System Containers in RancherOS<\/h2>\n
First, for anyone who isn\u2019t familiar with RancherOS, it is a minimal
\ndistribution of Linux designed specifically to run Docker. RancherOS
\nruns a Docker daemon as PID 1, a role typically occupied by the init
\nsystem or systemd in most distributions. This daemon runs essential
\nsystem services like SSH, syslog or NTP as containers, and is called
\nsystem docker.<\/p>\n
A second Docker daemon, called user docker, is launched as a
\ncontainer. This is where any new containers started by the user are
\ncreated, as well as containers placed by Rancher or other management
\nservices.<\/p>\n
To give the Nagios agent access to all of the data from the server, as
\nwell as the system and user containers, it should run in the system
\ndocker instance. I will run this setup in 2 Vagrant virtual machines.<\/p>\n
Set up Rancher<\/strong><\/p>\n Even though we could monitor RancherOS with Nagios directly, I\u2019m going You can find my new Vagrant file here: The first step (after installing Vagrant, of course) is to clone this # The number of VMs will be added to the following string, * *<\/p>\n Leave $n_rancher at 1 for now.<\/p>\n After editing this file, run `vagrant up\u2019.<\/p>\n Vagrant will now first setup the Rancher VM, which means Vagrant will When finished, browse to the Rancher IP (http:\/\/192.168.0.200:8080\/<\/a> in The next task is to set up the Nagios Agent on the RancherOS instance.<\/p>\n For that you will need to log in to the server, which you do by running There you will have access to the user docker (by calling `docker`) A system container is not different from your usual docker container, sudo system-docker run -d –net=host –name nagios-agent buster\/nagios-agent<\/p>\n This nagios agent container comes with a minimal configuration to check In order for the Nagios agent to make any sense, we will also need a This is as easy as any other Rancher deployment, by clicking on \u201cAdd There we will make use of the already existing Nagios Server docker Add this container and after a while, the Nagios Server will be up and The Nagios Server only knows itself right now, so we will need to This can be done in \/opt\/nagios\/etc\/conf.d\/rancher1.cfg, for example.<\/p>\n Rancher offers a very nice terminal into the running containers, which Now, you can edit the config file by running `nano Add the following lines to the file:<\/p>\n define command{ Afterwards you can check if the configuration file format is correct by To check that the nrpe server on the second host is running you can also After you have verified the working Nagios setup you simply need to Now, you can login to Nagios again and see the Nagios Plugins doing Conclusion<\/strong><\/p>\n Using Nagios to monitor multiple RancherOS servers is as easy as running Starting a system docker container requires a few additional steps In the next few weeks RancherOS will ship 0.3, which includes support If you\u2019d like to get started with RancherOS, you can download it from Sebastian Schulze is a Technology Consultant from Germany, with
\nto set up Rancher in this deployment to manage the containers we create.
\nThe Rancher team provides a Vagrantfile to run RancherOS in a VM here:
\nhttps:\/\/github.com\/rancher\/os-vagrant<\/a> and
\nanother Vagrantfile for Rancher here:
\nhttps:\/\/github.com\/rancher\/rancher<\/a>
\nBut, since I want to have both in one Vagrant setup, I merged both
\nVagrantfiles into one and added the option to run multiple RancherOS
\ninstances in one.<\/p>\n
\n[https:\/\/github.com\/buster\/rancher-tutorial<\/a>]{.c10}<\/p>\n
\nrepository and edit the Vagrantfile to match your IP addresses in the
\nlines:<\/p>\n
\n# so Rancher will be on 192.168.0.200, the first RancherOS instance on 192.168.0.201, etc.
\n$rancher_ip_start = “192.168.0.20”
\n$rancherui_ip = $rancher_ip_start + “0”
\n# the number of rancher instances
\n$n_rancher = 1<\/p>\n
\ndownload the Virtualbox image, start it and Docker will then download
\nand run the Rancher Server and the Rancher Agent. Afterwards, the second
\nVM, which will host our RancherOS instance, will be started and the
\nRancherOS instance will register itself at the Rancher Server.<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_FD14F41B-EFA1-2421-89A2-A4A63C8F6507.jpg\")
<\/a><\/p>\n
\nmy case) and observe your new and shiny VMs:<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_2202D027-4152-E66D-D736-B1B33374F81A.jpg\")
<\/a><\/p>\nAdding a System Container to Rancher<\/strong><\/h2>\n
\n`vagrant ssh rancher1`.<\/p>\n
\nand to the system docker by calling `sudo system-docker`.<\/p>\n
\nexcept that it is run by the system docker and that has no networking by
\ndefault. Thus, it needs to inherit the network of the host (–net=host
\nparameter):<\/p>\n
\nthe load on the second RancherOS
\ninstance.![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_B644FD77-AB6D-20C4-B5C7-785561B4D1B5.jpg\")
<\/a><\/p>\n[]Deploying the Nagios Server to Rancher<\/h2>\n
\nNagios Server which polls the Nagios Agent.<\/p>\n
\nContainer\u201d in the Rancher UI.<\/p>\n
\ncontainer from
\nhttps:\/\/registry.hub.docker.com\/u\/cpuguy83\/nagios\/<\/a>
\nAlso don\u2019t forget to go to the `Ports` tab and map port 80 to port
\n8081 so that you can login on nagios.<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_2D3F87C5-1294-AF8A-6E3B-8E8E4584CEC0.jpg\")
<\/a><\/p>\n
\nrunning! Browse to
\nhttp:\/\/192.168.0.200:8081\/<\/a> and
\nobserve the Nagios UI running. The default username is
\nnagiosadmin and the password is nagios.<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_354527B2-5C76-D1A8-F672-F35218219983.jpg\")
<\/a><\/p>\n[]Configure Nagios Server<\/h2>\n
\nconfigure it to poll the Nagios Agent.<\/p>\n
\nyou can reach by click on the container and afterwards on the \u201cexecute
\nshell\u201d url:<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_CE1B5157-4299-1A1A-F7F5-E75C411AFE63.jpg\")
<\/a><\/p>\n
\n\/opt\/nagios\/etc\/conf.d\/rancher1.cfg`.<\/p>\n
\ncommand_name check_nrpe
\ncommand_line $USER1$\/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
\n}
\ndefine host{
\nuse linux-server
\nhost_name rancher1
\naddress 192.168.0.201
\n}
\ndefine service{
\nuse linux-server
\nhost_name rancher1
\nservice_description Current Users
\ncheck_command check_nrpe!check_users
\n}
\ndefine service{
\nuse generic-service
\nhost_name rancher1
\nservice_description Current Load
\ncheck_command check_nrpe!check_load
\n}<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/t_C791AD85-CB94-671F-9489-99B68EFB97DD.jpg\")
<\/a><\/p>\n
\nrunning `nagios -v \/opt\/nagios\/etc\/nagios.cfg`.<\/p>\n
\nrun a check manually: `\/opt\/nagios\/libexec\/check_nrpe -H
\n192.168.0.201 -c check_load`<\/p>\n
\nrestart the Nagios Server container by clicking on the symbol:<\/p>\n![\"\"](\"http:\/\/rancher.com\/wp-content\/uploads\/2015\/04\/9E3C674C-5BC3-568D-8374-886410485976.jpg\")
<\/p>\n
\ntheir work:<\/p>\n
\na preconfigured publicly available Docker container from
\nhttps:\/\/registry.hub.docker.com<\/a><\/p>\n
\ncompared to running a user container, but hopefully we\u2019ve explained
\nthem clearly here.<\/p>\n
\nfor predefined system services. That will make configuration of new
\nagents in the Nagios server as easy as executing a docker run command.<\/p>\n
\nGitHub here. Also, we\u2019re always demoing new features and answering lots
\nof questions at each months Rancher Meetup, which you can find a link
\nto for below.<\/p>\n
\nexperience in Linux, Solaris, Docker, and Vagrant. You can contact him
\nvia github at:
\nhttps:\/\/github.com\/buster<\/a><\/p>\n