)

// Legacy OPA envs
const (
	EnvIamOpaURL       = "MINIO_IAM_OPA_URL"
	EnvIamOpaAuthToken = "MINIO_IAM_OPA_AUTHTOKEN"
)

// SetPolicyOPAConfig - One time migration code needed, for migrating from older config to new for PolicyOPAConfig.
func SetPolicyOPAConfig(s config.Config, opaArgs Args) {
	if opaArgs.URL == nil || opaArgs.URL.String() == "" {
		// Do not enable if opaArgs was empty.
		return
	}

// parseJSON parses both the old and the new format for storing policy
// definitions.
//
// The on-disk format of policy definitions has changed (around early 12/2021)
// from policy.Policy to PolicyDoc. To avoid a migration, loading supports
// both the old and the new formats.
func (d *PolicyDoc) parseJSON(data []byte) error {
	json := jsoniter.ConfigCompatibleWithStandardLibrary
	var doc PolicyDoc
	err := json.Unmarshal(data, &doc)

No, an upgrade should not cause any downtime. However, on the first startup -
since MinIO will attempt to migrate any existing IAM data - the boot process may
take slightly longer, but may not be visibly noticeable. Once the migration has

		// Preserve older credential if we do not have
		// root credentials set via environment variable.
		globalActiveCred = cfg.Credential
	}

	// Init compression config. For future migration, Compression config needs to be copied over from previous version.
	switch cfg.Version {
	case "29":
		// V29 -> V30
		cfg.Compression.Enabled = false

	}
	if err == nil {
		b.defaultTimestamps()
	}

	// If bucket metadata is missing look for legacy files,
	// since we only ever had b.Created as non-zero when
	// migration was complete in 2020-May release. So this
	// a check to avoid migrating for buckets that already
	// have this field set.
	if b.Created.IsZero() {
		configs, err := b.getAllLegacyConfigs(ctx, objectAPI)
		if err != nil {
			return b, err
		}

)

// Legacy envs
const (
	legacyEnvAuditLoggerHTTPEndpoint = "MINIO_AUDIT_LOGGER_HTTP_ENDPOINT"
	legacyEnvLoggerHTTPEndpoint      = "MINIO_LOGGER_HTTP_ENDPOINT"
)

// SetLoggerHTTPAudit - helper for migrating older config to newer KV format.
func SetLoggerHTTPAudit(scfg config.Config, k string, args http.Config) {
	if !args.Enabled {
		// Do not enable audit targets, if not enabled
		return
	}

	go renameAllBucketMetacache(diskPath)
}

// Following error message is added to fix a regression in release
// RELEASE.2018-03-16T22-52-12Z after migrating v1 to v2 to v3. This
// migration failed to capture '.This' field properly which indicates
// the disk UUID association. Below error message is returned when
// we see this situation in format.json, for more info refer

	// the following reasons:
	//  - Read quorum is lost just after the initialization
	//    of the object layer.
	//  - Write quorum not met when upgrading configuration
	//    version is needed, migration is needed etc.
	rquorum := InsufficientReadQuorum{}
	wquorum := InsufficientWriteQuorum{}

	// One of these retriable errors shall be retried.
	return errors.Is(err, errDiskNotFound) ||

### Step 1: Ensure Elasticsearch minimum requirements are met

MinIO requires a 5.x series version of Elasticsearch. This is the latest major release series. Elasticsearch provides version upgrade migration guidelines [here](https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-upgrade.html).

### Step 2: Add Elasticsearch endpoint to MinIO