mirror of https://github.com/k3s-io/k3s
92 lines
3.0 KiB
Markdown
92 lines
3.0 KiB
Markdown
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# netlink - netlink library for go #
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[](https://travis-ci.org/vishvananda/netlink) [](https://godoc.org/github.com/vishvananda/netlink)
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The netlink package provides a simple netlink library for go. Netlink
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is the interface a user-space program in linux uses to communicate with
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the kernel. It can be used to add and remove interfaces, set ip addresses
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and routes, and configure ipsec. Netlink communication requires elevated
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privileges, so in most cases this code needs to be run as root. Since
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low-level netlink messages are inscrutable at best, the library attempts
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to provide an api that is loosely modeled on the CLI provided by iproute2.
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Actions like `ip link add` will be accomplished via a similarly named
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function like AddLink(). This library began its life as a fork of the
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netlink functionality in
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[docker/libcontainer](https://github.com/docker/libcontainer) but was
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heavily rewritten to improve testability, performance, and to add new
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functionality like ipsec xfrm handling.
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## Local Build and Test ##
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You can use go get command:
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go get github.com/vishvananda/netlink
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Testing dependencies:
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go get github.com/vishvananda/netns
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Testing (requires root):
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sudo -E go test github.com/vishvananda/netlink
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## Examples ##
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Add a new bridge and add eth1 into it:
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```go
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package main
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import (
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"fmt"
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"github.com/vishvananda/netlink"
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)
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func main() {
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la := netlink.NewLinkAttrs()
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la.Name = "foo"
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mybridge := &netlink.Bridge{LinkAttrs: la}
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err := netlink.LinkAdd(mybridge)
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if err != nil {
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fmt.Printf("could not add %s: %v\n", la.Name, err)
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}
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eth1, _ := netlink.LinkByName("eth1")
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netlink.LinkSetMaster(eth1, mybridge)
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}
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```
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Note `NewLinkAttrs` constructor, it sets default values in structure. For now
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it sets only `TxQLen` to `-1`, so kernel will set default by itself. If you're
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using simple initialization(`LinkAttrs{Name: "foo"}`) `TxQLen` will be set to
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`0` unless you specify it like `LinkAttrs{Name: "foo", TxQLen: 1000}`.
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Add a new ip address to loopback:
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```go
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package main
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import (
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"github.com/vishvananda/netlink"
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)
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func main() {
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lo, _ := netlink.LinkByName("lo")
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addr, _ := netlink.ParseAddr("169.254.169.254/32")
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netlink.AddrAdd(lo, addr)
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}
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```
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## Future Work ##
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Many pieces of netlink are not yet fully supported in the high-level
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interface. Aspects of virtually all of the high-level objects don't exist.
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Many of the underlying primitives are there, so its a matter of putting
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the right fields into the high-level objects and making sure that they
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are serialized and deserialized correctly in the Add and List methods.
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There are also a few pieces of low level netlink functionality that still
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need to be implemented. Routing rules are not in place and some of the
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more advanced link types. Hopefully there is decent structure and testing
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in place to make these fairly straightforward to add.
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