像官方Debian或Java这样的流行基础镜像会更新它们的标记来满足安全修复，所以标记不是不可变的(如果你想要更强的保证，你需要使用参考[image:@digest]，在最新的Docker版本中可用)。因此，如果你要用docker build -pull构建你的映像，那么你的应用程序应该得到你引用的base image标签的最新和最好的。

由于可变标记可能令人困惑，所以最好每次都增加应用程序的版本号，这样至少在您的方面，事情会更清楚。

因此，我不确定在前面的答案之一中建议的脚本是否能完成工作，因为它不重新构建应用程序的映像——它只是更新基本映像标记，然后重新启动容器，但新的容器仍然引用旧的基本映像散列。

我不提倡在容器中运行cron类型的作业(或任何其他进程，除非真的有必要)，因为这违背了每个容器只运行一个进程的原则(关于为什么这样更好有各种各样的争论，所以我不打算在这里讨论)。

You can use Watchtower to watch for updates to the image a container is instantiated from and automatically pull the update and restart the container using the updated image. However, that doesn't solve the problem of rebuilding your own custom images when there's a change to the upstream image it's based on. You could view this as a two-part problem: (1) knowing when an upstream image has been updated, and (2) doing the actual image rebuild. (1) can be solved fairly easily, but (2) depends a lot on your local build environment/practices, so it's probably much harder to create a generalized solution for that.

If you're able to use Docker Hub's automated builds, the whole problem can be solved relatively cleanly using the repository links feature, which lets you trigger a rebuild automatically when a linked repository (probably an upstream one) is updated. You can also configure a webhook to notify you when an automated build occurs. If you want an email or SMS notification, you could connect the webhook to IFTTT Maker. I found the IFTTT user interface to be kind of confusing, but you would configure the Docker webhook to post to https://maker.ifttt.com/trigger/`docker_xyz_image_built`/with/key/`your_key`.

如果你需要在本地构建，你至少可以通过在Docker Hub中创建一个连接到你感兴趣的repo的虚拟repo来解决上游映像更新时收到通知的问题。虚拟回购的唯一目的是在重新构建时触发一个webhook(这意味着它的一个链接回购被更新)。如果你能收到这个webhook，你甚至可以用它来触发你这边的重建。

更新:使用Dependabot - https://dependabot.com/docker/

BLUF:找到正确的插入点来监视容器的更改是一个挑战。如果DockerHub能解决这个问题，那就太好了。(存储库链接已经提到过，但注意在DockerHub上设置它们时-“每当在DockerHub上更新基本映像时，都会在此存储库中触发一个构建。只适用于非官方图片。”)

当我自己尝试解决这个问题时，我看到了几个webhook的建议，所以我想详细说明我使用过的几个解决方案。

Use microbadger.com to track changes in a container and use it's notification webhook feature to trigger an action. I set this up with zapier.com (but you can use any customizable webhook service) to create a new issue in my github repository that uses Alpine as a base image. Pros: You can review the changes reported by microbadger in github before taking action. Cons: Microbadger doesn't let you track a specific tag. Looks like it only tracks 'latest'. Track the RSS feed for git commits to an upstream container. ex. https://github.com/gliderlabs/docker-alpine/commits/rootfs/library-3.8/x86_64. I used zapier.com to monitor this feed and to trigger an automatic build of my container in Travis-CI anytime something is committed. This is a little extreme but you can change the trigger to do other things like open an issue in your git repository for manual intervention. Pros: Closer to an automated pipline. The Travis-CI build just checks to see if your container has issues with whatever was committed to the base image repository. It's up to you if your CI service takes any further action. Cons: Tracking the commit feed isn't perfect. Lots of things get committed to the repository that don't affect the build of the base image. Doesn't take in to account any issues with frequency/number of commits and any API throttling.

我不打算讨论您是否希望在生产中进行无人值守的更新(我认为不需要)。我只是把这个留在这里作为参考，以防有人觉得有用。在终端中使用以下命令将所有docker映像更新到最新版本:

# docker images | awk '(NR>1) && ($2!~/none/) {print $1":"$2}' | xargs -L1 docker pull

下面是一种自动更新docker容器的最简单方法

通过$ crontab -e放置作业:

0 * * * * sh ~/.docker/cron.sh

创建目录~/。Docker与文件cron.sh:

#!/bin/sh
if grep -Fqe "Image is up to date" << EOF
`docker pull ubuntu:latest`
EOF
then
    echo "no update, just do cleaning"
    docker system prune --force
else
    echo "newest exist, recompose!"
    cd /path/to/your/compose/file
    docker-compose down --volumes
    docker-compose up -d
fi

这里有很多答案，但没有一个符合我的需要。我想知道提问者第一个问题的确切答案。如何知道hub.docker.com上的图像何时更新?

下面的脚本可以每天运行。在第一次运行时，它从HUB注册中心获得标记的基线和更新日期，并将它们保存在本地。从那时起，每次运行它都会检查注册表中的新标记和更新日期。因为每当有新图像存在时，它都会改变，所以它会告诉我们基本图像是否发生了变化。以下是剧本:

#!/bin/bash

DATAPATH='/data/docker/updater/data'

if [ ! -d "${DATAPATH}" ]; then
        mkdir "${DATAPATH}";
fi
IMAGES=$(docker ps --format "{{.Image}}")
for IMAGE in $IMAGES; do
        ORIGIMAGE=${IMAGE}
        if [[ "$IMAGE" != *\/* ]]; then
                IMAGE=library/${IMAGE}
        fi
        IMAGE=${IMAGE%%:*}
        echo "Checking ${IMAGE}"
        PARSED=${IMAGE//\//.}
        if [ ! -f "${DATAPATH}/${PARSED}" ]; then
                # File doesn't exist yet, make baseline
                echo "Setting baseline for ${IMAGE}"
                curl -s "https://registry.hub.docker.com/v2/repositories/${IMAGE}/tags/" > "${DATAPATH}/${PARSED}"
        else
                # File does exist, do a compare
                NEW=$(curl -s "https://registry.hub.docker.com/v2/repositories/${IMAGE}/tags/")
                OLD=$(cat "${DATAPATH}/${PARSED}")
                if [[ "${VAR1}" == "${VAR2}" ]]; then
                        echo "Image ${IMAGE} is up to date";
                else
                        echo ${NEW} > "${DATAPATH}/${PARSED}"
                        echo "Image ${IMAGE} needs to be updated";
                        H=`hostname`
                        ssh -i /data/keys/<KEYFILE> <USER>@<REMOTEHOST>.com "{ echo \"MAIL FROM: root@${H}\"; echo \"RCPT TO: <USER>@<EMAILHOST>.com\"; echo \"DATA\"; echo \"Subject: ${H} - ${IMAGE} needs update\"; echo \"\"; echo -e \"\n${IMAGE} needs update.\n\ndocker pull ${ORIGIMAGE}\"; echo \"\"; echo \".\"; echo \"quit\"; sleep 1; } | telnet <SMTPHOST> 25"
                fi

        fi
done;

您可能需要更改顶部的DATAPATH变量，并更改末尾的电子邮件通知命令以满足您的需要。对我来说，我把它SSH到我的SMTP所在的另一个网络上的服务器上。但是您也可以轻松地使用邮件命令。

现在，您还需要检查容器本身中是否有更新的包。这实际上可能比在容器工作后“拉”更有效。以下是实现这一目标的脚本:

#!/bin/bash


function needsUpdates() {
        RESULT=$(docker exec ${1} bash -c ' \
                if [[ -f /etc/apt/sources.list ]]; then \
                grep security /etc/apt/sources.list > /tmp/security.list; \
                apt-get update > /dev/null; \
                apt-get upgrade -oDir::Etc::Sourcelist=/tmp/security.list -s; \
                fi; \
                ')
        RESULT=$(echo $RESULT)
        GOODRESULT="Reading package lists... Building dependency tree... Reading state information... Calculating upgrade... 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded."
        if [[ "${RESULT}" != "" ]] && [[ "${RESULT}" != "${GOODRESULT}" ]]; then
                return 0
        else
                return 1
        fi
}

function sendEmail() {
        echo "Container ${1} needs security updates";
        H=`hostname`
        ssh -i /data/keys/<KEYFILE> <USRER>@<REMOTEHOST>.com "{ echo \"MAIL FROM: root@${H}\"; echo \"RCPT TO: <USER>@<EMAILHOST>.com\"; echo \"DATA\"; echo \"Subject: ${H} - ${1} container needs security update\"; echo \"\"; echo -e \"\n${1} container needs update.\n\n\"; echo -e \"docker exec ${1} bash -c 'grep security /etc/apt/sources.list > /tmp/security.list; apt-get update > /dev/null; apt-get upgrade -oDir::Etc::Sourcelist=/tmp/security.list -s'\n\n\"; echo \"Remove the -s to run the update\"; echo \"\"; echo \".\"; echo \"quit\"; sleep 1; } | telnet <SMTPHOST> 25"
}

CONTAINERS=$(docker ps --format "{{.Names}}")
for CONTAINER in $CONTAINERS; do
        echo "Checking ${CONTAINER}"
        if needsUpdates $CONTAINER; then
                sendEmail $CONTAINER
        fi
done