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package apiserverfront
import (
"context"
"encoding/json"
"errors"
"fmt"
"log/slog"
"net"
"os"
)
type Config struct {
Owner string
Address string
Control string
State string
FDStore bool
Log *slog.Logger
}
func (c Config) Validate() error {
if c.Owner == "" {
return errors.New("apiserverfront: --owner names whose front this is")
}
if c.Address == "" {
return errors.New("apiserverfront: no listen address (kcp-front-address)")
}
if c.State == "" {
return errors.New("apiserverfront: no state file (front-state)")
}
return CheckSocketPath(c.Control)
}
func StickyAddress(statePath, address string) string {
host, port, err := net.SplitHostPort(address)
if err != nil || port != "0" {
return address
}
b, err := os.ReadFile(statePath)
if err != nil {
return address
}
var st State
if json.Unmarshal(b, &st) != nil || st.Address == "" {
return address
}
h, p, err := net.SplitHostPort(st.Address)
if err != nil || h != host || p == "" || p == "0" {
return address
}
return st.Address
}
func Run(ctx context.Context, c Config) error {
if err := c.Validate(); err != nil {
return err
}
log := c.Log
if log == nil {
log = slog.Default()
}
log = log.With("component", "apiserver-front", "owner", c.Owner)
address := StickyAddress(c.State, c.Address)
getenv := os.Getenv
a, err := AcquireAll(address, c.FDStore, getenv)
if err != nil && address != c.Address {
log.Warn("the front's previous address is taken; it binds a new one", "previous", address, "err", err.Error())
a, err = AcquireAll(c.Address, c.FDStore, getenv)
}
if err != nil {
return err
}
store := ""
if c.FDStore {
store = a.Notify
}
f, err := New(a.Listener, Options{StatePath: c.State, Inherited: a.Inherited, Holds: a.Holds, FDStore: store, Log: log})
if err != nil {
a.Listener.Close()
for _, h := range a.Holds {
h.Close()
}
return err
}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
ctlErr := make(chan error, 1)
go func() {
ctlErr <- ServeControl(ctx, c.Control, f, func() {
st := f.Status()
log.Info("front listening", "address", st.Address, "control", c.Control, "backend", st.Backend,
"inherited", inherited, "fdStore", c.FDStore)
})
cancel()
}()
err = f.Serve(ctx)
cancel()
if cerr := <-ctlErr; cerr != nil && err == nil {
err = fmt.Errorf("apiserverfront: control socket: %w", cerr)
}
return err
}
