3 This set of packages provide the API for communication with VPP from Go. It consists of the following packages:
5 - [govpp](govpp.go): provides the entry point to govpp functionality
6 - [api](api/api.go): API for communication with govpp core using Go channels (without the need of importing the govpp core package itself),
7 - [core](core/): main functionality of the govpp, sends and receives the messages to/from VPP using the adapter, marshalls/unmarshalls them and forwards them between the client Go channels and the VPP,
8 - [adapter](adapter/): adapter between govpp core and the VPP, responsible for sending and receiving binary-encoded data via shared memory,
9 - [binapi-generator](cmd/binapi-generator/generator.go): Generator of Go structs out of the VPP binary API definitions in JSON format,
10 - [examples](examples/): example VPP management application that exercises the govpp API on real-world use-cases.
12 The design with separated govpp API package ([api](api/api.go)) and the govpp core package ([core](core/)) enables
13 plugin-based infrastructure, where one entity acts as a master responsible for talking with VPP (e.g. Agent
14 Core on the schema below) and multiple entities act as clients that are using the master for the communication with
15 VPP (Agent Plugins on the schema below). The clients can be built into standalone shared libraries without the need
16 of linking the govpp core and all its dependencies into them.
23 | Agent Core | +--------------+
24 | | +------+ govpp API |
25 | | | +--------------+
27 | | channels | +--------------+
28 | govpp core +------------+ | |
29 | | | | Agent Plugin |
30 +------+-------+ | | |
32 binary API | +------+ govpp API |
33 (shmem) | +--------------+
44 Generating Go bindings from the JSON files located in the `/usr/share/vpp/api/` directory
45 into the Go packages that will be created inside of the `bin_api` directory:
47 binapi-generator --input-dir=/usr/share/vpp/api/ --output-dir=bin_api
50 Usage of the generated bindings:
53 conn, _ := govpp.Connect()
54 defer conn.Disconnect()
56 ch, _ := conn.NewAPIChannel()
59 req := &acl.ACLAddReplace{
61 Tag: []byte("access list 1"),
65 SrcIPAddr: net.ParseIP("10.0.0.0").To4(),
67 DstIPAddr: net.ParseIP("192.168.1.0").To4(),
73 SrcIPAddr: net.ParseIP("8.8.8.8").To4(),
75 DstIPAddr: net.ParseIP("172.16.0.0").To4(),
81 reply := &acl.ACLAddReplaceReply{}
83 err := ch.SendRequest(req).ReceiveReply(reply)
87 The example above uses simple wrapper API over underlying go channels, see [example client](examples/cmd/simple-client/simple_client.go)
88 for more examples, including the example on how to use the Go channels directly.
91 ## Build & Installation Procedure
92 Govpp uses `vppapiclient` library from VPP codebase to communicate with VPP. To build govpp, vpp-dev package must be installed,
93 either [from packages](https://wiki.fd.io/view/VPP/Installing_VPP_binaries_from_packages) or
94 [from sources](https://wiki.fd.io/view/VPP/Build,_install,_and_test_images#Build_A_VPP_Package).
96 To build & install `vpp-dev` from sources:
98 git clone https://gerrit.fd.io/r/vpp
104 sudo dpkg -i vpp*.deb
107 To build & install all govpp binaries into your `$GOPATH`:
109 go get git.fd.io/govpp.git
110 cd $GOPATH/src/git.fd.io/govpp.git
116 ## Building Go bindings from VPP binary APIs
117 Once you have `binapi-generator` installed in your `$GOPATH`, you can use it to generate Go bindings from
118 VPP APis in JSON format. The JSON input can be specified as a single file (`input-file` argument), or
119 as a directory that will be scanned for all `.json` files (`input-dir`). The generated Go bindings will
120 be placed into `output-dir` (by default current working directory), where each Go package will be placed into
121 a separated directory, e.g.:
124 binapi-generator --input-file=examples/bin_api/acl.api.json --output-dir=examples/bin_api
125 binapi-generator --input-dir=examples/bin_api --output-dir=examples/bin_api
128 In Go, [go generate](https://blog.golang.org/generate) tool can be leveraged to ease the code generation
129 process. It allows to specify generator instructions in any one of the regular (non-generated) `.go` files
130 that are dependent on generated code using special comments, e.g. the one from
131 [example client](examples/cmd/simple-client/simple_client.go):
133 // go:generate binapi-generator --input-dir=bin_api --output-dir=bin_api
136 The comment must start at the beginning of the line and have no spaces between the `//` and the `go:generate`.
137 After that marker, the rest of the line specifies a command for `go generate` to run.
139 The `go generate` tool automatically traverses the code base, looks for the special comments in Go code and
140 invokes the code generation, e.g.:
144 Invokes all `go:generate` rules in all Go packages recursively.