open-consul/agent/auto-config/persist.go

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package autoconf
import (
"fmt"
"os"
"path/filepath"
"strings"
"github.com/golang/protobuf/jsonpb"
"github.com/hashicorp/consul/proto/pbautoconf"
)
const (
// autoConfigFileName is the name of the file that the agent auto-config settings are
// stored in within the data directory
autoConfigFileName = "auto-config.json"
)
var (
pbMarshaler = &jsonpb.Marshaler{
OrigName: false,
EnumsAsInts: false,
Indent: " ",
EmitDefaults: true,
}
pbUnmarshaler = &jsonpb.Unmarshaler{
AllowUnknownFields: false,
}
)
func (ac *AutoConfig) readPersistedAutoConfig() (*pbautoconf.AutoConfigResponse, error) {
if ac.config.DataDir == "" {
// no data directory means we don't have anything to potentially load
return nil, nil
}
path := filepath.Join(ac.config.DataDir, autoConfigFileName)
ac.logger.Debug("attempting to restore any persisted configuration", "path", path)
content, err := os.ReadFile(path)
if err == nil {
rdr := strings.NewReader(string(content))
var resp pbautoconf.AutoConfigResponse
if err := pbUnmarshaler.Unmarshal(rdr, &resp); err != nil {
return nil, fmt.Errorf("failed to decode persisted auto-config data: %w", err)
}
ac.logger.Info("read persisted configuration", "path", path)
return &resp, nil
}
if !os.IsNotExist(err) {
return nil, fmt.Errorf("failed to load %s: %w", path, err)
}
// ignore non-existence errors as that is an indicator that we haven't
// performed the auto configuration before
return nil, nil
}
func (ac *AutoConfig) persistAutoConfig(resp *pbautoconf.AutoConfigResponse) error {
// now that we know the configuration is generally fine including TLS certs go ahead and persist it to disk.
if ac.config.DataDir == "" {
ac.logger.Debug("not persisting auto-config settings because there is no data directory")
return nil
}
serialized, err := pbMarshaler.MarshalToString(resp)
if err != nil {
return fmt.Errorf("failed to encode auto-config response as JSON: %w", err)
}
path := filepath.Join(ac.config.DataDir, autoConfigFileName)
err = os.WriteFile(path, []byte(serialized), 0660)
if err != nil {
return fmt.Errorf("failed to write auto-config configurations: %w", err)
}
ac.logger.Debug("auto-config settings were persisted to disk")
return nil
}