Presentation given at AutoMacon on September 16, 2015 in Portland, OR. This talk covered how to build CoreOS components on Debian using Ansible and a brief demonstration of running an ELKStack application on the new cluster.

1. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Inserting CoreOS DNA for
Creating Docker Clusters.
Advanced Technology Group
September 16th, 2015

2. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Inserting CoreOS DNA for
Creating Docker Clusters.
Why? What’s the goal of this presentation?

3. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
About the speaker
● Patrick Galbraith
● HP Advanced Technology Group
● Has worked at Blue Gecko, MySQL AB, Classmates,
Slashdot, Cobalt Group, US Navy, K-mart
● MySQL projects: memcached UDFs, DBD::mysql,
Ansible HP switch drivers
● federated storage engine
● Family
● Outdoors

4. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.4
Enterprise workloads are migrating towards
Docker
Server
Host OS
Docker
bins+libs
Workload
B
Workload
A
bins+libs
Docker
Server
Host OS
Hypervisor
Guest OSGuest OS
bins+libs
Workload
B
Workload
A
bins+libs
Virtual
Machine
Docker is Great
• Lightweight “container” technology.
• Intelligent Packaging – Docker Images
• Intelligent Deployment – Docker
Containers
• Rapidly evolving ecosystem.
• Linux IS the API.
Docker has some gaps
• Scalability: Docker is a host application.
• Not Multi-Tenant.
• No comprehensive Host-to-Host
networking.
• Host OS maintenance is not included.
• No workload (Docker Container)
distribution.

5. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.5
Clustering Docker – What’s Important
Coordination
Configuration + discovery for the base cluster, and
applications.
Deployment Deploy a Docker Image to some node in the cluster.
Scheduler Place containers efficiently on to the cluster.
Network Inter-Host networking is obscured in the default Docker model.
The default model uses an internal only bridge.
Maintenance
Install & update the base system in a scalable and effective
way.
Note: Docker provides its own system: Images & Containers.

6. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.6
Existing Approaches to Clustering Docker
• Coreos
• Kubernetes
• Swarm
• Docker Machine
• Project Atomic
• Apache Mesos
• RancherOS

7. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
CoreOS DNA
The Clustered
Docker Proof of
Concept

8. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.8
Use Cases:
• In Cloud
• Moonshot
• Bare metal
Single Node – CoreOS DNA
Linux Kernel
etcd
fleetd
Base System
CoreOS DNA Node
dockerd
Docker Containers
systemd
App Container
1
App Container
…
Port: 4001
Fleetctl interacts with
fleetd by directly
changing values in
etcd.
etcdctl
Client(s)
fleetctl

9. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.9
CoreOS DNA Cluster
Cluster Configuration – CoreOS DNA
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd…
etcd Discovery
Server
etcd
http://discovery.etcd.io
Docker
Registry
Images
Discovery
Control Node
(jump box)
etcdctl
fleetctl
ssh
1
2
3
1. Cluster Start
(etcd
discovery)
2. Container Start
( fleetctl )
3. Docker
Download

10. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.10
Networking as deployed – CoreOS DNA
eth0
Linux Kernel
etcd
fleetd
CoreOS DNA Node
dockerd
Docker Containers
Container
Container
Container
Container
docker0
172.x.x.x
iptables
port
mapping
Netfilter
CoreOS
DNA Node
CoreOS
DNA Node
CoreOS
DNA Node
Neutron Router
10.x.x.
x
Public
Internet
15.x.x.
x
NA
T
172.x.x.x - Docker Internal
10.x.x.x - Host (private) Network
15.x.x.x - Public (NAT’ed)
Addresses

11. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.11
ELK Stack + Sinatra Worker Agents (ELK - Elasticsearch, Logstash, Kibana)
Example Application – CoreOS DNA
CoreOS DNA Cluster
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd
CoreOS DNA Node
Docker
Containers etcd
fleetd
dockerd
systemd…
Agent “@5001”
Agent “@5003”
Agent “@5002”
Agent “@5000”
Nginx Logstash
Elasticsearch
+ Kabanna Docker
Images
Fleet Mapped
(scheduled into)
Docker
Containers

12. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Building the POC

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Building the cluster Using Ansible
Ansible Modules
• Nova_compute – to launch instances
• Nova_facts – used to build inventory files for launched instances
• Docker and docker_facts – used to run containers outside of fleet (testing) and
verification
• Docker_pull – pre-pull images on instances for faster launch by systemd (via fleet)
Using Ansible to provision etcd and build clusters
• query discovery URL
• write URL to local file ad set as a variable
• render etcd service file with the variable
• Build, configure, and run etcd
• Build, configure and run Fleet

14. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.14
The Special Sauce
Etcd
• Integral to cluster functioning.
• Fleet communicates with etcd to obtain key/values from etcd.
• Etcd also used by the sample ELK app to store key/value pairs used by confd to render
config files upon running containers (boot).
Confd
• Stored in each Docker container.
• Keeps an eye on files rendered.
• Can use etcd key/value pairs to interpolate what it rendered.
• Automatically keeps config files up to date with etcd information.

15. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.15
Sample App unit files
Systemd unit files
• Unit file directives
– ExecStartPre – pull image
– ExecStart – run container
– ExecStartPost– set IP of the container in etcd
– ExecStopPost – remove IP in etcd upon container stop
• ElasticSearch – sets its own public and private IPs in etcd for discovery by logstash
• Logstash – sets its own IP in etcd for discovery by logstash agents
• Sinatra app – sets title of app in etcd as well as IP addresses for discovery by nginx to
generate nginx conf using confd

16. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.16
Sample App container Dockerfiles
Docker file functionality
• ElasticSearch – install confd, install and configure elasticsearch, install kopf and kibana
plugins,expose port 9200, launch
• Logstash – Install confd, Install and configure logstash, run boot script
• Sinatra – Install sinatra, confd, place logstash agent, expose port 5000, run boot.sh
• Nginx – Install nginx, confd, run boot.sh

17. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.17
Sample App container CMD scripts
Boot Script
• Logstash – render logstash config (confd –onetime), generate SSL private key and cert,
stores in etcd, then run logstash
• Sinatra – render app.rb, SSL cert and keys, logstash forwarder config, start logstash
forwarder, start sinatra app (foreman)
• Nginx – render nginx.conf (-onetime) and start confd to check and update conf every 10
minutes, start nginx, tail nginx logs

18. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.18
Confd – resource file (nginx)
[template]
keys = [ "app/server", "elasticsearch/host" ]
owner = "nginx"
mode = "0644"
src = "nginx.conf.tmpl"
dest = "/etc/nginx/sites-enabled/docker_dns.conf"
check_cmd = "/usr/sbin/nginx -t -c /etc/nginx/nginx.conf"
reload_cmd = "/usr/sbin/service nginx reload"

19. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.19
Confd – template (nginx)
upstream app {
{{ range $server := .app_server }}
server {{ $server.Value }};
{{ end }}
}
…
upstream elasticsearch {
server {{ .elasticsearch_host }}:9200;
keepalive 15;
}

20. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.20
Looking at etcd
ubuntu@dod-01:~$ etcdctl ls --recursive
/elasticsearch
/elasticsearch/host
/elasticsearch/hostpublic
/logstash
/logstash/ssl_certificate
/logstash/ssl_private_key
/logstash/host
/app
/app/title
/app/server
/app/server/5000
/app/server/5001
/app/server/5002
/app/server/5003
ubuntu@dod-01:~$ etcdctl get /app/server/5000
10.0.0.58:5000

21. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.21
The CoreOS DNA Cluster + ELK Stack

22. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.22
ELK Stack + Sinatra Worker Agents (ELK - Elasticsearch, Logstash, Kibana)
Example Application – Application Architecture
HTT
P
Logstash
Service
HTT
P
Nginx
Port: 80
Key
Docker
Container
HTTP
Logstas
hPublic
Internet
Worker “@5001”
Worker “@5002”
Worker “@5003”
…
Worker
“@5000”Sinatra Service:
“Hello World”
Logstash
Agent
H
T
T
P
etcd
/logstash
/logstash/host
…
/app/server/5000
/app/server/5001
…
/elasticsearch/host
…
etcd
(federated)
Elasticsearc
hKibana
Kopf
Plugins:

23. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Demohttps://youtu.be/pRtQ0AXYe6M

24. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Questions, Comments &
Feedback?
Dod Ansible Repository https://github.com/HPATG/DeCore
Sample app code https://github.com/HPATG/sample_a
pp
Marcel De Graaf’s blog post http://marceldegraaf.net/2014/05/05/
coreos-follow-up-sinatra-logstash-
elasticsearch-kibana.html

25. © Copyright 2014 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Thank You
Advanced Technology Group
Eric Gustafson gustafson@hp.com
Yazz Atlas yazz.atlas@hp.com
Patrick Galbraith patg@hp.com
Special Thanks
Marcel De Graaf http://marceldegraaf.net/
Kelsey Hightower https://github.com/kelseyhightower