mirror of
https://github.com/psviderski/uncloud.git
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121 lines
3.4 KiB
Go
121 lines
3.4 KiB
Go
package machine
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import (
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"encoding/json"
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"fmt"
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"os"
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"path/filepath"
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"sync"
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"github.com/psviderski/uncloud/internal/machine/network"
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)
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const (
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DefaultDataDir = "/var/lib/uncloud"
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StateFileName = "machine.json"
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)
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// State defines the machine-specific configuration within a cluster. It encapsulates essential identifiers
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// and settings required to establish an overlay network and operate as a member of a cluster.
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type State struct {
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// ID uniquely identifies this machine in the cluster.
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ID string
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// Name provides a human-readable identifier for the machine.
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Name string
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// Network specifies the network configuration for this machine.
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Network *network.Config
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// MinStoreVersion is the cluster store version this machine must reach before participating.
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// Per-actor vector (Corrosion actor UUID → max applied db_version) captured from an existing
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// member at join time. Cleared once reached.
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MinStoreVersion map[string]int64 `json:",omitempty"`
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// path is the file path config is read from and saved to.
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path string
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// mu protects the state from concurrent reads and writes.
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mu sync.RWMutex
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}
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// StatePath returns the path to the machine state file within the given data directory.
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func StatePath(dataDir string) string {
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return filepath.Join(dataDir, StateFileName)
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}
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// ParseState reads and decodes a state from the file at the given path.
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func ParseState(path string) (*State, error) {
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data, err := os.ReadFile(path)
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if err != nil {
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return nil, fmt.Errorf("read state file: %w", err)
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}
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state := State{path: path}
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if err = json.Unmarshal(data, &state); err != nil {
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return nil, fmt.Errorf("parse state file %q: %w", path, err)
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}
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if state.Network == nil {
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return nil, fmt.Errorf("missing network configuration in state file %q", path)
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}
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return &state, nil
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}
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// SetPath sets the file path the state can be saved to.
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func (c *State) SetPath(path string) {
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c.path = path
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}
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// Encode returns the JSON encoded state data.
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func (c *State) Encode() ([]byte, error) {
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data, err := json.MarshalIndent(c, "", " ")
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if err != nil {
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return nil, fmt.Errorf("marshal config: %w", err)
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}
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return data, nil
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}
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// Save atomically writes the state data to the file at the configured path.
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func (c *State) Save() error {
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if c.path == "" {
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return fmt.Errorf("state path not set")
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}
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dir, _ := filepath.Split(c.path)
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if err := os.MkdirAll(dir, 0o711); err != nil {
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return fmt.Errorf("create state directory %q: %w", dir, err)
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}
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data, err := c.Encode()
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if err != nil {
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return err
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}
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// Write to a temporary file and rename for atomic save. CreateTemp creates a file with mode 0o600.
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tmpFile, err := os.CreateTemp(dir, ".machine.json.*")
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if err != nil {
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return fmt.Errorf("create temp file: %w", err)
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}
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tmpPath := tmpFile.Name()
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// Clean up temp file on error.
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defer func() {
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if err != nil {
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os.Remove(tmpPath)
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}
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}()
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if _, err = tmpFile.Write(data); err != nil {
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tmpFile.Close()
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return fmt.Errorf("write temp file: %w", err)
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}
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// Without fsync, the data may only be in the OS buffer cache. If the system crashes before the OS flushes
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// it to disk, the file could be empty or corrupted even after rename.
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if err = tmpFile.Sync(); err != nil {
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tmpFile.Close()
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return fmt.Errorf("sync temp file: %w", err)
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}
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if err = tmpFile.Close(); err != nil {
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return fmt.Errorf("close temp file: %w", err)
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}
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if err = os.Rename(tmpPath, c.path); err != nil {
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return fmt.Errorf("rename temp file: %w", err)
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}
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return nil
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}
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