# Intro

This guide is meant to provide a quick way to learn about Re-ops and its capabilities, a more in-depth coverage is provided under the configuration guide.

By the end of it you should be able to:

  • Quickly create LXC instances using Re-core creation DSL
  • Run distributed Clojure functions on your local container cluster.
  • Monitor, query and analyse the state of the container instances.
  • Gain good understanding of the core capabilities of Re-ops.

# Installation

Setup prerequisites:

Note: The automated setup process will install LXD and additional tooling, make sure to run the following on a machine you are comfortable with making those changes to.

If you haven't already make sure to install Amazon corretto JDK 11:

wget https://corretto.aws/downloads/latest/amazon-corretto-11-x64-linux-jdk.deb
sudo dpkg -i amazon-corretto-11-x64-linux-jdk.deb
sudo apt-get -f install

We will use Re-cipes (opens new window) in order to setup Re-ops and LXD:

wget https://github.com/re-ops/re-cipes/releases/download/0.3.11/re-cipes -P /tmp
chmod +x /tmp/re-cipes
git clone https://github.com/re-ops/re-cipes.git ~/re-cipes
cp -r ~/re-cipes/resources /tmp

Make sure to adjust the user and home settings in /tmp/resources/config.edn to match your user:

# default user is re-ops
cat /tmp/resources/config.edn
 :user "re-ops"
 :home "/home/re-ops"

Now launch Re-cipes and let it run through:

sudo /tmp/re-cipes provision --plan re-cipes.profiles/re-ops-standalone

# Image

Next we will create a base container image on which our Re-core containers will be based upon:

cd ~/code/re-ops/re-pack
cat ~/.ssh/id_rsa.pub > http/authorized_keys
packer build -var 'user=re-ops' src/lxd/ubuntu-20.04/ubuntu-20.04-server-amd64.json

Check Re-pack more detailed information on creating Re-ops ready images on multiple hypervisors.

# Elasticsearch

We will use a local docker container in order to spin up Elasticsearch quickly:

sudo systemctl start docker-compose@elasticsearch.service

Check Re-dock for running ELK + Grafana in addition to Elasticsearch.

# Launch

We will launch the REPL:

cd ~/code/re-ops/re-core
# going to take a while as dependencies and Lein are downloaded
lein repl

Now we will start the system and create our first instance!:

; creating a type for the system that we will create next
(create cog 're-cipes.profiles/lean default-src :lean "")
; our first container based system
(create lxc defaults c1-medium local :lean "Our first running instance!")

# Run

Once the container is running we can deploy Re-gent into it, we start with building it:

cd ~/code/re-ops/re-gent
# allow ZeroMQ traffic
sudo ufw allow 9000

Back in the REPL we deploy the agent and run a function once the host is registered:

; assumes change your home path to match
(deploy (hosts (matching (*1)) :ip) "/home/re-ops/code/re-ops/re-gent/target/re-gent")
; wait couple of seconds to see the registered host
; run a distributed datalog query on the hosts grabbing jvm version
(run-hosts (hosts (matching (*1)) :hostname) re-cog.facts.datalog/run-query ['[:find ?v :where [_ :java/version ?v]]] [10 :second])

Next we will monitoring our instance cpu and ram usage:

; installing sysstat in order to measure cpu performance
(install (hosts identity :hostname) "sysstat")
; cpu usage stats
(cpu-persist (hosts identity :hostname))
; RAM usage stats
(ram-persist (hosts identity :hostname))

Both ram-persist and cpu-persist are a part of Re-mote:

  • Save the information into Elasticsearch where we can use Grafana and Kibana dashboards to visualize them.
  • Ship events to Riemann where we can define alerts on.

Check the scheduling section on how to enable on going monitoring tasks.