github.com/juju/juju@v0.0.0-20240430160146-1752b71fcf00/worker/controlsocket/worker.go (about)

     1  // Copyright 2023 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  //go:build linux
     5  
     6  package controlsocket
     7  
     8  import (
     9  	"context"
    10  	"net"
    11  	"net/http"
    12  	"time"
    13  
    14  	"github.com/gorilla/mux"
    15  	"github.com/juju/errors"
    16  	"github.com/juju/worker/v3"
    17  	"gopkg.in/tomb.v2"
    18  
    19  	"github.com/juju/juju/juju/sockets"
    20  )
    21  
    22  // logger is here to stop the desire of creating a package level logger.
    23  // Don't do this, instead use the one passed as manifold config.
    24  type logger any
    25  
    26  var _ logger = struct{}{}
    27  
    28  // Logger represents the methods used by the worker to log information.
    29  type Logger interface {
    30  	Errorf(string, ...any)
    31  	Warningf(string, ...any)
    32  	Infof(string, ...any)
    33  	Debugf(string, ...any)
    34  	Tracef(string, ...any)
    35  }
    36  
    37  // Config represents configuration for the controlsocket worker.
    38  type Config struct {
    39  	State      State
    40  	Logger     Logger
    41  	SocketName string
    42  }
    43  
    44  // Validate returns an error if config cannot drive the Worker.
    45  func (config Config) Validate() error {
    46  	if config.State == nil {
    47  		return errors.NotValidf("nil State")
    48  	}
    49  	if config.Logger == nil {
    50  		return errors.NotValidf("nil Logger")
    51  	}
    52  	if config.SocketName == "" {
    53  		return errors.NotValidf("empty SocketName")
    54  	}
    55  	return nil
    56  }
    57  
    58  // Worker is a controlsocket worker.
    59  type Worker struct {
    60  	config   Config
    61  	tomb     tomb.Tomb
    62  	listener net.Listener
    63  }
    64  
    65  // NewWorker returns a controlsocket worker with the given config.
    66  func NewWorker(config Config) (worker.Worker, error) {
    67  	if err := config.Validate(); err != nil {
    68  		return nil, errors.Trace(err)
    69  	}
    70  
    71  	l, err := sockets.Listen(sockets.Socket{
    72  		Address: config.SocketName,
    73  		Network: "unix",
    74  	})
    75  	if err != nil {
    76  		return nil, errors.Annotate(err, "unable to listen on unix socket")
    77  	}
    78  	config.Logger.Debugf("controlsocket worker listening on socket %q", config.SocketName)
    79  
    80  	w := &Worker{
    81  		config:   config,
    82  		listener: l,
    83  	}
    84  	w.tomb.Go(w.run)
    85  	return w, nil
    86  }
    87  
    88  func (w *Worker) Kill() {
    89  	w.tomb.Kill(nil)
    90  }
    91  
    92  func (w *Worker) Wait() error {
    93  	return w.tomb.Wait()
    94  }
    95  
    96  // run listens on the control socket and handles requests.
    97  func (w *Worker) run() error {
    98  	router := mux.NewRouter()
    99  	w.registerHandlers(router)
   100  
   101  	srv := http.Server{Handler: router}
   102  	defer func() {
   103  		err := srv.Close()
   104  		if err != nil {
   105  			w.config.Logger.Warningf("error closing HTTP server: %v", err)
   106  		}
   107  	}()
   108  
   109  	go func() {
   110  		// Wait for the tomb to start dying and then shut the server down.
   111  		<-w.tomb.Dying()
   112  		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
   113  		defer cancel()
   114  		if err := srv.Shutdown(ctx); err != nil {
   115  			w.config.Logger.Warningf("error shutting down HTTP server: %v", err)
   116  		}
   117  	}()
   118  
   119  	w.config.Logger.Debugf("controlsocket worker now serving")
   120  	defer w.config.Logger.Debugf("controlsocket worker serving finished")
   121  	if err := srv.Serve(w.listener); err != http.ErrServerClosed {
   122  		return err
   123  	}
   124  	return nil
   125  }