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README
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Coil
Coil is a CNI plugin that automates IP address management (IPAM) and programs intra-node Pod routing for Kubernetes.
Coil is designed in favor of UNIX philosophy. It is not tightly integrated with routing daemons like BIRD. It does not implement Kubernetes Network Policies either.
Instead, users can choose their favorite routing daemons and/or network policy implementations for use with coil. There is a real-world example of using coil with MetalLB (for LoadBalancer) and Calico (for network policies) at github.com/cybozu-go/neco-apps.
Project Status: General Availability (GA)
Requirements
- Linux with routing software such as BIRD.
- Kubernetes Version
- 1.15, 1.16, 1.17
- Other versions are likely to work, but not tested.
- etcd: coil requires etcd v3 API, does not support v2.
Features
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IP address management (IPAM)
Coil dynamically allocates IP addresses to Pods.
Coil has a mechanism called address pool so that the administrator can control to assign special/global IP addresses only to some Pods.
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Address pools
An address pool is a pool of allocatable IP addresses. In addition to the default pool, users can define arbitrary address pools.
Pods in a specific Kubernetes namespace take their IP addresses from the address pool whose name matches the namespace if such a pool exists.
This way, only users who can create Pods in the namespace can use special/global IP addresses.
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Address block
Coil divides a large subnet into small fixed size blocks (e.g.
/27), and assign them to nodes. Nodes then allocate IP addresses to Pods from the assigned blocks. -
Intra-node Pod routing
Coil programs intra-node routing for Pods.
As to inter-node routing, coil publishes address blocks assigned to the node to an unused kernel routing table as described next.
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Publish address blocks to implement inter-node Pod routing
Coil registers address blocks assigned to a node with an unused kernel routing table. The default table ID is
119.The routing table can be referenced by other routing programs such as BIRD to implement inter-node routing.
An example BIRD configuration file that advertises address blocks via BGP is available at mtest/bird.conf.
Programs
This repository contains these programs:
coil: CNI plugin.coilctl: CLI tool to configure coil IPAM.coild: A background service to manage IP address.coil-controller: watches kubernetes resources for coil.coil-installer: installscoiland CNI configuration file.hypercoil: all-in-one binary just likehyperkube.
coil should be installed in /opt/cni/bin directory.
coilctl directly communicates with etcd.
Therefore it can be installed any host that can connect to etcd cluster.
coild and coil-installer should run as DaemonSet.
coil-controller should be deployed as Deployment.
Documentation
docs directory contains documents about designs and specifications.
mtest/bird.conf is an example configuration for BIRD to make it work with coil.
License
MIT
Documentation
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Index ¶
Constants ¶
const Version = "1.1.9"
Version represents the version of coil
Variables ¶
var ErrBlockNotFound = errors.New("block not found")
ErrBlockNotFound is returned when a target block does not exist.
Functions ¶
func ResolveEtcdEndpoints ¶
ResolveEtcdEndpoints checks if an endpoint begins with "@". If such an endpoint exists, it looks for Endpoints resource in "kube-system" namespace.
Suppose an endpoint is "@myetcd". If `kube-system/myetcd` Endpoints exists, then endpoints in cfg is replaced with those defined in the Endpoints resource.
Types ¶
type AddressPool ¶
AddressPool is a collection of subnets
func (AddressPool) MarshalJSON ¶
func (p AddressPool) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler
func (*AddressPool) UnmarshalJSON ¶
func (p *AddressPool) UnmarshalJSON(data []byte) error
UnmarshalJSON implements json.Unmarshaler
type BlockAssignment ¶
type BlockAssignment struct {
FreeList []*net.IPNet `json:"free"`
Nodes map[string][]*net.IPNet `json:"nodes"`
}
BlockAssignment holds address block assignment information for a subnet
func EmptyAssignment ¶
func EmptyAssignment(ipnet *net.IPNet, blockSize int) BlockAssignment
EmptyAssignment returns an empty block assignment for ipnet and blockSize.
func (*BlockAssignment) FindBlock ¶
func (ba *BlockAssignment) FindBlock(node string, block *net.IPNet) int
FindBlock returns index of target block
func (BlockAssignment) MarshalJSON ¶
func (ba BlockAssignment) MarshalJSON() ([]byte, error)
MarshalJSON implements Marshaler
func (*BlockAssignment) ReleaseBlock ¶
func (ba *BlockAssignment) ReleaseBlock(node string, block *net.IPNet) error
ReleaseBlock move target block to freeList from target node
func (*BlockAssignment) UnmarshalJSON ¶
func (ba *BlockAssignment) UnmarshalJSON(data []byte) error
UnmarshalJSON implements Unmarshaler
Source Files
Directories