发布于 2015-09-10 16:08:36 | 426 次阅读 | 评论: 0 | 来源: 网络整理

注解

Traditionally a Docker container runs a single process when it is launched, for example an Apache daemon or a SSH server daemon. Often though you want to run more than one process in a container. There are a number of ways you can achieve this ranging from using a simple Bash script as the value of your container’s CMD instruction to installing a process management tool.

In this example we’re going to make use of the process management tool, Supervisor, to manage multiple processes in our container. Using Supervisor allows us to better control, manage, and restart the processes we want to run. To demonstrate this we’re going to install and manage both an SSH daemon and an Apache daemon.

创建一个Dockerfile

Let’s start by creating a basic Dockerfile for our new image.

FROM ubuntu:latest
MAINTAINER examples@docker.io
RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe" > /etc/apt/sources.list
RUN apt-get update
RUN apt-get upgrade -y

安装Supervisor

We can now install our SSH and Apache daemons as well as Supervisor in our container.

RUN apt-get install -y openssh-server apache2 supervisor
RUN mkdir -p /var/run/sshd
RUN mkdir -p /var/log/supervisor

Here we’re installing the openssh-server, apache2 and supervisor (which provides the Supervisor daemon) packages. We’re also creating two new directories that are needed to run our SSH daemon and Supervisor.

添加Supervisor的配置文件

Now let’s add a configuration file for Supervisor. The default file is called supervisord.conf and is located in /etc/supervisor/conf.d/.

ADD supervisord.conf /etc/supervisor/conf.d/supervisord.conf

Let’s see what is inside our supervisord.conf file.

[supervisord]
nodaemon=true

[program:sshd]
command=/usr/sbin/sshd -D

[program:apache2]
command=/bin/bash -c "source /etc/apache2/envvars && exec /usr/sbin/apache2 -DFOREGROUND"

The supervisord.conf configuration file contains directives that configure Supervisor and the processes it manages. The first block [supervisord] provides configuration for Supervisor itself. We’re using one directive, nodaemon which tells Supervisor to run interactively rather than daemonize.

The next two blocks manage the services we wish to control. Each block controls a separate process. The blocks contain a single directive, command, which specifies what command to run to start each process.

暴露端口ports并运行Supervisor

Now let’s finish our Dockerfile by exposing some required ports and specifying the CMD instruction to start Supervisor when our container launches.

EXPOSE 22 80
CMD ["/usr/bin/supervisord"]

Here we’ve exposed ports 22 and 80 on the container and we’re running the /usr/bin/supervisord binary when the container launches.

创建我们的容器

We can now build our new container.

sudo docker build -t <yourname>/supervisord .

运行我们Supervisor容器

Once we’ve got a built image we can launch a container from it.

sudo docker run -p 22 -p 80 -t -i <yourname>/supervisor
2013-11-25 18:53:22,312 CRIT Supervisor running as root (no user in config file)
2013-11-25 18:53:22,312 WARN Included extra file "/etc/supervisor/conf.d/supervisord.conf" during parsing
2013-11-25 18:53:22,342 INFO supervisord started with pid 1
2013-11-25 18:53:23,346 INFO spawned: 'sshd' with pid 6
2013-11-25 18:53:23,349 INFO spawned: 'apache2' with pid 7
. . .

We’ve launched a new container interactively using the docker run command. That container has run Supervisor and launched the SSH and Apache daemons with it. We’ve specified the -p flag to expose ports 22 and 80. From here we can now identify the exposed ports and connect to one or both of the SSH and Apache daemons.

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