我的应用程序包括设置了自动重启的相同微服务的多个实例。当一个实例重新启动时，它必须在数据库中需要时执行一些健全性检查和清理，但只有它自己的。
我使用的解决方案是在docker文件中声明一个环境变量来区分实例。假设我有两个实例，docker-file-for-instance-1包含：
ENV INSTANCE=1
和docker-file-for-instance-2包含：
ENV INSTANCE=2
使用此技巧，实例可以在重新启动后检查其自身工作的数据，该数据在列实例的帮助下记录在数据库中，该列获取环境变量INSTANCE的值。
但这种情况很严重。
编辑：在下面添加Tarun Lalwani解决方案以检查两个容器的UUID行为
test.sh
#!/bin/bash
echo "Building Image"
docker build -t c1i . > /dev/null
echo "Killing existing container if any"
for c in c1 c2; do
if [[ `docker ps --filter "name=$c" --format "{{.Names}}"` == $c ]]; then docker kill $c; docker rm $c; fi;
echo "Starting container $c in background"
docker run -d --name $c c1i > /dev/null
docker ps -a
echo "Restarting container $c"
docker restart $c > /dev/null
docker ps -a
done;
for c in c1 c2; do
echo "Restarting container $c again"
docker restart $c > /dev/null
docker ps -a
done;
for c in c1 c2; do
echo "Checking container $c logs"
docker logs $c
done;
docker ps -a
for c in c1 c2; do
echo "Checking container $c UUID"
docker exec $c cat /etc/environment.container
done;
echo "Killing containers"
for c in c1 c2; do
if [[ `docker ps --filter "name=$c" --format "{{.Names}}"` == $c ]]; then docker kill $c; docker rm $c; fi;
done;
init.sh
#!/bin/sh
ENV_FILE=/etc/environment.container
#cat $ENV_FILE
if [ -f $ENV_FILE ]; then
. $ENV_FILE
fi
if [ -z "${CONTAINER_UUID}" ]; then
echo "Starting container for the first time"
CONTAINER_UUID=$(uuidgen -r)
echo "CONTAINER_UUID=$CONTAINER_UUID" >> $ENV_FILE
echo "UUID of new container is $CONTAINER_UUID"
else
CONTAINER_UUID=${CONTAINER_UUID}
echo "Restarting container with $CONTAINER_UUID"
fi
echo "------------------ END OF CONTAINER INIT ----------------"
exec tail -f /dev/null
exit 0
dockerfile是一样的。
这是控制台输出：
$ ./test.sh
Building Image
Killing existing container if any
Starting container c1 in background
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 2 seconds ago Up Less than a second c1
Restarting container c1
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 14 seconds ago Up Less than a second c1
Starting container c2 in background
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8654d93936e c1i "/bin/sh -c /init.sh" 2 seconds ago Up Less than a second c2
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 16 seconds ago Up 2 seconds c1
Restarting container c2
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8654d93936e c1i "/bin/sh -c /init.sh" 15 seconds ago Up Less than a second c2
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 29 seconds ago Up 14 seconds c1
Restarting container c1 again
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8654d93936e c1i "/bin/sh -c /init.sh" 27 seconds ago Up 12 seconds c2
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 41 seconds ago Up Less than a second c1
Restarting container c2 again
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8654d93936e c1i "/bin/sh -c /init.sh" 39 seconds ago Up Less than a second c2
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 53 seconds ago Up 12 seconds c1
Checking container c1 logs
Starting container for the first time
UUID of new container is 432bfc77-e186-4ca2-bb9a-450b370d05a3
------------------ END OF CONTAINER INIT ----------------
Restarting container with 432bfc77-e186-4ca2-bb9a-450b370d05a3
------------------ END OF CONTAINER INIT ----------------
Restarting container with 432bfc77-e186-4ca2-bb9a-450b370d05a3
------------------ END OF CONTAINER INIT ----------------
Checking container c2 logs
Starting container for the first time
UUID of new container is 9eae8f6c-c332-422a-a35a-6ec1d59b6e6c
------------------ END OF CONTAINER INIT ----------------
Restarting container with 9eae8f6c-c332-422a-a35a-6ec1d59b6e6c
------------------ END OF CONTAINER INIT ----------------
Restarting container with 9eae8f6c-c332-422a-a35a-6ec1d59b6e6c
------------------ END OF CONTAINER INIT ----------------
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8654d93936e c1i "/bin/sh -c /init.sh" 39 seconds ago Up Less than a second c2
1cd1b7961f5a c1i "/bin/sh -c /init.sh" 53 seconds ago Up 12 seconds c1
Checking container c1 UUID
CONTAINER_UUID=432bfc77-e186-4ca2-bb9a-450b370d05a3
Checking container c2 UUID
CONTAINER_UUID=9eae8f6c-c332-422a-a35a-6ec1d59b6e6c
Killing containers
我尝试过其他两种解决方案，但没有设法让它们发挥作用：
Dockerfile（替代方案1 - 不起作用）
FROM ubuntu:16.04
RUN apt-get update -y && apt-get install uuid-runtime -y
COPY ./init2.sh /etc/init.d/init.sh
CMD chmod a+x /etc/init.d/init.sh
Dockerfile（替代方案2 - 不起作用）
FROM ubuntu:16.04
RUN apt-get update -y && apt-get install uuid-runtime -y
COPY ./init.sh /etc/rc.local
CMD chmod a+x /etc/rc.local
init2.sh（替代方案 - 无效）
#! /bin/sh
PATH=/sbin:/bin
do_start () {
ENV_FILE=/etc/environment.container
echo "exec init.sh on container :"
cat $ENV_FILE
if [ -f $ENV_FILE ]; then
. $ENV_FILE
fi
if [ -z "${CONTAINER_UUID}" ]; then
echo "Starting container for the first time"
CONTAINER_UUID=$(uuidgen -r)
echo "CONTAINER_UUID=$CONTAINER_UUID" >> $ENV_FILE
echo "UUID of new container is $CONTAINER_UUID"
else
CONTAINER_UUID=${CONTAINER_UUID}
echo "Restarting container with $CONTAINER_UUID"
fi
echo "------------------ END OF CONTAINER INIT ----------------"
#exec tail -f /dev/null
}
do_status () {
}
case "$1" in
start|"")
do_start
;;
restart|reload|force-reload|stop|status)
# No-op
;;
*)
;;
esac
exit 0
我在这做错了什么？
答案 0 :(得分：1)
好吧，我不会在容器外生成容器ID。我只会从容器内部生成它。
我找到了一个效果很好的样本。
<强> Dockerfile
FROM ubuntu:16.04
RUN apt-get update -y && apt-get install uuid-runtime -y
COPY ./init.sh /init.sh
CMD /init.sh
<强> init.sh
#!/bin/sh
ENV_FILE=/etc/environment.container
cat $ENV_FILE
if [ -f $ENV_FILE ]; then
. $ENV_FILE
fi
if [ -z "${CONTAINER_UUID}" ]; then
echo "Starting container for the first time"
CONTAINER_UUID=$(uuidgen -r)
echo "CONTAINER_UUID=$CONTAINER_UUID" >> $ENV_FILE
echo "UUID of new container is $CONTAINER_UUID"
else
CONTAINER_UUID=${CONTAINER_UUID}
echo "Restarting container with $CONTAINER_UUID"
fi
echo "------------------ END OF CONTAINER INIT ----------------"
exec tail -f /dev/null
然后创建了一个test.sh以查看功能
<强> test.sh
#!/bin/bash
echo "Building Image"
docker build -t c1i . > /dev/null
echo "Killing existing container if any"
docker kill c1 > /dev/null
docker rm c1 > /dev/null
echo "Starting container in background"
docker run -d --name c1 c1i > /dev/null
echo "Restarting container"
docker restart c1 > /dev/null
echo "Restarting container again"
docker restart c1 > /dev/null
echo "Checking container logs"
docker logs c1
以上测试的输出如下
Building Image
Killing existing container if any
Starting container in background
Restarting container
Restarting container again
Checking container logs
Starting container for the first time
UUID of new container is 23615a43-3b59-4369-82c7-0202ad227403
------------------ END OF CONTAINER INIT ----------------
cat: /etc/environment.container: No such file or directory
CONTAINER_UUID=23615a43-3b59-4369-82c7-0202ad227403
Restarting container with 23615a43-3b59-4369-82c7-0202ad227403
------------------ END OF CONTAINER INIT ----------------
CONTAINER_UUID=23615a43-3b59-4369-82c7-0202ad227403
Restarting container with 23615a43-3b59-4369-82c7-0202ad227403
------------------ END OF CONTAINER INIT ----------------
正如您所看到的那样，环境变量始终是唯一的，因为它是基于UUID的，并且在重新启动同一容器后会保持不变