Docker Networking Deep Dive
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This document provides an overview and agenda for a Docker networking deep dive presentation. The presentation covers key concepts in Docker networking including libnetwork, the Container Networking Model (CNM), multi-host networking capabilities, service discovery, load balancing, and new features in Docker 1.12 like routing mesh and secured control/data planes. The agenda demonstrates Docker networking use cases like default bridge networks, user-defined bridge networks, and overlay networks. It also covers networking drivers, Docker 1.12 swarm mode networking functionality, and how concepts like routing mesh and load balancing work.
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Docker Networking Deep Dive
- 1. Docker Networking Deep Dive @MadhuVenugopal online meetup 08/24/2016
- 2. • What is libnetwork • CNM • 1.12 Features • Multihost networking • Secured Control plane & Data plane • Service Discovery • Native Loadbalacing • Routing Mesh • Demo Agenda
- 3. Overview
- 4. It is not just a driver interface • Docker networking fabric • Defines Container Networking Model • Provides builtin IP address management • Provides native multi-host networking • Provides native Service Discovery and Load Balancing • Allows for extensions by the ecosystem via plugins What is libnetwork?
- 5. Design Philosophy • Users First: • Application Developers • IT/Network Ops • Plugin API Design • Batteries Included but Swappable
- 6. Docker Networking 1.7 1.8 1.9 1.10 1.11 - Libnetwork - CNM - Migrated Bridge, host, none drivers to CNM - Multihost Networking - Network Plugins - IPAM Plugins - Network UX/API Service Discovery (using /etc/hosts) Distributed DNS - Aliases - DNS Round Robin LB 1.12 - Load Balancing - Encrypted Control and data plane - Routing Mesh - Built-in Swarm-mode networking
- 7. Container Networking Model • Endpoint • Network • Sandbox • Drivers & Plugins https://github.com/docker/libnetwork/blob/master/docs/design.md
- 10. eth0 eth0 eth0 docker0 docker0 docker0 C1 eth0 eth0 C2 eth0 C3 C1 eth0 eth0 C2 eth0 C3 C1 eth0 eth0 C2 eth0 C3 ToR switch / Hypervisor switch / … iptables : NAT / port-mapping iptables : NAT / port-mapping iptables : NAT / port-mapping
- 12. Host1 : $ docker network create -d bridge -o com.docker.network.bridge.name=brnet brnet $ docker run --net=brnet -it busybox ifconfig eth0 brnet 172.18.0.1 ToR switch / Hypervisor switch / … eth0 C1 Host1 eth0 C2 eth0 C3 iptables : NAT / port-mapping eth0 brnet 172.18.0.1 eth0 C4 Host2 eth0 C5 eth0 C6 iptables : NAT / port-mapping eth0 brnet 172.18.0.1 eth0 C7 Host3 eth0 C8 eth0 C9 iptables : NAT / port-mapping Host2 : $ docker network create -d bridge -o com.docker.network.bridge.name=brnet brnet $ docker run --net=brnet -it busybox ifconfig Host3 : $ docker network create -d bridge -o com.docker.network.bridge.name=brnet brnet $ docker run --net=brnet -it busybox ifconfig
- 13. Use-case3 Bridge Network plumbed to underlay with built-in IPAM (no NAT / Port-mapping)
- 14. Host1 : $ docker network create -d bridge --subnet=192.168.57.0/24 --ip-range=192.168.57.32/28 --gateway=192.168.57.11 --aux-address DefaultGatewayIPv4=192.168.57.1 -o com.docker.network.bridge.name=brnet brnet $ brctl addif brnet eth2 $ docker run --net=brnet -it busybox ifconfig Host2 : $ docker network create -d bridge --subnet=192.168.57.0/24 --ip-range=192.168.57.64/28 --gateway=192.168.57.12 --aux-address DefaultGatewayIPv4=192.168.57.1 -o com.docker.network.bridge.name=brnet brnet $ brctl addif brnet eth2 $ docker run --net=brnet -it busybox ifconfig Host3 : $ docker network create -d bridge --subnet=192.168.57.0/24 --ip-range=192.168.57.128/28 --gateway=192.168.57.13 --aux-address DefaultGatewayIPv4=192.168.57.1 -o com.docker.network.bridge.name=brnet brnet $ brctl addif brnet eth2 $ docker run --net=brnet -it busybox ifconfig eth2 192.168.57.11 brnet 192.168.57.11 ToR switch / Hypervisor switch / Virtual-box host-only / … (Gateway : 192.168.57.1) eth0 C1 Host1 eth0 C2 eth0 C3 eth2 192.168.57.12 brnet 192.168.57.12 eth0 C4 eth0 C5 eth0 C6 eth2 192.168.57.13 brnet 192.168.57.13 eth0 C7 eth0 C8 eth0 C9 Host2 Host3
- 16. eth0 C1 eth1 eth1 eth1 ToR switch / Hypervisor switch / … docker0docker_gwbridge eth0 eth1 eth1 eth1 docker0docker_gwbridge eth0 eth1 eth1 eth1 docker0docker_gwbridge ov-net1 ov-net1 ov-net1 VXLAN-VNI 100 VXLAN-VNI 100 eth0 eth0 eth0 eth0 eth0 eth0 eth0 eth0 eth0 VXLAN-VNI 100 iptables : NAT / port-mapping iptables : NAT / port-mapping iptables : NAT / port-mapping Docker overlay networking C2 C3 C4 C5 C6 C7 C8 C9
- 17. Use-case5 Plumbed to underlay vlan with built-in IPAM macvlan driver (& experimental ipvlan) https://github.com/docker/docker/blob/master/experimental/vlan-networks.md
- 18. # vlan 10 (eth0.10) $ docker network create -d macvlan —subnet=10.1.10.0/24 — gateway=10.1.10.1 -o parent=eth0.10 mcvlan10 $ docker run --net=mcvlan10 -it --rm alpine /bin/sh # vlan 20 (eth0.20) $ docker network create -d macvlan —subnet=10.1.20.0/24 — gateway=10.1.20.1 -o parent=eth0.20 mcvlan20 $ docker run --net=mcvlan20 -it --rm alpine /bin/sh # vlan 30 (eth0.30) $ docker network create -d macvlan —subnet=10.1.30.0/24 — gateway=10.1.30.1 -o parent=eth0.30 mcvlan30 $ docker run --net=mcvlan30 -it --rm alpine /bin/sh
- 20. New features in 1.12 swarm mode CNM Routing Mesh Multi-host Networking without external k/v store Service Discovery Secure Data-Plane Secure Control-Plane Load Balancing • Cluster aware • De-centralized control plane • Highly scalable
- 21. Swarm-mode Multi-host networking Manager Network Create Orchestrator Allocator Scheduler Dispatcher Service Create Task Create Task Dispatch Task Dispatch Gossip Worker1 Worker2 Engine Libnetwork Engine Libnetwork • VXLAN based data path • No external key-value store • Central resource allocation • Improved performance • Highly scalable
- 22. • Gossip based protocol • Network scoped • Fast convergence • Secure by default • periodic key rotations • swarm native key-exchange • Gossips control messages • Routing-states • Service-discovery • Plugin-data • Highly scalable Secured network control plane Cluster Scope Gossip W1 W2 W3 W1 W5 W4 Network Scope Gossip Network Scope Gossip
- 23. • Available as an option during overlay network creation • Uses kernel IPSec modules • On-demand tunnel setup • Swarm native key-exchange • Periodic key rotations Secure dataplane Worker1 Worker2 Worker3 secure network secure network IPSec Tunnel IPSec Tunnel IPSec Tunnel secure network secure network non- secure network non- secure network Open UDP traffic
- 24. • Provided by embedded DNS • Highly available • Uses Network Control Plane to learn state • Can be used to discover both tasks and services Service Discovery engine DNS Server DNS Resolver DNS Resolver DNS requests
- 25. • Internal & Ingress load-balancing • Supports VIP & DNS-RR • Highly available • Uses Network Control Plane to learn state • Minimal Overhead Load balancer Task1 ServiceA Task2 ServiceA Task3 ServiceA Client1 Client2 VIP LB VIP LB
- 26. • Builtin routing mesh for edge routing • Worker nodes themselves participate in ingress routing mesh • All worker nodes accept connection requests on PublishedPort • Port translation happens at the worker node • Same internal load balancing mechanism used to load balance external requests Routing mesh External Loadbalancer (optional) Task1 ServiceA Task1 ServiceA Task1 ServiceA Worker1 Worker2 Ingress Network 8080 8080 VIP LB VIP LB 8080->80 8080->80
- 27. Routing Mesh • Operator reserves a swarm- wide ingress port (8080) for myapp • Every node listens on 8080 • Container-aware routing mesh can transparently reroute traffic from Worker3 to a node that is running container • Built in load balancing into the Engine • DNS-based service discovery Worker 1 :8080 Manager User accesses myapp.com:8080:8080 Worker 2 :8080 Worker 3 :8080 frontend frontend $ docker service create --replicas 3 --name frontend --network mynet --publish 8080:80/tcp frontend_image:latest frontend
- 28. Routing Mesh: Published Ports • Operator reserves a swarm- wide ingress port (8080) for myapp • Every node listens on 8080 • Container-aware routing mesh can transparently reroute traffic from Worker3 to a node that is running container • Built in load balancing into the Engine • DNS-based service discovery Worker 1 :8080 Manager User accesses myapp.com:8080:8080 Worker 2 :8080 Worker 3 :8080 frontend frontend $ docker service create --replicas 3 --name frontend --network mynet --publish 8080:80/tcp frontend_image:latest frontend
- 29. Deep Dive
- 30. Service , Port-Publish & Network iptables eth0 Host1 default_gwbridge ingress-sbox eth1 ingress-overlay-bridge Ingress- Network eth0 vxlan tunnel to host2 - vni-100vxlan tunnel to host3 - vni-100 eth0 Container-sbox eth1 eth2 mynet mynet-br vxlan tunnel to host2 - vni-101 docker service create —name=test —network=mynet -p 8080:80 —replicas=2 xxx iptables ipvs iptables ipvs Host1: 8080 DNS Resolver daemon embedded DNS server service -> VIP
- 31. Day in life of a packet - IPTables & IPVS
- 32. Day in life of a packet - Routing Mesh & Ingress LB iptables NAT table DOCKER-INGRESS DNAT : Published-Port -> ingress-sbox eth0 Host1 default_gwbridge ingress-sboxeth1 iptables NAT table PREROUTING Redirect -> service-port iptables MANGLE table PREROUTING MARK : Published-Port -> <fw-mark-id> IPVS Match <fw-mark-id> -> Masq {RR across container-IPs) ingress-overlay-bridge Ingress- Network eth0 iptables NAT table DOCKER-INGRESS DNAT : Published-Port -> ingress-sbox eth0 Host2 default_gwbridge ingress-sbox eth1 ingress-overlay-bridge eth0 vxlan tunnel with vni Ingress- Network eth0 Container-sbox (backs a task/ service) eth1
- 33. Day in life of a packet - Internal LB eth0 Host1 container-sbox (service1) eth1 iptables MANGLE table OUTPUT MARK : VIP -> <fw-mark-id> IPVS Match <fw-mark-id> -> Masq {RR across container-IPs) mynet-overlay-bridge mynet eth2 Host2 mynet-overlay-bridgevxlan tunnel with vni mynet eth2 Container-sbox (service2) Application looks up service2 (using embedded-DNS @ 127.0.0.11) DNS Resolver daemon embedded DNS server service2 -> VIP2 vxlan tunnel with vni
- 34. Thank you!