From 297d6c04a31f39ff24fcebad8d82c43e0bcf6900 Mon Sep 17 00:00:00 2001 From: Robin Naundorf Date: Thu, 14 Apr 2016 15:21:07 +0200 Subject: [PATCH] closes #11703 closes #11560 Signed-off-by: Robin Naundorf --- docs/admin/cfengine_process_management.md | 150 ---------------------- 1 file changed, 150 deletions(-) delete mode 100644 docs/admin/cfengine_process_management.md diff --git a/docs/admin/cfengine_process_management.md b/docs/admin/cfengine_process_management.md deleted file mode 100644 index be62e410c2..0000000000 --- a/docs/admin/cfengine_process_management.md +++ /dev/null @@ -1,150 +0,0 @@ - - -# Process management with CFEngine - -Create Docker containers with managed processes. - -Docker monitors one process in each running container and the container -lives or dies with that process. By introducing CFEngine inside Docker -containers, we can alleviate a few of the issues that may arise: - - - It is possible to easily start multiple processes within a - container, all of which will be managed automatically, with the - normal `docker run` command. - - If a managed process dies or crashes, CFEngine will start it again - within 1 minute. - - The container itself will live as long as the CFEngine scheduling - daemon (cf-execd) lives. With CFEngine, we are able to decouple the - life of the container from the uptime of the service it provides. - -## How it works - -CFEngine, together with the cfe-docker integration policies, are -installed as part of the Dockerfile. This builds CFEngine into our -Docker image. - -The Dockerfile's `ENTRYPOINT` takes an arbitrary -amount of commands (with any desired arguments) as parameters. When we -run the Docker container these parameters get written to CFEngine -policies and CFEngine takes over to ensure that the desired processes -are running in the container. - -CFEngine scans the process table for the `basename` of the commands given -to the `ENTRYPOINT` and runs the command to start the process if the `basename` -is not found. For example, if we start the container with -`docker run "/path/to/my/application parameters"`, CFEngine will look for a -process named `application` and run the command. If an entry for `application` -is not found in the process table at any point in time, CFEngine will execute -`/path/to/my/application parameters` to start the application once again. The -check on the process table happens every minute. - -Note that it is therefore important that the command to start your -application leaves a process with the basename of the command. This can -be made more flexible by making some minor adjustments to the CFEngine -policies, if desired. - -## Usage - -This example assumes you have Docker installed and working. We will -install and manage `apache2` and `sshd` -in a single container. - -There are three steps: - -1. Install CFEngine into the container. -2. Copy the CFEngine Docker process management policy into the - containerized CFEngine installation. -3. Start your application processes as part of the `docker run` command. - -### Building the image - -The first two steps can be done as part of a Dockerfile, as follows. - - FROM ubuntu - MAINTAINER Eystein Måløy Stenberg - - RUN apt-get update && apt-get install -y wget lsb-release unzip ca-certificates - - # install latest CFEngine - RUN wget -qO- http://cfengine.com/pub/gpg.key | apt-key add - - RUN echo "deb http://cfengine.com/pub/apt $(lsb_release -cs) main" > /etc/apt/sources.list.d/cfengine-community.list - RUN apt-get update && apt-get install -y cfengine-community - - # install cfe-docker process management policy - RUN wget https://github.com/estenberg/cfe-docker/archive/master.zip -P /tmp/ && unzip /tmp/master.zip -d /tmp/ - RUN cp /tmp/cfe-docker-master/cfengine/bin/* /var/cfengine/bin/ - RUN cp /tmp/cfe-docker-master/cfengine/inputs/* /var/cfengine/inputs/ - RUN rm -rf /tmp/cfe-docker-master /tmp/master.zip - - # apache2 and openssh are just for testing purposes, install your own apps here - RUN apt-get update && apt-get install -y openssh-server apache2 - RUN mkdir -p /var/run/sshd - RUN echo "root:password" | chpasswd # need a password for ssh - - ENTRYPOINT ["/var/cfengine/bin/docker_processes_run.sh"] - -By saving this file as Dockerfile to a working directory, you can then build -your image with the docker build command, e.g., -`docker build -t managed_image`. - -### Testing the container - -Start the container with `apache2` and `sshd` running and managed, forwarding -a port to our SSH instance: - - $ docker run -p 127.0.0.1:222:22 -d managed_image "/usr/sbin/sshd" "/etc/init.d/apache2 start" - -We now clearly see one of the benefits of the cfe-docker integration: it -allows to start several processes as part of a normal `docker run` command. - -We can now log in to our new container and see that both `apache2` and `sshd` -are running. We have set the root password to "password" in the Dockerfile -above and can use that to log in with ssh: - - ssh -p222 root@127.0.0.1 - - ps -ef - UID PID PPID C STIME TTY TIME CMD - root 1 0 0 07:48 ? 00:00:00 /bin/bash /var/cfengine/bin/docker_processes_run.sh /usr/sbin/sshd /etc/init.d/apache2 start - root 18 1 0 07:48 ? 00:00:00 /var/cfengine/bin/cf-execd -F - root 20 1 0 07:48 ? 00:00:00 /usr/sbin/sshd - root 32 1 0 07:48 ? 00:00:00 /usr/sbin/apache2 -k start - www-data 34 32 0 07:48 ? 00:00:00 /usr/sbin/apache2 -k start - www-data 35 32 0 07:48 ? 00:00:00 /usr/sbin/apache2 -k start - www-data 36 32 0 07:48 ? 00:00:00 /usr/sbin/apache2 -k start - root 93 20 0 07:48 ? 00:00:00 sshd: root@pts/0 - root 105 93 0 07:48 pts/0 00:00:00 -bash - root 112 105 0 07:49 pts/0 00:00:00 ps -ef - -If we stop apache2, it will be started again within a minute by -CFEngine. - - service apache2 status - Apache2 is running (pid 32). - service apache2 stop - * Stopping web server apache2 ... waiting [ OK ] - service apache2 status - Apache2 is NOT running. - # ... wait up to 1 minute... - service apache2 status - Apache2 is running (pid 173). - -## Adapting to your applications - -To make sure your applications get managed in the same manner, there are -just two things you need to adjust from the above example: - - - In the Dockerfile used above, install your applications instead of - `apache2` and `sshd`. - - When you start the container with `docker run`, - specify the command line arguments to your applications rather than - `apache2` and `sshd`.