This is a short introduction to Mesos meant to get you familiar with spinning up and running a small mesos cluster.
- Video of this demo: https://www.youtube.com/watch?v=PdSmMT0IGx4
- Slides - https://speakerdeck.com/micahhausler/introduction-to-mesos
This guide requires Docker installed from docker-toolbox with at least version 1.11.0. Older versions may work, but no guarantees are made.
The following links and the provided configuration files assume that your
default and secondary docker VM's have the addresses of 192.168.99.100 and
192.168.99.101. If yours differ, you will have to modify the configuration
and compose files with your docker VM IP addresses.
docker-compose build
docker-compose create
docker-compose start zookeeper
You'll have to wait a minute for Zookeeper to spin up, which you can watch at the exhibitor endpoint, on port 8181.
Once zookeeper is in a "serving" state, you can start the rest of the services:
docker-compose start
You can then open:
Runing a second slave is entirely optional, but will help demonstrate load balancing later on. To run a second slave using docker-machine, first create the machine:
./create-machines.sh
eval $(docker-machine env mesos2)
docker-compose -f docker-compose-slave.yml build
docker-compose -f docker-compose-slave.yml up -d
You may have to edit the docker-compose-slave.yml to update the IP addresses
for your VMs if the address is not 192.168.99.101
mesos-dns is an open-source DNS that uses Mesos for describing where tasks are running.
Run the provided update-resolv.sh script in order for each VM to use the
mesos-dns resolver.
./update_resolv.sh setup
After you are done running mesos, run the cleanup command so the VM reverts to its original nameserver
./update_resolv.sh cleanup
Chronos is a distributed cron system that
runs on Mesos. You can run it on marathon with the create-app.sh script.
./create-app.sh chronos
This POSTs the contents of ./apps/chronos.json over to marathon to run the task.
Open the app in the Marathon UI and after a minute you should see a running task with the status of "Healthy". In the "ID" column, you'll see a task-name and with an IP address and port. Click the IP address and you'll be redirected to the Chronos UI.
You can also use mesos-dns to find where chronos is running. See the mesos-dns docs for more information.
dig _chronos._tcp.marathon.mesos @192.168.99.100 SRV
The file ./apps/nginx.json is an example application that just runs a docker
image of nginx.
./create-app.sh nginx
If you navigate to the Marathon UI, You should see 2 instances of nginx staging and eventually running. You can also query the mesos-dns to see where each instance is running:
dig _nginx._tcp.marathon.mesos @192.168.99.100 SRV
Also be sure to check out the Mesos master UI, and click the "Sandbox" link for each running task. There you can see the STDERR and STDOUT of each task.
Like the previous tasks, the file ./apps/marathon-lb.json contains a
definition for running marathon-lb
load balancer on Mesos. Marathon-lb is HAProxy that
gets updated based on events from Marathon.
./create-app.sh marathon-lb
You now have a loadbalancer that is running on Mesos! You can see the HAProxy
stats page running on each of your load balancers at the endpoint
:9090/haproxy?stats or http://192.168.99.100:9090/haproxy?stats
Tip: Add the following two lines to you're host machine's /etc/hosts file
to easily navigate to the load balancer in your web browser.
192.168.99.100 nginx.docker.local
192.168.99.101 nginx.docker.local
or run
echo "\n192.168.99.100 nginx.docker.local\n192.168.99.101 nginx.docker.local" | sudo tee -a /etc/hosts
Once you have that /etc/hosts entry in place, you can go to
http://nginx.docker.local and your traffic will be
load balanced!
I've found that when running the Mesos agent in docker, it must be run with the following docker flags:
--pid=host --net=host --privileged
and the mesos agent flags as provided in docker-compose.yml
MIT License. See LICENSE