Nick Craig-Wood
560d3928d0
Previously, restoreState in NewDriver would restore volumes AND perform FUSE mounts synchronously before the Docker plugin socket was created. This caused two problems: 1. The monChan was created after restoreState, but mount() sends on monChan, causing a deadlock (send on nil channel blocks forever). 2. Even with the channel fix, slow or hanging mounts during state restore would block the server socket from being created, causing Docker to time out after ~13 seconds with "no such file or directory" for the plugin socket. Fix by: - Moving monChan creation and monitor goroutine start before restoreState - Splitting state restore into two phases: restoreState (metadata + filesystem setup only) and RestoreMounts (actual FUSE mounts) - Calling RestoreMounts asynchronously after the server starts listening - Performing mount restoration concurrently across volumes Fixes #9231
92 lines
2.9 KiB
Go
92 lines
2.9 KiB
Go
// Package docker serves a remote suitable for use with docker volume api
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package docker
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import (
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"context"
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_ "embed"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/spf13/cobra"
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"github.com/rclone/rclone/cmd"
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"github.com/rclone/rclone/cmd/mountlib"
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"github.com/rclone/rclone/cmd/serve"
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"github.com/rclone/rclone/fs/config/flags"
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"github.com/rclone/rclone/vfs"
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"github.com/rclone/rclone/vfs/vfsflags"
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)
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var (
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pluginName = "rclone"
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pluginScope = "local"
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baseDir = "/var/lib/docker-volumes/rclone"
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sockDir = "/run/docker/plugins" //lint:ignore U1000 unused when not building linux
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defSpecDir = "/etc/docker/plugins"
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stateFile = "docker-plugin.state"
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socketAddr = "" // TCP listening address or empty string for Unix socket
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socketGid = syscall.Getgid()
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canPersist = false // allows writing to config file
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forgetState = false
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noSpec = false
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)
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//go:embed docker.md
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var longHelp string
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// help returns the help string cleaned up to simplify appending
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func help() string {
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return strings.TrimSpace(longHelp) + "\n\n"
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}
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func init() {
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cmdFlags := Command.Flags()
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// Add command specific flags
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flags.StringVarP(cmdFlags, &baseDir, "base-dir", "", baseDir, "Base directory for volumes", "")
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flags.StringVarP(cmdFlags, &socketAddr, "socket-addr", "", socketAddr, "Address <host:port> or absolute path (default: /run/docker/plugins/rclone.sock)", "")
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flags.IntVarP(cmdFlags, &socketGid, "socket-gid", "", socketGid, "GID for unix socket (default: current process GID)", "")
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flags.BoolVarP(cmdFlags, &forgetState, "forget-state", "", forgetState, "Skip restoring previous state", "")
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flags.BoolVarP(cmdFlags, &noSpec, "no-spec", "", noSpec, "Do not write spec file", "")
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// Add common mount/vfs flags
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mountlib.AddFlags(cmdFlags)
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vfsflags.AddFlags(cmdFlags)
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// Register with parent command
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serve.Command.AddCommand(Command)
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}
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// Command definition for cobra
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var Command = &cobra.Command{
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Use: "docker",
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Short: `Serve any remote on docker's volume plugin API.`,
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Long: help() + strings.TrimSpace(vfs.Help()),
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Annotations: map[string]string{
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"versionIntroduced": "v1.56",
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"groups": "Filter",
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},
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Run: func(command *cobra.Command, args []string) {
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cmd.CheckArgs(0, 0, command, args)
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cmd.Run(false, false, command, func() error {
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ctx := context.Background()
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drv, err := NewDriver(ctx, baseDir, nil, nil, false, forgetState)
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if err != nil {
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return err
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}
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srv := NewServer(drv)
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// Restore mounts in background after the server starts
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// listening so Docker can communicate with the plugin
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// even if individual mounts are slow.
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go drv.RestoreMounts()
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if socketAddr == "" {
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// Listen on unix socket at /run/docker/plugins/<pluginName>.sock
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return srv.ServeUnix(pluginName, socketGid)
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}
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if filepath.IsAbs(socketAddr) {
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// Listen on unix socket at given path
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return srv.ServeUnix(socketAddr, socketGid)
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}
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return srv.ServeTCP(socketAddr, "", nil, noSpec)
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})
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},
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}
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