open-vault/command/commands.go

package command

import (
	"os"
	"os/signal"
	"syscall"

	"github.com/hashicorp/vault/audit"
	"github.com/hashicorp/vault/builtin/plugin"
	"github.com/hashicorp/vault/sdk/logical"
	"github.com/hashicorp/vault/sdk/physical"
	"github.com/hashicorp/vault/sdk/version"
	"github.com/mitchellh/cli"

	/*
		The builtinplugins package is initialized here because it, in turn,
		initializes the database plugins.
		They register multiple database drivers for the "database/sql" package.
	*/
	_ "github.com/hashicorp/vault/helper/builtinplugins"

	auditFile "github.com/hashicorp/vault/builtin/audit/file"
	auditSocket "github.com/hashicorp/vault/builtin/audit/socket"
	auditSyslog "github.com/hashicorp/vault/builtin/audit/syslog"

	credAliCloud "github.com/hashicorp/vault-plugin-auth-alicloud"
	credCentrify "github.com/hashicorp/vault-plugin-auth-centrify"
	credCF "github.com/hashicorp/vault-plugin-auth-cf"
	credGcp "github.com/hashicorp/vault-plugin-auth-gcp/plugin"
	credOIDC "github.com/hashicorp/vault-plugin-auth-jwt"
	credKerb "github.com/hashicorp/vault-plugin-auth-kerberos"
	credOCI "github.com/hashicorp/vault-plugin-auth-oci"
	credAws "github.com/hashicorp/vault/builtin/credential/aws"
	credCert "github.com/hashicorp/vault/builtin/credential/cert"
	credGitHub "github.com/hashicorp/vault/builtin/credential/github"
	credLdap "github.com/hashicorp/vault/builtin/credential/ldap"
	credOkta "github.com/hashicorp/vault/builtin/credential/okta"
	credToken "github.com/hashicorp/vault/builtin/credential/token"
	credUserpass "github.com/hashicorp/vault/builtin/credential/userpass"

	logicalKv "github.com/hashicorp/vault-plugin-secrets-kv"
	logicalDb "github.com/hashicorp/vault/builtin/logical/database"

	physAerospike "github.com/hashicorp/vault/physical/aerospike"
	physAliCloudOSS "github.com/hashicorp/vault/physical/alicloudoss"
	physAzure "github.com/hashicorp/vault/physical/azure"
	physCassandra "github.com/hashicorp/vault/physical/cassandra"
	physCockroachDB "github.com/hashicorp/vault/physical/cockroachdb"
	physConsul "github.com/hashicorp/vault/physical/consul"
	physCouchDB "github.com/hashicorp/vault/physical/couchdb"
	physDynamoDB "github.com/hashicorp/vault/physical/dynamodb"
	physEtcd "github.com/hashicorp/vault/physical/etcd"
	physFoundationDB "github.com/hashicorp/vault/physical/foundationdb"
	physGCS "github.com/hashicorp/vault/physical/gcs"
	physManta "github.com/hashicorp/vault/physical/manta"
	physMSSQL "github.com/hashicorp/vault/physical/mssql"
	physMySQL "github.com/hashicorp/vault/physical/mysql"
	physOCI "github.com/hashicorp/vault/physical/oci"
	physPostgreSQL "github.com/hashicorp/vault/physical/postgresql"
	physRaft "github.com/hashicorp/vault/physical/raft"
	physS3 "github.com/hashicorp/vault/physical/s3"
	physSpanner "github.com/hashicorp/vault/physical/spanner"
	physSwift "github.com/hashicorp/vault/physical/swift"
	physZooKeeper "github.com/hashicorp/vault/physical/zookeeper"
	physFile "github.com/hashicorp/vault/sdk/physical/file"
	physInmem "github.com/hashicorp/vault/sdk/physical/inmem"

	sr "github.com/hashicorp/vault/serviceregistration"
	csr "github.com/hashicorp/vault/serviceregistration/consul"
	ksr "github.com/hashicorp/vault/serviceregistration/kubernetes"
)

const (
	// EnvVaultCLINoColor is an env var that toggles colored UI output.
	EnvVaultCLINoColor = `VAULT_CLI_NO_COLOR`
	// EnvVaultFormat is the output format
	EnvVaultFormat = `VAULT_FORMAT`

	// flagNameAddress is the flag used in the base command to read in the
	// address of the Vault server.
	flagNameAddress = "address"
	// flagnameCACert is the flag used in the base command to read in the CA
	// cert.
	flagNameCACert = "ca-cert"
	// flagnameCAPath is the flag used in the base command to read in the CA
	// cert path.
	flagNameCAPath = "ca-path"
	//flagNameClientCert is the flag used in the base command to read in the
	//client key
	flagNameClientKey = "client-key"
	//flagNameClientCert is the flag used in the base command to read in the
	//client cert
	flagNameClientCert = "client-cert"
	// flagNameTLSSkipVerify is the flag used in the base command to read in
	// the option to ignore TLS certificate verification.
	flagNameTLSSkipVerify = "tls-skip-verify"
	// flagTLSServerName is the flag used in the base command to read in
	// the TLS server name.
	flagTLSServerName = "tls-server-name"
	// flagNameAuditNonHMACRequestKeys is the flag name used for auth/secrets enable
	flagNameAuditNonHMACRequestKeys = "audit-non-hmac-request-keys"
	// flagNameAuditNonHMACResponseKeys is the flag name used for auth/secrets enable
	flagNameAuditNonHMACResponseKeys = "audit-non-hmac-response-keys"
	// flagNameDescription is the flag name used for tuning the secret and auth mount description parameter
	flagNameDescription = "description"
	// flagListingVisibility is the flag to toggle whether to show the mount in the UI-specific listing endpoint
	flagNameListingVisibility = "listing-visibility"
	// flagNamePassthroughRequestHeaders is the flag name used to set passthrough request headers to the backend
	flagNamePassthroughRequestHeaders = "passthrough-request-headers"
	// flagNameAllowedResponseHeaders is used to set allowed response headers from a plugin
	flagNameAllowedResponseHeaders = "allowed-response-headers"
	// flagNameTokenType is the flag name used to force a specific token type
	flagNameTokenType = "token-type"
)

var (
	auditBackends = map[string]audit.Factory{
		"file":   auditFile.Factory,
		"socket": auditSocket.Factory,
		"syslog": auditSyslog.Factory,
	}

	credentialBackends = map[string]logical.Factory{
		"plugin": plugin.Factory,
	}

	logicalBackends = map[string]logical.Factory{
		"plugin":   plugin.Factory,
		"database": logicalDb.Factory,
		// This is also available in the plugin catalog, but is here due to the need to
		// automatically mount it.
		"kv": logicalKv.Factory,
	}

	physicalBackends = map[string]physical.Factory{
		"aerospike":              physAerospike.NewAerospikeBackend,
		"alicloudoss":            physAliCloudOSS.NewAliCloudOSSBackend,
		"azure":                  physAzure.NewAzureBackend,
		"cassandra":              physCassandra.NewCassandraBackend,
		"cockroachdb":            physCockroachDB.NewCockroachDBBackend,
		"consul":                 physConsul.NewConsulBackend,
		"couchdb_transactional":  physCouchDB.NewTransactionalCouchDBBackend,
		"couchdb":                physCouchDB.NewCouchDBBackend,
		"dynamodb":               physDynamoDB.NewDynamoDBBackend,
		"etcd":                   physEtcd.NewEtcdBackend,
		"file_transactional":     physFile.NewTransactionalFileBackend,
		"file":                   physFile.NewFileBackend,
		"foundationdb":           physFoundationDB.NewFDBBackend,
		"gcs":                    physGCS.NewBackend,
		"inmem_ha":               physInmem.NewInmemHA,
		"inmem_transactional_ha": physInmem.NewTransactionalInmemHA,
		"inmem_transactional":    physInmem.NewTransactionalInmem,
		"inmem":                  physInmem.NewInmem,
		"manta":                  physManta.NewMantaBackend,
		"mssql":                  physMSSQL.NewMSSQLBackend,
		"mysql":                  physMySQL.NewMySQLBackend,
		"oci":                    physOCI.NewBackend,
		"postgresql":             physPostgreSQL.NewPostgreSQLBackend,
		"s3":                     physS3.NewS3Backend,
		"spanner":                physSpanner.NewBackend,
		"swift":                  physSwift.NewSwiftBackend,
		"raft":                   physRaft.NewRaftBackend,
		"zookeeper":              physZooKeeper.NewZooKeeperBackend,
	}

	serviceRegistrations = map[string]sr.Factory{
		"consul":     csr.NewServiceRegistration,
		"kubernetes": ksr.NewServiceRegistration,
	}
)

// Commands is the mapping of all the available commands.
var Commands map[string]cli.CommandFactory

func initCommands(ui, serverCmdUi cli.Ui, runOpts *RunOptions) {
	loginHandlers := map[string]LoginHandler{
		"alicloud": &credAliCloud.CLIHandler{},
		"aws":      &credAws.CLIHandler{},
		"centrify": &credCentrify.CLIHandler{},
		"cert":     &credCert.CLIHandler{},
		"cf":       &credCF.CLIHandler{},
		"gcp":      &credGcp.CLIHandler{},
		"github":   &credGitHub.CLIHandler{},
		"kerberos": &credKerb.CLIHandler{},
		"ldap":     &credLdap.CLIHandler{},
		"oci":      &credOCI.CLIHandler{},
		"oidc":     &credOIDC.CLIHandler{},
		"okta":     &credOkta.CLIHandler{},
		"pcf":      &credCF.CLIHandler{}, // Deprecated.
		"radius": &credUserpass.CLIHandler{
			DefaultMount: "radius",
		},
		"token": &credToken.CLIHandler{},
		"userpass": &credUserpass.CLIHandler{
			DefaultMount: "userpass",
		},
	}

	getBaseCommand := func() *BaseCommand {
		return &BaseCommand{
			UI:          ui,
			tokenHelper: runOpts.TokenHelper,
			flagAddress: runOpts.Address,
			client:      runOpts.Client,
		}
	}

	Commands = map[string]cli.CommandFactory{
		"agent": func() (cli.Command, error) {
			return &AgentCommand{
				BaseCommand: &BaseCommand{
					UI: serverCmdUi,
				},
				ShutdownCh: MakeShutdownCh(),
			}, nil
		},
		"audit": func() (cli.Command, error) {
			return &AuditCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"audit disable": func() (cli.Command, error) {
			return &AuditDisableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"audit enable": func() (cli.Command, error) {
			return &AuditEnableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"audit list": func() (cli.Command, error) {
			return &AuditListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"auth tune": func() (cli.Command, error) {
			return &AuthTuneCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"auth": func() (cli.Command, error) {
			return &AuthCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"auth disable": func() (cli.Command, error) {
			return &AuthDisableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"auth enable": func() (cli.Command, error) {
			return &AuthEnableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"auth help": func() (cli.Command, error) {
			return &AuthHelpCommand{
				BaseCommand: getBaseCommand(),
				Handlers:    loginHandlers,
			}, nil
		},
		"auth list": func() (cli.Command, error) {
			return &AuthListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"debug": func() (cli.Command, error) {
			return &DebugCommand{
				BaseCommand: getBaseCommand(),
				ShutdownCh:  MakeShutdownCh(),
			}, nil
		},
		"delete": func() (cli.Command, error) {
			return &DeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"lease": func() (cli.Command, error) {
			return &LeaseCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"lease renew": func() (cli.Command, error) {
			return &LeaseRenewCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"lease revoke": func() (cli.Command, error) {
			return &LeaseRevokeCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"list": func() (cli.Command, error) {
			return &ListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"login": func() (cli.Command, error) {
			return &LoginCommand{
				BaseCommand: getBaseCommand(),
				Handlers:    loginHandlers,
			}, nil
		},
		"namespace": func() (cli.Command, error) {
			return &NamespaceCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"namespace list": func() (cli.Command, error) {
			return &NamespaceListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"namespace lookup": func() (cli.Command, error) {
			return &NamespaceLookupCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"namespace create": func() (cli.Command, error) {
			return &NamespaceCreateCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"namespace delete": func() (cli.Command, error) {
			return &NamespaceDeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator": func() (cli.Command, error) {
			return &OperatorCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator generate-root": func() (cli.Command, error) {
			return &OperatorGenerateRootCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator init": func() (cli.Command, error) {
			return &OperatorInitCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator key-status": func() (cli.Command, error) {
			return &OperatorKeyStatusCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator migrate": func() (cli.Command, error) {
			return &OperatorMigrateCommand{
				BaseCommand:      getBaseCommand(),
				PhysicalBackends: physicalBackends,
				ShutdownCh:       MakeShutdownCh(),
			}, nil
		},
		"operator raft": func() (cli.Command, error) {
			return &OperatorRaftCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft list-peers": func() (cli.Command, error) {
			return &OperatorRaftListPeersCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft join": func() (cli.Command, error) {
			return &OperatorRaftJoinCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft remove-peer": func() (cli.Command, error) {
			return &OperatorRaftRemovePeerCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft snapshot": func() (cli.Command, error) {
			return &OperatorRaftSnapshotCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft snapshot restore": func() (cli.Command, error) {
			return &OperatorRaftSnapshotRestoreCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator raft snapshot save": func() (cli.Command, error) {
			return &OperatorRaftSnapshotSaveCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator rekey": func() (cli.Command, error) {
			return &OperatorRekeyCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator rotate": func() (cli.Command, error) {
			return &OperatorRotateCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator seal": func() (cli.Command, error) {
			return &OperatorSealCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator step-down": func() (cli.Command, error) {
			return &OperatorStepDownCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator usage": func() (cli.Command, error) {
			return &OperatorUsageCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"operator unseal": func() (cli.Command, error) {
			return &OperatorUnsealCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"path-help": func() (cli.Command, error) {
			return &PathHelpCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin": func() (cli.Command, error) {
			return &PluginCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin deregister": func() (cli.Command, error) {
			return &PluginDeregisterCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin info": func() (cli.Command, error) {
			return &PluginInfoCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin list": func() (cli.Command, error) {
			return &PluginListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin register": func() (cli.Command, error) {
			return &PluginRegisterCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin reload": func() (cli.Command, error) {
			return &PluginReloadCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"plugin reload-status": func() (cli.Command, error) {
			return &PluginReloadStatusCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy": func() (cli.Command, error) {
			return &PolicyCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy delete": func() (cli.Command, error) {
			return &PolicyDeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy fmt": func() (cli.Command, error) {
			return &PolicyFmtCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy list": func() (cli.Command, error) {
			return &PolicyListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy read": func() (cli.Command, error) {
			return &PolicyReadCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"policy write": func() (cli.Command, error) {
			return &PolicyWriteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"print": func() (cli.Command, error) {
			return &PrintCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"print token": func() (cli.Command, error) {
			return &PrintTokenCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"read": func() (cli.Command, error) {
			return &ReadCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets": func() (cli.Command, error) {
			return &SecretsCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets disable": func() (cli.Command, error) {
			return &SecretsDisableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets enable": func() (cli.Command, error) {
			return &SecretsEnableCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets list": func() (cli.Command, error) {
			return &SecretsListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets move": func() (cli.Command, error) {
			return &SecretsMoveCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"secrets tune": func() (cli.Command, error) {
			return &SecretsTuneCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"server": func() (cli.Command, error) {
			return &ServerCommand{
				BaseCommand: &BaseCommand{
					UI:          serverCmdUi,
					tokenHelper: runOpts.TokenHelper,
					flagAddress: runOpts.Address,
				},
				AuditBackends:      auditBackends,
				CredentialBackends: credentialBackends,
				LogicalBackends:    logicalBackends,
				PhysicalBackends:   physicalBackends,

				ServiceRegistrations: serviceRegistrations,

				ShutdownCh: MakeShutdownCh(),
				SighupCh:   MakeSighupCh(),
				SigUSR2Ch:  MakeSigUSR2Ch(),
			}, nil
		},
		"ssh": func() (cli.Command, error) {
			return &SSHCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"status": func() (cli.Command, error) {
			return &StatusCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token": func() (cli.Command, error) {
			return &TokenCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token create": func() (cli.Command, error) {
			return &TokenCreateCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token capabilities": func() (cli.Command, error) {
			return &TokenCapabilitiesCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token lookup": func() (cli.Command, error) {
			return &TokenLookupCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token renew": func() (cli.Command, error) {
			return &TokenRenewCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"token revoke": func() (cli.Command, error) {
			return &TokenRevokeCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"unwrap": func() (cli.Command, error) {
			return &UnwrapCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"version": func() (cli.Command, error) {
			return &VersionCommand{
				VersionInfo: version.GetVersion(),
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"write": func() (cli.Command, error) {
			return &WriteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv": func() (cli.Command, error) {
			return &KVCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv put": func() (cli.Command, error) {
			return &KVPutCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv patch": func() (cli.Command, error) {
			return &KVPatchCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv rollback": func() (cli.Command, error) {
			return &KVRollbackCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv get": func() (cli.Command, error) {
			return &KVGetCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv delete": func() (cli.Command, error) {
			return &KVDeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv list": func() (cli.Command, error) {
			return &KVListCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv destroy": func() (cli.Command, error) {
			return &KVDestroyCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv undelete": func() (cli.Command, error) {
			return &KVUndeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv enable-versioning": func() (cli.Command, error) {
			return &KVEnableVersioningCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv metadata": func() (cli.Command, error) {
			return &KVMetadataCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv metadata put": func() (cli.Command, error) {
			return &KVMetadataPutCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv metadata get": func() (cli.Command, error) {
			return &KVMetadataGetCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"kv metadata delete": func() (cli.Command, error) {
			return &KVMetadataDeleteCommand{
				BaseCommand: getBaseCommand(),
			}, nil
		},
		"monitor": func() (cli.Command, error) {
			return &MonitorCommand{
				BaseCommand: getBaseCommand(),
				ShutdownCh:  MakeShutdownCh(),
			}, nil
		},
	}
}

// MakeShutdownCh returns a channel that can be used for shutdown
// notifications for commands. This channel will send a message for every
// SIGINT or SIGTERM received.
func MakeShutdownCh() chan struct{} {
	resultCh := make(chan struct{})

	shutdownCh := make(chan os.Signal, 4)
	signal.Notify(shutdownCh, os.Interrupt, syscall.SIGTERM)
	go func() {
		<-shutdownCh
		close(resultCh)
	}()
	return resultCh
}

// MakeSighupCh returns a channel that can be used for SIGHUP
// reloading. This channel will send a message for every
// SIGHUP received.
func MakeSighupCh() chan struct{} {
	resultCh := make(chan struct{})

	signalCh := make(chan os.Signal, 4)
	signal.Notify(signalCh, syscall.SIGHUP)
	go func() {
		for {
			<-signalCh
			resultCh <- struct{}{}
		}
	}()
	return resultCh
}