snapshot

Documentation

Overview

The archive utilities manage the internal format of a snapshot, which is a tar file with the following contents:

meta.json - JSON-encoded snapshot metadata from Raft state.bin - Encoded snapshot data from Raft SHA256SUMS - SHA-256 sums of the above two files

The integrity information is automatically created and checked, and a failure there just looks like an error to the caller.

snapshot manages the interactions between Nomad and Raft in order to take and restore snapshots for disaster recovery. The internal format of a snapshot is simply a tar file, as described in archive.go.

Index

• func CopySnapshot(in io.Reader, dest io.Writer) (*raft.SnapshotMeta, error)
• func Restore(logger hclog.Logger, in io.Reader, r *raft.Raft) error
• func Verify(in io.Reader) (*raft.SnapshotMeta, error)
• type Snapshot
  • func New(logger hclog.Logger, r *raft.Raft) (*Snapshot, error)
  • func (s *Snapshot) Checksum() string
  • func (s *Snapshot) Close() error
  • func (s *Snapshot) Index() uint64
  • func (s *Snapshot) Read(p []byte) (n int, err error)

Functions

func CopySnapshot

func CopySnapshot(in io.Reader, dest io.Writer) (*raft.SnapshotMeta, error)

CopySnapshot copies the snapshot content from snapshot archive to dest

func Restore

func Restore(logger hclog.Logger, in io.Reader, r *raft.Raft) error

Restore takes the snapshot from the reader and attempts to apply it to the given Raft instance.

func Verify

func Verify(in io.Reader) (*raft.SnapshotMeta, error)

Verify takes the snapshot from the reader and verifies its contents.

Types

type Snapshot

type Snapshot struct {
	// contains filtered or unexported fields
}

Snapshot is a structure that holds state about a temporary file that is used to hold a snapshot. By using an intermediate file we avoid holding everything in memory.

func New

func New(logger hclog.Logger, r *raft.Raft) (*Snapshot, error)

New takes a state snapshot of the given Raft instance into a temporary file and returns an object that gives access to the file as an io.Reader. You must arrange to call Close() on the returned object or else you will leak a temporary file.

func (*Snapshot) Checksum

func (s *Snapshot) Checksum() string

func (*Snapshot) Close

func (s *Snapshot) Close() error

Close closes the snapshot and removes any temporary storage associated with it. You must arrange to call this whenever NewSnapshot() has been called successfully. This is safe to call on a nil snapshot.

func (*Snapshot) Index

func (s *Snapshot) Index() uint64

Index returns the index of the snapshot. This is safe to call on a nil snapshot, it will just return 0.

func (*Snapshot) Read

func (s *Snapshot) Read(p []byte) (n int, err error)

Read passes through to the underlying snapshot file. This is safe to call on a nil snapshot, it will just return an EOF.