dotcloud/docker

package cluster // import "github.com/docker/docker/daemon/cluster"

import (
    "encoding/json"
    "os"
    "path/filepath"
    "strings"

    "github.com/docker/docker/pkg/ioutils"
)

// convertKVStringsToMap converts ["key=value"] to {"key":"value"}
func convertKVStringsToMap(values []string) map[string]string {
    result := make(map[string]string, len(values))
    for _, value := range values {
        k, v, _ := strings.Cut(value, "=")
        result[k] = v
    }

    return result
}

func loadPersistentState(root string) (*nodeStartConfig, error) {
    dt, err := os.ReadFile(filepath.Join(root, stateFile))
    if err != nil {
        return nil, err
    }
    // missing certificate means no actual state to restore from
    if _, err := os.Stat(filepath.Join(root, "certificates/swarm-node.crt")); err != nil {
        if os.IsNotExist(err) {
            clearPersistentState(root)
        }
        return nil, err
    }
    var st nodeStartConfig
    if err := json.Unmarshal(dt, &st); err != nil {
        return nil, err
    }
    return &st, nil
}

func savePersistentState(root string, config nodeStartConfig) error {
    dt, err := json.Marshal(config)
    if err != nil {
        return err
    }
    return ioutils.AtomicWriteFile(filepath.Join(root, stateFile), dt, 0o600)
}

func clearPersistentState(root string) error {
    // todo: backup this data instead of removing?
    // rather than delete the entire swarm directory, delete the contents in order to preserve the inode
    // (for example, allowing it to be bind-mounted)
    files, err := os.ReadDir(root)
    if err != nil {
        return err
    }

    for _, f := range files {
        if err := os.RemoveAll(filepath.Join(root, f.Name())); err != nil {
            return err
        }
    }

    return nil
}

func removingManagerCausesLossOfQuorum(reachable, unreachable int) bool {
    return reachable-2 <= unreachable
}

func isLastManager(reachable, unreachable int) bool {
    return reachable == 1 && unreachable == 0
}