ITQC/containernetworking-plugins
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Factor an API out into a module

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This takes some of the machinery from CNI and from the rkt networking
code, and turns it into a library that can be linked into go apps.

Included is an example command-line application that uses the library,
called `cnitool`.

Other headline changes:

 * Plugin exec'ing is factored out

The motivation here is to factor out the protocol for invoking
plugins. To that end, a generalisation of the code from api.go and
pkg/plugin/ipam.go goes into pkg/invoke/exec.go.

 * Move argument-handling and conf-loading into public API

The fact that the arguments get turned into an environment for the
plugin is incidental to the API; so, provide a way of supplying them
as a struct or saying "just use the same arguments as I got" (the
latter is for IPAM plugins).
This commit is contained in:
Michael Bridgen
2015-08-07 16:27:52 +01:00
parent 104e8b483e
commit 09a8148e36
9 changed files with 316 additions and 202 deletions
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76
invoke/args.go Normal file
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@ -0,0 +1,76 @@
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package invoke
import (
"os"
"strings"
)
type CNIArgs interface {
// For use with os/exec; i.e., return nil to inherit the
// environment from this process
AsEnv() []string
}
type inherited struct{}
var inheritArgsFromEnv inherited
func (_ *inherited) AsEnv() []string {
return nil
}
func ArgsFromEnv() CNIArgs {
return &inheritArgsFromEnv
}
type Args struct {
Command string
ContainerID string
NetNS string
PluginArgs [][2]string
PluginArgsStr string
IfName string
Path string
}
func (args *Args) AsEnv() []string {
env := os.Environ()
pluginArgsStr := args.PluginArgsStr
if pluginArgsStr == "" {
pluginArgsStr = stringify(args.PluginArgs)
}
env = append(env,
"CNI_COMMAND="+args.Command,
"CNI_CONTAINERID="+args.ContainerID,
"CNI_NETNS="+args.NetNS,
"CNI_ARGS="+pluginArgsStr,
"CNI_IFNAME="+args.IfName,
"CNI_PATH="+args.Path)
return env
}
// taken from rkt/networking/net_plugin.go
func stringify(pluginArgs [][2]string) string {
entries := make([]string, len(pluginArgs))
for i, kv := range pluginArgs {
entries[i] = strings.Join(kv[:], "=")
}
return strings.Join(entries, ";")
}

66
invoke/exec.go Normal file
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@ -0,0 +1,66 @@
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package invoke
import (
"bytes"
"encoding/json"
"fmt"
"os"
"os/exec"
"path/filepath"
"github.com/appc/cni/pkg/types"
)
func pluginErr(err error, output []byte) error {
if _, ok := err.(*exec.ExitError); ok {
emsg := types.Error{}
if perr := json.Unmarshal(output, &emsg); perr != nil {
return fmt.Errorf("netplugin failed but error parsing its diagnostic message %q: %v", string(output), perr)
}
details := ""
if emsg.Details != "" {
details = fmt.Sprintf("; %v", emsg.Details)
}
return fmt.Errorf("%v%v", emsg.Msg, details)
}
return err
}
func ExecPlugin(pluginPath string, netconf []byte, args CNIArgs) (*types.Result, error) {
if pluginPath == "" {
return nil, fmt.Errorf("could not find %q plugin", filepath.Base(pluginPath))
}
stdout := &bytes.Buffer{}
c := exec.Cmd{
Env: args.AsEnv(),
Path: pluginPath,
Args: []string{pluginPath},
Stdin: bytes.NewBuffer(netconf),
Stdout: stdout,
Stderr: os.Stderr,
}
if err := c.Run(); err != nil {
return nil, pluginErr(err, stdout.Bytes())
}
res := &types.Result{}
err := json.Unmarshal(stdout.Bytes(), res)
return res, err
}

37
invoke/find.go Normal file
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@ -0,0 +1,37 @@
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package invoke
import (
"os"
"path/filepath"
"strings"
)
func FindInPath(plugin string, path []string) string {
for _, p := range path {
fullname := filepath.Join(p, plugin)
if fi, err := os.Stat(fullname); err == nil && fi.Mode().IsRegular() {
return fullname
}
}
return ""
}
// Find returns the full path of the plugin by searching in CNI_PATH
func Find(plugin string) string {
paths := strings.Split(os.Getenv("CNI_PATH"), ":")
return FindInPath(plugin, paths)
}

35
ip/cidr.go
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@ -15,23 +15,10 @@
package ip
import (
"encoding/json"
"math/big"
"net"
)
// ParseCIDR takes a string like "10.2.3.1/24" and
// return IPNet with "10.2.3.1" and /24 mask
func ParseCIDR(s string) (*net.IPNet, error) {
ip, ipn, err := net.ParseCIDR(s)
if err != nil {
return nil, err
}
ipn.IP = ip
return ipn, nil
}
// NextIP returns IP incremented by 1
func NextIP(ip net.IP) net.IP {
i := ipToInt(ip)
@ -62,25 +49,3 @@ func Network(ipn *net.IPNet) *net.IPNet {
Mask: ipn.Mask,
}
}
// like net.IPNet but adds JSON marshalling and unmarshalling
type IPNet net.IPNet
func (n IPNet) MarshalJSON() ([]byte, error) {
return json.Marshal((*net.IPNet)(&n).String())
}
func (n *IPNet) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
tmp, err := ParseCIDR(s)
if err != nil {
return err
}
*n = IPNet(*tmp)
return nil
}

75
ipam/ipam.go Normal file
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@ -0,0 +1,75 @@
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ipam
import (
"fmt"
"os"
"github.com/appc/cni/pkg/invoke"
"github.com/appc/cni/pkg/ip"
"github.com/appc/cni/pkg/types"
"github.com/vishvananda/netlink"
)
func ExecAdd(plugin string, netconf []byte) (*types.Result, error) {
if os.Getenv("CNI_COMMAND") != "ADD" {
return nil, fmt.Errorf("CNI_COMMAND is not ADD")
}
return invoke.ExecPlugin(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
}
func ExecDel(plugin string, netconf []byte) error {
if os.Getenv("CNI_COMMAND") != "DEL" {
return fmt.Errorf("CNI_COMMAND is not DEL")
}
_, err := invoke.ExecPlugin(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
return err
}
// ConfigureIface takes the result of IPAM plugin and
// applies to the ifName interface
func ConfigureIface(ifName string, res *types.Result) error {
link, err := netlink.LinkByName(ifName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", ifName, err)
}
if err := netlink.LinkSetUp(link); err != nil {
return fmt.Errorf("failed to set %q UP: %v", ifName, err)
}
// TODO(eyakubovich): IPv6
addr := &netlink.Addr{IPNet: &res.IP4.IP, Label: ""}
if err = netlink.AddrAdd(link, addr); err != nil {
return fmt.Errorf("failed to add IP addr to %q: %v", ifName, err)
}
for _, r := range res.IP4.Routes {
gw := r.GW
if gw == nil {
gw = res.IP4.Gateway
}
if err = ip.AddRoute(&r.Dst, gw, link); err != nil {
// we skip over duplicate routes as we assume the first one wins
if !os.IsExist(err) {
return fmt.Errorf("failed to add route '%v via %v dev %v': %v", r.Dst, gw, ifName, err)
}
}
}
return nil
}

151
plugin/ipam.go
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@ -1,151 +0,0 @@
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package plugin
import (
"bytes"
"encoding/json"
"fmt"
"os"
"os/exec"
"path/filepath"
"strings"
"github.com/appc/cni/pkg/ip"
"github.com/vishvananda/netlink"
)
// Find returns the full path of the plugin by searching in CNI_PATH
func Find(plugin string) string {
paths := strings.Split(os.Getenv("CNI_PATH"), ":")
for _, p := range paths {
fullname := filepath.Join(p, plugin)
if fi, err := os.Stat(fullname); err == nil && fi.Mode().IsRegular() {
return fullname
}
}
return ""
}
func pluginErr(err error, output []byte) error {
if _, ok := err.(*exec.ExitError); ok {
emsg := Error{}
if perr := json.Unmarshal(output, &emsg); perr != nil {
return fmt.Errorf("netplugin failed but error parsing its diagnostic message %q: %v", string(output), perr)
}
details := ""
if emsg.Details != "" {
details = fmt.Sprintf("; %v", emsg.Details)
}
return fmt.Errorf("%v%v", emsg.Msg, details)
}
return err
}
// ExecAdd executes IPAM plugin, assuming CNI_COMMAND == ADD.
// Parses and returns resulting IPConfig
func ExecAdd(plugin string, netconf []byte) (*Result, error) {
if os.Getenv("CNI_COMMAND") != "ADD" {
return nil, fmt.Errorf("CNI_COMMAND is not ADD")
}
if plugin == "" {
return nil, fmt.Errorf(`name of IPAM plugin is missing. Please specify a "type" field in the "ipam" section`)
}
pluginPath := Find(plugin)
if pluginPath == "" {
return nil, fmt.Errorf("could not find %q IPAM plugin", plugin)
}
stdout := &bytes.Buffer{}
c := exec.Cmd{
Path: pluginPath,
Args: []string{pluginPath},
Stdin: bytes.NewBuffer(netconf),
Stdout: stdout,
Stderr: os.Stderr,
}
if err := c.Run(); err != nil {
return nil, pluginErr(err, stdout.Bytes())
}
res := &Result{}
err := json.Unmarshal(stdout.Bytes(), res)
return res, err
}
// ExecDel executes IPAM plugin, assuming CNI_COMMAND == DEL.
func ExecDel(plugin string, netconf []byte) error {
if os.Getenv("CNI_COMMAND") != "DEL" {
return fmt.Errorf("CNI_COMMAND is not DEL")
}
pluginPath := Find(plugin)
if pluginPath == "" {
return fmt.Errorf("could not find %q plugin", plugin)
}
stdout := &bytes.Buffer{}
c := exec.Cmd{
Path: pluginPath,
Args: []string{pluginPath},
Stdin: bytes.NewBuffer(netconf),
Stdout: stdout,
Stderr: os.Stderr,
}
if err := c.Run(); err != nil {
return pluginErr(err, stdout.Bytes())
}
return nil
}
// ConfigureIface takes the result of IPAM plugin and
// applies to the ifName interface
func ConfigureIface(ifName string, res *Result) error {
link, err := netlink.LinkByName(ifName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", ifName, err)
}
if err := netlink.LinkSetUp(link); err != nil {
return fmt.Errorf("failed to set %q UP: %v", ifName, err)
}
// TODO(eyakubovich): IPv6
addr := &netlink.Addr{IPNet: &res.IP4.IP, Label: ""}
if err = netlink.AddrAdd(link, addr); err != nil {
return fmt.Errorf("failed to add IP addr to %q: %v", ifName, err)
}
for _, r := range res.IP4.Routes {
gw := r.GW
if gw == nil {
gw = res.IP4.Gateway
}
if err = ip.AddRoute(&r.Dst, gw, link); err != nil {
// we skip over duplicate routes as we assume the first one wins
if !os.IsExist(err) {
return fmt.Errorf("failed to add route '%v via %v dev %v': %v", r.Dst, gw, ifName, err)
}
}
}
return nil
}

8
skel/skel.go
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@ -22,7 +22,7 @@ import (
"log"
"os"
"github.com/appc/cni/pkg/plugin"
"github.com/appc/cni/pkg/types"
)
// CmdArgs captures all the arguments passed in to the plugin
@ -93,7 +93,7 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
}
if err != nil {
if e, ok := err.(*plugin.Error); ok {
if e, ok := err.(*types.Error); ok {
// don't wrap Error in Error
dieErr(e)
}
@ -102,14 +102,14 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
}
func dieMsg(f string, args ...interface{}) {
e := &plugin.Error{
e := &types.Error{
Code: 100,
Msg: fmt.Sprintf(f, args...),
}
dieErr(e)
}
func dieErr(e *plugin.Error) {
func dieErr(e *types.Error) {
if err := e.Print(); err != nil {
log.Print("Error writing error JSON to stdout: ", err)
}

16
plugin/args.go → types/args.go
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@ -1,4 +1,18 @@
package plugin
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package types
import (
"encoding"

54
plugin/types.go → types/types.go
View File

@ -12,16 +12,48 @@
// See the License for the specific language governing permissions and
// limitations under the License.
package plugin
package types
import (
"encoding/json"
"net"
"os"
"github.com/appc/cni/pkg/ip"
)
// like net.IPNet but adds JSON marshalling and unmarshalling
type IPNet net.IPNet
// ParseCIDR takes a string like "10.2.3.1/24" and
// return IPNet with "10.2.3.1" and /24 mask
func ParseCIDR(s string) (*net.IPNet, error) {
ip, ipn, err := net.ParseCIDR(s)
if err != nil {
return nil, err
}
ipn.IP = ip
return ipn, nil
}
func (n IPNet) MarshalJSON() ([]byte, error) {
return json.Marshal((*net.IPNet)(&n).String())
}
func (n *IPNet) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
tmp, err := ParseCIDR(s)
if err != nil {
return err
}
*n = IPNet(*tmp)
return nil
}
// NetConf describes a network.
type NetConf struct {
Name string `json:"name,omitempty"`
@ -68,23 +100,23 @@ func (e *Error) Print() error {
}
// net.IPNet is not JSON (un)marshallable so this duality is needed
// for our custom ip.IPNet type
// for our custom IPNet type
// JSON (un)marshallable types
type ipConfig struct {
IP ip.IPNet `json:"ip"`
Gateway net.IP `json:"gateway,omitempty"`
Routes []Route `json:"routes,omitempty"`
IP IPNet `json:"ip"`
Gateway net.IP `json:"gateway,omitempty"`
Routes []Route `json:"routes,omitempty"`
}
type route struct {
Dst ip.IPNet `json:"dst"`
GW net.IP `json:"gw,omitempty"`
Dst IPNet `json:"dst"`
GW net.IP `json:"gw,omitempty"`
}
func (c *IPConfig) MarshalJSON() ([]byte, error) {
ipc := ipConfig{
IP: ip.IPNet(c.IP),
IP: IPNet(c.IP),
Gateway: c.Gateway,
Routes: c.Routes,
}
@ -117,7 +149,7 @@ func (r *Route) UnmarshalJSON(data []byte) error {
func (r *Route) MarshalJSON() ([]byte, error) {
rt := route{
Dst: ip.IPNet(r.Dst),
Dst: IPNet(r.Dst),
GW: r.GW,
}