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ovs.go
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ovs.go
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package ovs
import (
"bytes"
"fmt"
"strconv"
"strings"
"github.com/golang/glog"
utilversion "k8s.io/kubernetes/pkg/util/version"
"k8s.io/utils/exec"
)
// Interface represents an interface to OVS
type Interface interface {
// AddBridge creates the bridge associated with the interface, optionally setting
// properties on it (as with "ovs-vsctl set Bridge ..."). If the bridge already
// exists this errors.
AddBridge(properties ...string) error
// DeleteBridge deletes the bridge associated with the interface. The boolean
// that can be passed determines if a bridge not existing is an error. Passing
// true will delete bridge --if-exists, passing false will error if the bridge
// does not exist.
DeleteBridge(ifExists bool) error
// AddPort adds an interface to the bridge, requesting the indicated port
// number, and optionally setting properties on it (as with "ovs-vsctl set
// Interface ..."). Returns the allocated port number (or an error).
AddPort(port string, ofportRequest int, properties ...string) (int, error)
// DeletePort removes an interface from the bridge. (It is not an
// error if the interface is not currently a bridge port.)
DeletePort(port string) error
// GetOFPort returns the OpenFlow port number of a given network interface
// attached to a bridge.
GetOFPort(port string) (int, error)
// SetFrags sets the fragmented-packet-handling mode (as with
// "ovs-ofctl set-frags")
SetFrags(mode string) error
// Create creates a record in the OVS database, as with "ovs-vsctl create" and
// returns the UUID of the newly-created item.
// NOTE: This only works for QoS; for all other tables the created object will
// immediately be garbage-collected; we'd need an API that calls "create" and "set"
// in the same "ovs-vsctl" call.
Create(table string, values ...string) (string, error)
// Destroy deletes the indicated record in the OVS database. It is not an error if
// the record does not exist
Destroy(table, record string) error
// Get gets the indicated value from the OVS database. For multi-valued or
// map-valued columns, the data is returned in the same format as "ovs-vsctl get".
Get(table, record, column string) (string, error)
// Set sets one or more columns on a record in the OVS database, as with
// "ovs-vsctl set"
Set(table, record string, values ...string) error
// Clear unsets the indicated columns in the OVS database. It is not an error if
// the value is already unset
Clear(table, record string, columns ...string) error
// Find finds records in the OVS database that match the given condition.
// It returns the value of the given column of matching records.
Find(table, column, condition string) ([]string, error)
// DumpFlows dumps the flow table for the bridge and returns it as an array of
// strings, one per flow. If flow is not "" then it describes the flows to dump.
DumpFlows(flow string, args ...interface{}) ([]string, error)
// NewTransaction begins a new OVS transaction.
NewTransaction() Transaction
}
// Transaction manages a single set of OVS flow modifications
type Transaction interface {
// AddFlow prepares adding a flow to the bridge.
// Given flow is cached but not executed at this time.
// The arguments are passed to fmt.Sprintf().
AddFlow(flow string, args ...interface{})
// DeleteFlows prepares deleting all matching flows from the bridge.
// Given flow is cached but not executed at this time.
// The arguments are passed to fmt.Sprintf().
DeleteFlows(flow string, args ...interface{})
// Commit executes all cached flows as a single atomic transaction and
// returns any error that occurred during the transaction.
Commit() error
}
const (
OVS_OFCTL = "ovs-ofctl"
OVS_VSCTL = "ovs-vsctl"
)
// ovsExec implements ovs.Interface via calls to ovs-ofctl and ovs-vsctl
type ovsExec struct {
execer exec.Interface
bridge string
}
// New returns a new ovs.Interface
func New(execer exec.Interface, bridge string, minVersion string) (Interface, error) {
if _, err := execer.LookPath(OVS_OFCTL); err != nil {
return nil, fmt.Errorf("OVS is not installed")
}
if _, err := execer.LookPath(OVS_VSCTL); err != nil {
return nil, fmt.Errorf("OVS is not installed")
}
ovsif := &ovsExec{execer: execer, bridge: bridge}
if minVersion != "" {
minVer := utilversion.MustParseGeneric(minVersion)
out, err := ovsif.exec(OVS_VSCTL, "--version")
if err != nil {
return nil, fmt.Errorf("could not check OVS version is %s or higher", minVersion)
}
// First output line should end with version
lines := strings.Split(out, "\n")
spc := strings.LastIndex(lines[0], " ")
instVer, err := utilversion.ParseGeneric(lines[0][spc+1:])
if err != nil {
return nil, fmt.Errorf("could not find OVS version in %q", lines[0])
}
if !instVer.AtLeast(minVer) {
return nil, fmt.Errorf("found OVS %v, need %s or later", instVer, minVersion)
}
}
return ovsif, nil
}
func (ovsif *ovsExec) execWithStdin(cmd string, stdinArgs []string, args ...string) (string, error) {
switch cmd {
case OVS_OFCTL:
args = append([]string{"-O", "OpenFlow13"}, args...)
case OVS_VSCTL:
args = append([]string{"--timeout=30"}, args...)
}
kcmd := ovsif.execer.Command(cmd, args...)
if stdinArgs != nil {
stdinString := strings.Join(stdinArgs, "\n")
stdin := bytes.NewBufferString(stdinString)
kcmd.SetStdin(stdin)
glog.V(4).Infof("Executing: %s %s <<\n%s", cmd, strings.Join(args, " "), stdinString)
} else {
glog.V(4).Infof("Executing: %s %s", cmd, strings.Join(args, " "))
}
output, err := kcmd.CombinedOutput()
if err != nil {
glog.V(2).Infof("Error executing %s: %s", cmd, string(output))
return "", err
}
outStr := string(output)
if outStr != "" {
// If output is a single line, strip the trailing newline
nl := strings.Index(outStr, "\n")
if nl == len(outStr)-1 {
outStr = outStr[:nl]
}
}
return outStr, nil
}
func (ovsif *ovsExec) exec(cmd string, args ...string) (string, error) {
return ovsif.execWithStdin(cmd, nil, args...)
}
func (ovsif *ovsExec) AddBridge(properties ...string) error {
args := []string{"add-br", ovsif.bridge}
if len(properties) > 0 {
args = append(args, "--", "set", "Bridge", ovsif.bridge)
args = append(args, properties...)
}
_, err := ovsif.exec(OVS_VSCTL, args...)
return err
}
func (ovsif *ovsExec) DeleteBridge(ifExists bool) error {
args := []string{"del-br", ovsif.bridge}
if ifExists {
args = append([]string{"--if-exists"}, args...)
}
_, err := ovsif.exec(OVS_VSCTL, args...)
return err
}
func (ovsif *ovsExec) GetOFPort(port string) (int, error) {
ofportStr, err := ovsif.exec(OVS_VSCTL, "get", "Interface", port, "ofport")
if err != nil {
return -1, fmt.Errorf("failed to get OVS port for %s: %v", port, err)
}
ofport, err := strconv.Atoi(ofportStr)
if err != nil {
return -1, fmt.Errorf("could not parse allocated ofport %q: %v", ofportStr, err)
}
if ofport == -1 {
errStr, err := ovsif.exec(OVS_VSCTL, "get", "Interface", port, "error")
if err != nil || errStr == "" {
errStr = "unknown error"
}
return -1, fmt.Errorf("error on port %s: %s", port, errStr)
}
return ofport, nil
}
func (ovsif *ovsExec) AddPort(port string, ofportRequest int, properties ...string) (int, error) {
args := []string{"--may-exist", "add-port", ovsif.bridge, port}
if ofportRequest > 0 || len(properties) > 0 {
args = append(args, "--", "set", "Interface", port)
if ofportRequest > 0 {
args = append(args, fmt.Sprintf("ofport_request=%d", ofportRequest))
}
if len(properties) > 0 {
args = append(args, properties...)
}
}
_, err := ovsif.exec(OVS_VSCTL, args...)
if err != nil {
return -1, err
}
ofport, err := ovsif.GetOFPort(port)
if err != nil {
return -1, err
}
if ofportRequest > 0 && ofportRequest != ofport {
return -1, fmt.Errorf("allocated ofport (%d) did not match request (%d)", ofport, ofportRequest)
}
return ofport, nil
}
func (ovsif *ovsExec) DeletePort(port string) error {
_, err := ovsif.exec(OVS_VSCTL, "--if-exists", "del-port", ovsif.bridge, port)
return err
}
func (ovsif *ovsExec) SetFrags(mode string) error {
_, err := ovsif.exec(OVS_OFCTL, "set-frags", ovsif.bridge, mode)
return err
}
func (ovsif *ovsExec) Create(table string, values ...string) (string, error) {
args := append([]string{"create", table}, values...)
return ovsif.exec(OVS_VSCTL, args...)
}
func (ovsif *ovsExec) Destroy(table, record string) error {
_, err := ovsif.exec(OVS_VSCTL, "--if-exists", "destroy", table, record)
return err
}
func (ovsif *ovsExec) Get(table, record, column string) (string, error) {
return ovsif.exec(OVS_VSCTL, "get", table, record, column)
}
func (ovsif *ovsExec) Set(table, record string, values ...string) error {
args := append([]string{"set", table, record}, values...)
_, err := ovsif.exec(OVS_VSCTL, args...)
return err
}
// Returns the given column of records that match the condition
func (ovsif *ovsExec) Find(table, column, condition string) ([]string, error) {
output, err := ovsif.exec(OVS_VSCTL, "--no-heading", "--columns="+column, "find", table, condition)
if err != nil {
return nil, err
}
values := strings.Split(output, "\n\n")
// We want "bare" values for strings, but we can't pass --bare to ovs-vsctl because
// it breaks more complicated types. So try passing each value through Unquote();
// if it fails, that means the value wasn't a quoted string, so use it as-is.
for i, val := range values {
if unquoted, err := strconv.Unquote(val); err == nil {
values[i] = unquoted
}
}
return values, nil
}
func (ovsif *ovsExec) Clear(table, record string, columns ...string) error {
args := append([]string{"--if-exists", "clear", table, record}, columns...)
_, err := ovsif.exec(OVS_VSCTL, args...)
return err
}
func (ovsif *ovsExec) DumpFlows(flow string, args ...interface{}) ([]string, error) {
if len(args) > 0 {
flow = fmt.Sprintf(flow, args...)
}
out, err := ovsif.exec(OVS_OFCTL, "dump-flows", ovsif.bridge, flow)
if err != nil {
return nil, err
}
lines := strings.Split(out, "\n")
flows := make([]string, 0, len(lines))
for _, line := range lines {
if strings.Contains(line, "cookie=") {
flows = append(flows, line)
}
}
return flows, nil
}
func (ovsif *ovsExec) NewTransaction() Transaction {
return &ovsExecTx{ovsif: ovsif, flows: []string{}}
}
// bundle executes all given flows as a single atomic transaction
func (ovsif *ovsExec) bundle(flows []string) error {
if len(flows) == 0 {
return nil
}
_, err := ovsif.execWithStdin(OVS_OFCTL, flows, "bundle", ovsif.bridge, "-")
return err
}
// ovsExecTx implements ovs.Transaction and maintains current flow context
type ovsExecTx struct {
ovsif *ovsExec
flows []string
}
func (tx *ovsExecTx) AddFlow(flow string, args ...interface{}) {
if len(args) > 0 {
flow = fmt.Sprintf(flow, args...)
}
tx.flows = append(tx.flows, fmt.Sprintf("flow add %s", flow))
}
func (tx *ovsExecTx) DeleteFlows(flow string, args ...interface{}) {
if len(args) > 0 {
flow = fmt.Sprintf(flow, args...)
}
tx.flows = append(tx.flows, fmt.Sprintf("flow delete %s", flow))
}
func (tx *ovsExecTx) Commit() error {
err := tx.ovsif.bundle(tx.flows)
// Reset flow context
tx.flows = []string{}
return err
}