This presentation covers different Load balancing options with Docker. Each option is illustrated with a demo.

1. DOCKER NETWORKING
TIPS
Load Balance Options
Presenter’s Name: Sreenivas Makam
Associated Youtube video:
https://youtu.be/aQmPqrHleJU

2. About me
 Senior Engineering Manager at Cisco Systems Data Center group
 Author of “Mastering CoreOS” https://www.packtpub.com/networking-
and-servers/mastering-coreos/ )
 Docker Captain(https://www.docker.com/community/docker-captains )
 Blog: https://sreeninet.wordpress.com/
 Projects: https://github.com/smakam
 LinkedIn: https://in.linkedin.com/in/sreenivasmakam
 Twitter: @srmakam

3. What is Service Discovery?
 Allows micro services running as containers to discover each
other automatically.
 Components of Service Discovery
 Health check – Identify healthy service
 DNS – Maintain service name to IP mapping
 Load balancer uses Service discovery database.
 Standalone Service discovery software examples – Consul, etcd

4. Service Discovery in Docker
 Service discovery is provided by DNS server available in Docker
engine.
 For unmanaged containers, container name resolves to
container IP. Alias names can be also be used.
 For services using service IP(endpoint mode=vip), service name
resolves to service IP which in turn forwards the request to
containers. In this case, ipvs based L4 load balancing is done.
 For services using direct DNS(endpoint mode=dnsrr), service
name directly resolves to container IP. In this case, DNS round
robin load balancing is done.
 Service Discovery is network scoped. Only containers in same
network can discover each other.

5. L4 Load balancer does load balancing based on L3 and L4 fields.
L7 Load balancer uses URL fields to load balance.
Load balancer also supports advanced features like SSL/TLS
termination, Content based routing, Access control and
authorization, Rewrites and redirects, sticky session
Example Load balancers are nginx, haproxy, traefik, ELB in AWS.
What is Load balancing?

6.  For unmanaged containers, load balancing is done using simple round robin
load balancing. Using aliases, a single alias can load balance to multiple
unmanaged containers .
 Docker takes care of load balancing internal services to the containers
associated with the services.
 For services using service IP(endpoint mode=vip), ipvs and iptables are used to
load balance. This provides L4 based load balancing. Ipvs is Linux kernel load
balancing feature.
 For services using direct DNS(endpoint mode=dnsrr), DNS round robin
balancing is used.
 For services exposed externally, Docker uses routing mesh to expose the service
on all Swarm nodes. Routing mesh uses “ingress” network to connect all nodes.
 For HTTP based load balancing, HRM(HTTP Routing mesh) can be used. This is
supported only with Docker EE.
 Docker can also integrate with external load balancers like nginx, haproxy,
traefik as well as cloud load balancers like ELB.
Load balancing in Docker

7. Client
(smakam/myubuntu)
Web server
(instavote/vote)
Web server
(instavote/vote)
Swarm
LB
Service name
Container IP
Container IP
Internal Load balancer
Example: https://github.com/smakam/docker/tree/master/loadbalance/internal

8. Client
(smakam/myubuntu)
Service
name
DNS Service IP
IP tables +
IPVS
Web server
(instavote/vote)
Web server
(instavote/vote)
Internal Load balancer - Details
Example: https://github.com/smakam/docker/tree/master/loadbalance/internal

9. Ingress
Network
Web server
(instavote/vote)
Web server
(instavote/vote)
Swarm
LB
Service name
Container IP
Container IP
Host name/IP:
Port
Ingress Load balancer
Example: https://github.com/smakam/docker/tree/master/loadbalance/ingress

10. Sandbox IP
Host name/IP:
Port
Ingress sandbox IP tables +
IPVS
Web server
(instavote/vote)
Web server
(instavote/vote)
NAT
Ingress Load balancer - Details
Example: https://github.com/smakam/docker/tree/master/loadbalance/ingress

11. Nginx Proxy
LB
Web server
(instavote/vote)
Web server
(instavote/vote)
Swarm
LB
Service
name
Container IP
Container IPRedirect
Ingress +
Swarm LBHost name/IP:
Port
Proxy Load balancer
Example: https://github.com/smakam/docker/tree/master/loadbalance/proxy

12. Ingress +
Swarm LB
Web server
(nginx)
Web server
(instavote/vote)
Traefik/
UCP
LBRedirect
Host name/IP:
Port
Web server
(instavote/vote)
Web server
(nginx)
/web
/vote
“vote” service
“Web” service
L7 Load balancer
Example: https://github.com/smakam/docker/tree/master/loadbalance/traefik

13. References
 White paper on Docker networking
 HRM and UCP White paper
 Docker blogs by me
 Docker Networking – common
issues and troubleshooting techniques