8936: update comment on keepstore and go fmt

[arvados.git] / services / keepstore / keepstore.go

package main

import (
        "bytes"
        "flag"
        "fmt"
        "git.curoverse.com/arvados.git/sdk/go/keepclient"
        "io/ioutil"
        "log"
        "net"
        "net/http"
        "os"
        "os/signal"
        "strings"
        "syscall"
        "time"
)

// ======================
// Configuration settings
//
// TODO(twp): make all of these configurable via command line flags
// and/or configuration file settings.

// Default TCP address on which to listen for requests.
// Initialized by the --listen flag.
const DefaultAddr = ":25107"

// A Keep "block" is 64MB.
const BlockSize = 64 * 1024 * 1024

// A Keep volume must have at least MinFreeKilobytes available
// in order to permit writes.
const MinFreeKilobytes = BlockSize / 1024

// ProcMounts /proc/mounts
var ProcMounts = "/proc/mounts"

// enforcePermissions controls whether permission signatures
// should be enforced (affecting GET and DELETE requests).
// Initialized by the -enforce-permissions flag.
var enforcePermissions bool

// blobSignatureTTL is the time duration for which new permission
// signatures (returned by PUT requests) will be valid.
// Initialized by the -permission-ttl flag.
var blobSignatureTTL time.Duration

// dataManagerToken represents the API token used by the
// Data Manager, and is required on certain privileged operations.
// Initialized by the -data-manager-token-file flag.
var dataManagerToken string

// neverDelete can be used to prevent the DELETE handler from
// actually deleting anything.
var neverDelete = true

// trashLifetime is the time duration after a block is trashed
// during which it can be recovered using an /untrash request
// Use 10s or 10m or 10h to set as 10 seconds or minutes or hours respectively.
var trashLifetime time.Duration

// trashCheckInterval is the time duration at which the emptyTrash goroutine
// will check and delete expired trashed blocks. Default is one day.
// Use 10s or 10m or 10h to set as 10 seconds or minutes or hours respectively.
var trashCheckInterval time.Duration

var maxBuffers = 128
var bufs *bufferPool

// KeepError types.
//
type KeepError struct {
        HTTPCode int
        ErrMsg   string
}

var (
        BadRequestError     = &KeepError{400, "Bad Request"}
        UnauthorizedError   = &KeepError{401, "Unauthorized"}
        CollisionError      = &KeepError{500, "Collision"}
        RequestHashError    = &KeepError{422, "Hash mismatch in request"}
        PermissionError     = &KeepError{403, "Forbidden"}
        DiskHashError       = &KeepError{500, "Hash mismatch in stored data"}
        ExpiredError        = &KeepError{401, "Expired permission signature"}
        NotFoundError       = &KeepError{404, "Not Found"}
        GenericError        = &KeepError{500, "Fail"}
        FullError           = &KeepError{503, "Full"}
        SizeRequiredError   = &KeepError{411, "Missing Content-Length"}
        TooLongError        = &KeepError{413, "Block is too large"}
        MethodDisabledError = &KeepError{405, "Method disabled"}
        ErrNotImplemented   = &KeepError{500, "Unsupported configuration"}
)

func (e *KeepError) Error() string {
        return e.ErrMsg
}

// ========================
// Internal data structures
//
// These global variables are used by multiple parts of the
// program. They are good candidates for moving into their own
// packages.

// The Keep VolumeManager maintains a list of available volumes.
// Initialized by the --volumes flag (or by FindKeepVolumes).
var KeepVM VolumeManager

// The pull list manager and trash queue are threadsafe queues which
// support atomic update operations. The PullHandler and TrashHandler
// store results from Data Manager /pull and /trash requests here.
//
// See the Keep and Data Manager design documents for more details:
// https://arvados.org/projects/arvados/wiki/Keep_Design_Doc
// https://arvados.org/projects/arvados/wiki/Data_Manager_Design_Doc
//
var pullq *WorkQueue
var trashq *WorkQueue

type volumeSet []Volume

var (
        flagSerializeIO bool
        flagReadonly    bool
        volumes         volumeSet
)

func (vs *volumeSet) String() string {
        return fmt.Sprintf("%+v", (*vs)[:])
}

// TODO(twp): continue moving as much code as possible out of main
// so it can be effectively tested. Esp. handling and postprocessing
// of command line flags (identifying Keep volumes and initializing
// permission arguments).

func main() {
        log.Println("keepstore starting, pid", os.Getpid())
        defer log.Println("keepstore exiting, pid", os.Getpid())

        var (
                dataManagerTokenFile string
                listen               string
                blobSigningKeyFile   string
                permissionTTLSec     int
                pidfile              string
        )
        flag.StringVar(
                &dataManagerTokenFile,
                "data-manager-token-file",
                "",
                "File with the API token used by the Data Manager. All DELETE "+
                        "requests or GET /index requests must carry this token.")
        flag.BoolVar(
                &enforcePermissions,
                "enforce-permissions",
                false,
                "Enforce permission signatures on requests.")
        flag.StringVar(
                &listen,
                "listen",
                DefaultAddr,
                "Listening address, in the form \"host:port\". e.g., 10.0.1.24:8000. Omit the host part to listen on all interfaces.")
        flag.BoolVar(
                &neverDelete,
                "never-delete",
                true,
                "If true, nothing will be deleted. "+
                        "Warning: the relevant features in keepstore and data manager have not been extensively tested. "+
                        "You should leave this option alone unless you can afford to lose data.")
        flag.StringVar(
                &blobSigningKeyFile,
                "permission-key-file",
                "",
                "Synonym for -blob-signing-key-file.")
        flag.StringVar(
                &blobSigningKeyFile,
                "blob-signing-key-file",
                "",
                "File containing the secret key for generating and verifying "+
                        "blob permission signatures.")
        flag.IntVar(
                &permissionTTLSec,
                "permission-ttl",
                0,
                "Synonym for -blob-signature-ttl.")
        flag.IntVar(
                &permissionTTLSec,
                "blob-signature-ttl",
                int(time.Duration(2*7*24*time.Hour).Seconds()),
                "Lifetime of blob permission signatures. Modifying the ttl will invalidate all existing signatures"+
                        "See services/api/config/application.default.yml.")
        flag.BoolVar(
                &flagSerializeIO,
                "serialize",
                false,
                "Serialize read and write operations on the following volumes.")
        flag.BoolVar(
                &flagReadonly,
                "readonly",
                false,
                "Do not write, delete, or touch anything on the following volumes.")
        flag.StringVar(
                &pidfile,
                "pid",
                "",
                "Path to write pid file during startup. This file is kept open and locked with LOCK_EX until keepstore exits, so `fuser -k pidfile` is one way to shut down. Exit immediately if there is an error opening, locking, or writing the pid file.")
        flag.IntVar(
                &maxBuffers,
                "max-buffers",
                maxBuffers,
                fmt.Sprintf("Maximum RAM to use for data buffers, given in multiples of block size (%d MiB). When this limit is reached, HTTP requests requiring buffers (like GET and PUT) will wait for buffer space to be released.", BlockSize>>20))
        flag.DurationVar(
                &trashLifetime,
                "trash-lifetime",
                0*time.Second,
                "Time duration after a block is trashed during which it can be recovered using an /untrash request")
        flag.DurationVar(
                &trashCheckInterval,
                "trash-check-interval",
                24*time.Hour,
                "Time duration at which the emptyTrash goroutine will check and delete expired trashed blocks. Default is one day.")

        flag.Parse()

        if maxBuffers < 0 {
                log.Fatal("-max-buffers must be greater than zero.")
        }
        bufs = newBufferPool(maxBuffers, BlockSize)

        if pidfile != "" {
                f, err := os.OpenFile(pidfile, os.O_RDWR|os.O_CREATE, 0777)
                if err != nil {
                        log.Fatalf("open pidfile (%s): %s", pidfile, err)
                }
                err = syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
                if err != nil {
                        log.Fatalf("flock pidfile (%s): %s", pidfile, err)
                }
                err = f.Truncate(0)
                if err != nil {
                        log.Fatalf("truncate pidfile (%s): %s", pidfile, err)
                }
                _, err = fmt.Fprint(f, os.Getpid())
                if err != nil {
                        log.Fatalf("write pidfile (%s): %s", pidfile, err)
                }
                err = f.Sync()
                if err != nil {
                        log.Fatalf("sync pidfile (%s): %s", pidfile, err)
                }
                defer f.Close()
                defer os.Remove(pidfile)
        }

        if len(volumes) == 0 {
                if (&unixVolumeAdder{&volumes}).Discover() == 0 {
                        log.Fatal("No volumes found.")
                }
        }

        for _, v := range volumes {
                log.Printf("Using volume %v (writable=%v)", v, v.Writable())
        }

        // Initialize data manager token and permission key.
        // If these tokens are specified but cannot be read,
        // raise a fatal error.
        if dataManagerTokenFile != "" {
                if buf, err := ioutil.ReadFile(dataManagerTokenFile); err == nil {
                        dataManagerToken = strings.TrimSpace(string(buf))
                } else {
                        log.Fatalf("reading data manager token: %s\n", err)
                }
        }

        if neverDelete != true {
                log.Print("never-delete is not set. Warning: the relevant features in keepstore and data manager have not " +
                        "been extensively tested. You should leave this option alone unless you can afford to lose data.")
        }

        if blobSigningKeyFile != "" {
                if buf, err := ioutil.ReadFile(blobSigningKeyFile); err == nil {
                        PermissionSecret = bytes.TrimSpace(buf)
                } else {
                        log.Fatalf("reading permission key: %s\n", err)
                }
        }

        blobSignatureTTL = time.Duration(permissionTTLSec) * time.Second

        if PermissionSecret == nil {
                if enforcePermissions {
                        log.Fatal("-enforce-permissions requires a permission key")
                } else {
                        log.Println("Running without a PermissionSecret. Block locators " +
                                "returned by this server will not be signed, and will be rejected " +
                                "by a server that enforces permissions.")
                        log.Println("To fix this, use the -blob-signing-key-file flag " +
                                "to specify the file containing the permission key.")
                }
        }

        // Start a round-robin VolumeManager with the volumes we have found.
        KeepVM = MakeRRVolumeManager(volumes)

        // Tell the built-in HTTP server to direct all requests to the REST router.
        loggingRouter := MakeLoggingRESTRouter()
        http.HandleFunc("/", func(resp http.ResponseWriter, req *http.Request) {
                loggingRouter.ServeHTTP(resp, req)
        })

        // Set up a TCP listener.
        listener, err := net.Listen("tcp", listen)
        if err != nil {
                log.Fatal(err)
        }

        // Initialize Pull queue and worker
        keepClient := &keepclient.KeepClient{
                Arvados:       nil,
                Want_replicas: 1,
                Client:        &http.Client{},
        }

        // Initialize the pullq and worker
        pullq = NewWorkQueue()
        go RunPullWorker(pullq, keepClient)

        // Initialize the trashq and worker
        trashq = NewWorkQueue()
        go RunTrashWorker(trashq)

        // Start emptyTrash goroutine
        doneEmptyingTrash := make(chan bool)
        go emptyTrash(doneEmptyingTrash, trashCheckInterval)

        // Shut down the server gracefully (by closing the listener)
        // if SIGTERM is received.
        term := make(chan os.Signal, 1)
        go func(sig <-chan os.Signal) {
                s := <-sig
                log.Println("caught signal:", s)
                doneEmptyingTrash <- true
                listener.Close()
        }(term)
        signal.Notify(term, syscall.SIGTERM)
        signal.Notify(term, syscall.SIGINT)

        log.Println("listening at", listen)
        srv := &http.Server{Addr: listen}
        srv.Serve(listener)
}

// At every trashCheckInterval tick, invoke EmptyTrash on all volumes.
func emptyTrash(doneEmptyingTrash chan bool, trashCheckInterval time.Duration) {
        ticker := time.NewTicker(trashCheckInterval)

        for {
                select {
                case <-ticker.C:
                        for _, v := range volumes {
                                if v.Writable() {
                                        v.EmptyTrash()
                                }
                        }
                case <-doneEmptyingTrash:
                        ticker.Stop()
                        return
                }
        }
}