Bash脚本命令等待docker-compose过程完成后再继续 [英] Bash script command to wait until docker-compose process has finished before moving on

问题描述

我们有一个bash脚本来安装程序，其中包括运行 docker-compose 文件.其中一项服务RabbitMQ需要花费一些时间来加载，因此我需要一个命令来等待其加载，然后再加载其他服务.我们使用的是 sleep 命令，但是我们的客户使用不同的笔记本电脑，因此在某些笔记本电脑上的加载时间要比其他笔记本电脑更长.有没有办法在不使用 sleep 命令的情况下，一直保持它直到完成加载服务，然后再继续进行下一个操作?我已经在下面包含了脚本的一部分.谢谢！

We have a bash script that installs a program, which includes running a docker-compose file. One of the services, RabbitMQ, takes some time to load and I need a command to wait until it's loaded before the other services are loaded. We were using a sleep command, but our customers use different laptops, so it takes longer to load on some than others. Is there a way to just hold it until it finishes loading the service before moving on to the next without using the sleep command? I have included the part of the script below. Thanks!

# Execute applications
cd /opt/program
docker-compose up -d
echo "waiting for message queue..."
sleep 15

echo "starting ingest manager"

cd /opt/program/scripts
chmod +x start-manager.sh
./start-manager.sh &

推荐答案

正如其他答案中已经提到的那样，您将必须对容器进行特定于应用程序的准备情况检查.就我个人而言，我更喜欢为这些检查/脚本提供容器图片，例如通过添加 wait-for-it.sh (请参见 ErikMD的答案)或类似的脚本映像并在运行容器中执行它们，例如与 docker exec (由 Ahmed Arafa的答案所建议).

As already stated in the other answers you'll have to do an application-specific readiness-check for your container. Personally I prefer to provide these checks/scripts with the container image, e.g. by adding the wait-for-it.sh (see ErikMD's answer) or similar scripts to the image and executing them within the running container e.g. with docker exec (as proposed by Ahmed Arafa's answer).

与在主机上运行检查相比，它具有一些优势:

This has some advantages over running the check on the host:

• 您可以在容器映像中提供所有必需的脚本和依赖项
• 您不需要对主机进行任何假设(例如，通过api端点进行测试时:主机上是否可以使用 wget / curl ，甚至不需要 bash /shell? docker / docker-compose 命令是否在与docker deamon相同的主机上执行，即您能否通过 localhost ?)
• 您不必将任何端口/端点暴露给外界仅用于检查容器状态
• 您可以为图像的不同版本提供不同的检查脚本，而无需修改启动脚本

• you can provide all required scripts and dependencies with the container image
• you don't need to make any assumptions about the host (e.g. when testing via an api endpoint: is wget/curl available on the host, or even a bash/shell? Is the docker/docker-compose command executed on the same host as the docker deamon, i.e. could you reach the container via localhost?)
• you don't have to expose any ports/endpoints to the outside world only for checking container status
• you can provide different check scripts with different versions of the image without having to modify the start script

因此，要将这种方法应用于您的示例，只需添加一个脚本-例如 is_ready.sh -转到图像，使用 docker-compose exec 在容器中执行它，并根据其退出状态采取行动:

So, to apply this method to your example, simply add a script - e.g. is_ready.sh - to the image, execute it within the container with docker-compose exec and act upon its exit status:

# Execute applications
cd /opt/program
docker-compose up -d
echo "waiting for message queue..."

while ! docker-compose exec rabbitmq /is_ready.sh; sleep 1; done

echo "starting ingest manager"

cd /opt/program/scripts
chmod +x start-manager.sh
./start-manager.sh &

其中 is_ready.sh 可能看起来像这样:

where is_ready.sh may look like this:

#!/bin/bash

rabbitmqctl status

---

沿着这条路走得更远，您可以利用 docker 和 docker-compose .有了这些 docker ，它们将自动执行定义的运行状况检查脚本/命令，并在容器状态中指示当前运行状况.

---

Going even further down this road you may leverage the native healtcheck feature of docker and docker-compose. With these docker will automatically execute the defined healthcheck script/command and indicate the current health in the container status.

合并到您的脚本中后，可能看起来像这样:

Incorporated into your script this could look like:

# Execute applications
cd /opt/program
docker-compose up -d
echo "waiting for message queue..."

is_healthy() {
    service="$1"
    container_id="$(docker-compose ps -q "$service")"
    health_status="$(docker inspect -f "{{.State.Health.Status}}" "$container_id")"

    if [ "$health_status" = "healthy" ]; then
        return 0
    else
        return 1
    fi
}

while ! is_healthy rabbitmq; do sleep 1; done

echo "starting ingest manager"

cd /opt/program/scripts
chmod +x start-manager.sh
./start-manager.sh &

具有在 docker-compose.yml

...
services:
  rabbitmq:
    ...
    healtcheck:
      test: rabbitmqctl status      

要进行更复杂的运行状况检查，您还可以在图像中添加更长的脚本，然后执行该脚本.

For more complex healthchecks you can also add a longer script to the image and execute that instead.

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