package main import ( "encoding/json" "flag" "io/ioutil" "log" "os" "os/signal" "syscall" "time" "git.curoverse.com/arvados.git/sdk/go/arvados" ) // Config specifies site configuration, like API credentials and the // choice of which servers are to be balanced. // // Config is loaded from a JSON config file (see usage()). type Config struct { // Arvados API endpoint and credentials. Client arvados.Client // List of service types (e.g., "disk") to balance. KeepServiceTypes []string KeepServiceList arvados.KeepServiceList // How often to check RunPeriod arvados.Duration // Number of collections to request in each API call CollectionBatchSize int // Max collections to buffer in memory (bigger values consume // more memory, but can reduce store-and-forward latency when // fetching pages) CollectionBuffers int } // RunOptions controls runtime behavior. The flags/options that belong // here are the ones that are useful for interactive use. For example, // "CommitTrash" is a runtime option rather than a config item because // it invokes a troubleshooting feature rather than expressing how // balancing is meant to be done at a given site. // // RunOptions fields are controlled by command line flags. type RunOptions struct { Once bool CommitPulls bool CommitTrash bool Logger *log.Logger Dumper *log.Logger // SafeRendezvousState from the most recent balance operation, // or "" if unknown. If this changes from one run to the next, // we need to watch out for races. See // (*Balancer)ClearTrashLists. SafeRendezvousState string } var debugf = func(string, ...interface{}) {} func main() { var config Config var runOptions RunOptions configPath := flag.String("config", "", "`path` of json configuration file") serviceListPath := flag.String("config.KeepServiceList", "", "`path` of json file with list of keep services to balance, as given by \"arv keep_service list\" "+ "(default: config[\"KeepServiceList\"], or if none given, get all available services and filter by config[\"KeepServiceTypes\"])") flag.BoolVar(&runOptions.Once, "once", false, "balance once and then exit") flag.BoolVar(&runOptions.CommitPulls, "commit-pulls", false, "send pull requests (make more replicas of blocks that are underreplicated or are not in optimal rendezvous probe order)") flag.BoolVar(&runOptions.CommitTrash, "commit-trash", false, "send trash requests (delete unreferenced old blocks, and excess replicas of overreplicated blocks)") dumpFlag := flag.Bool("dump", false, "dump details for each block to stdout") debugFlag := flag.Bool("debug", false, "enable debug messages") flag.Usage = usage flag.Parse() if *configPath == "" { log.Fatal("You must specify a config file (see `keep-balance -help`)") } mustReadJSON(&config, *configPath) if *serviceListPath != "" { mustReadJSON(&config.KeepServiceList, *serviceListPath) } if *debugFlag { debugf = log.Printf if j, err := json.Marshal(config); err != nil { log.Fatal(err) } else { log.Printf("config is %s", j) } } if *dumpFlag { runOptions.Dumper = log.New(os.Stdout, "", log.LstdFlags) } err := CheckConfig(config, runOptions) if err != nil { // (don't run) } else if runOptions.Once { _, err = (&Balancer{}).Run(config, runOptions) } else { err = RunForever(config, runOptions, nil) } if err != nil { log.Fatal(err) } } func mustReadJSON(dst interface{}, path string) { if buf, err := ioutil.ReadFile(path); err != nil { log.Fatalf("Reading %q: %v", path, err) } else if err = json.Unmarshal(buf, dst); err != nil { log.Fatalf("Decoding %q: %v", path, err) } } // RunForever runs forever, or (for testing purposes) until the given // stop channel is ready to receive. func RunForever(config Config, runOptions RunOptions, stop <-chan interface{}) error { if runOptions.Logger == nil { runOptions.Logger = log.New(os.Stderr, "", log.LstdFlags) } logger := runOptions.Logger ticker := time.NewTicker(time.Duration(config.RunPeriod)) // The unbuffered channel here means we only hear SIGUSR1 if // it arrives while we're waiting in select{}. sigUSR1 := make(chan os.Signal) signal.Notify(sigUSR1, syscall.SIGUSR1) logger.Printf("starting up: will scan every %v and on SIGUSR1", config.RunPeriod) for { if !runOptions.CommitPulls && !runOptions.CommitTrash { logger.Print("WARNING: Will scan periodically, but no changes will be committed.") logger.Print("======= Consider using -commit-pulls and -commit-trash flags.") } bal := &Balancer{} var err error runOptions, err = bal.Run(config, runOptions) if err != nil { logger.Print("run failed: ", err) } else { logger.Print("run succeeded") } select { case <-stop: signal.Stop(sigUSR1) return nil case <-ticker.C: logger.Print("timer went off") case <-sigUSR1: logger.Print("received SIGUSR1, resetting timer") // Reset the timer so we don't start the N+1st // run too soon after the Nth run is triggered // by SIGUSR1. ticker.Stop() ticker = time.NewTicker(time.Duration(config.RunPeriod)) } logger.Print("starting next run") } }