149 lines
3.9 KiB
Go
149 lines
3.9 KiB
Go
package agent
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import (
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"bytes"
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"crypto/md5"
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"fmt"
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"math"
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"os"
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"os/exec"
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"os/signal"
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osuser "os/user"
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"strconv"
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"time"
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"github.com/hashicorp/consul/types"
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"github.com/hashicorp/go-msgpack/codec"
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)
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const (
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// This scale factor means we will add a minute after we cross 128 nodes,
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// another at 256, another at 512, etc. By 8192 nodes, we will scale up
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// by a factor of 8.
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//
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// If you update this, you may need to adjust the tuning of
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// CoordinateUpdatePeriod and CoordinateUpdateMaxBatchSize.
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aeScaleThreshold = 128
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)
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// msgpackHandle is a shared handle for encoding/decoding of
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// messages
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var msgpackHandle = &codec.MsgpackHandle{
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RawToString: true,
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WriteExt: true,
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}
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// aeScale is used to scale the time interval at which anti-entropy updates take
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// place. It is used to prevent saturation as the cluster size grows.
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func aeScale(interval time.Duration, n int) time.Duration {
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// Don't scale until we cross the threshold
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if n <= aeScaleThreshold {
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return interval
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}
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multiplier := math.Ceil(math.Log2(float64(n))-math.Log2(aeScaleThreshold)) + 1.0
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return time.Duration(multiplier) * interval
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}
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// decodeMsgPack is used to decode a MsgPack encoded object
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func decodeMsgPack(buf []byte, out interface{}) error {
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return codec.NewDecoder(bytes.NewReader(buf), msgpackHandle).Decode(out)
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}
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// encodeMsgPack is used to encode an object with msgpack
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func encodeMsgPack(msg interface{}) ([]byte, error) {
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var buf bytes.Buffer
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err := codec.NewEncoder(&buf, msgpackHandle).Encode(msg)
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return buf.Bytes(), err
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}
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// stringHash returns a simple md5sum for a string.
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func stringHash(s string) string {
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return fmt.Sprintf("%x", md5.Sum([]byte(s)))
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}
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// checkIDHash returns a simple md5sum for a types.CheckID.
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func checkIDHash(checkID types.CheckID) string {
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return stringHash(string(checkID))
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}
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// setFilePermissions handles configuring ownership and permissions
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// settings on a given file. All permission/ownership settings are
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// optional. If no user or group is specified, the current user/group
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// will be used. Mode is optional, and has no default (the operation is
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// not performed if absent). User may be specified by name or ID, but
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// group may only be specified by ID.
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func setFilePermissions(path string, user, group, mode string) error {
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var err error
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uid, gid := os.Getuid(), os.Getgid()
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if user != "" {
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if uid, err = strconv.Atoi(user); err == nil {
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goto GROUP
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}
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// Try looking up the user by name
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if u, err := osuser.Lookup(user); err == nil {
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uid, _ = strconv.Atoi(u.Uid)
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goto GROUP
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}
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return fmt.Errorf("invalid user specified: %v", user)
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}
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GROUP:
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if group != "" {
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if gid, err = strconv.Atoi(group); err != nil {
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return fmt.Errorf("invalid group specified: %v", group)
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}
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}
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if err := os.Chown(path, uid, gid); err != nil {
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return fmt.Errorf("failed setting ownership to %d:%d on %q: %s",
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uid, gid, path, err)
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}
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if mode != "" {
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mode, err := strconv.ParseUint(mode, 8, 32)
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if err != nil {
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return fmt.Errorf("invalid mode specified: %v", mode)
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}
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if err := os.Chmod(path, os.FileMode(mode)); err != nil {
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return fmt.Errorf("failed setting permissions to %d on %q: %s",
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mode, path, err)
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}
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}
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return nil
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}
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// ExecSubprocess returns a command to execute a subprocess directly.
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func ExecSubprocess(args []string) (*exec.Cmd, error) {
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if len(args) == 0 {
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return nil, fmt.Errorf("need an executable to run")
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}
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return exec.Command(args[0], args[1:]...), nil
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}
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// ForwardSignals will fire up a goroutine to forward signals to the given
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// subprocess until the shutdown channel is closed.
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func ForwardSignals(cmd *exec.Cmd, logFn func(error), shutdownCh <-chan struct{}) {
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go func() {
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signalCh := make(chan os.Signal, 10)
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signal.Notify(signalCh, os.Interrupt, os.Kill)
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defer signal.Stop(signalCh)
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for {
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select {
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case sig := <-signalCh:
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if err := cmd.Process.Signal(sig); err != nil {
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logFn(fmt.Errorf("failed to send signal %q: %v", sig, err))
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}
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case <-shutdownCh:
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return
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}
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}
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}()
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}
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