# MinIO Grid

The MinIO Grid is a package that provides two-way communication between servers.
It uses a single two-way connection to send and receive messages between servers.

It includes built in muxing of concurrent requests as well as congestion handling for streams.

Requests can be "Single Payload" or "Streamed".

Use the MinIO Grid for:

* Small, frequent requests with low latency requirements.

**NOTE**: When configuring multiple OpenID based authentication providers on a MinIO cluster, any number of Role Policy based providers may be configured, and at most one JWT Claim based provider may be configured.

<details><summary>Example 1: Two role policy providers</summary>

Sample environment variables:

```

		mpath := strings.TrimSuffix(mount.Path, "/") + "/"
		ppath := strings.TrimSuffix(path, "/") + "/"
		if strings.HasPrefix(mpath, ppath) {
			// At this point if the mount point has a common prefix two conditions can happen.
			// - mount.Path matches exact with `path` means we can proceed no error here.
			// - mount.Path doesn't match (means cross-device mount), should error out.
			if mount.Path != path {

			t := kafka.New(l)
			tgts = append(tgts, t)

			e := t.Init(ctx)
			if e != nil {
				errs = append(errs, e)
			}
		}
	}
	return tgts, errs
}

// Split targets into two groups:
//
//	group1 contains all targets of type t
//	group2 contains the remaining targets
func splitTargets(targets []Target, t types.TargetType) (group1 []Target, group2 []Target) {
	for _, target := range targets {

type ServerSystemConfig struct {
	NEndpoints int
	CmdLines   []string
	MinioEnv   map[string]string
}

// Diff - returns error on first difference found in two configs.
func (s1 *ServerSystemConfig) Diff(s2 *ServerSystemConfig) error {
	ns1 := s1.NEndpoints
	ns2 := s2.NEndpoints
	if ns1 != ns2 {
		return fmt.Errorf("Expected number of endpoints %d, seen %d", ns1, ns2)
	}

// These messages appear in responses at random. The client must detect the message type and process accordingly.
//
// Header specification:
// Continuation messages contain two headers, as follows:
// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-cont.png
//
// Payload specification:
// Continuation messages have no payload.
var continuationMessage = []byte{

. . .
```

Refer [Prometheus documentation](https://prometheus.io/docs/introduction/first_steps/) for more details.

### 2. Configure authentication type for Prometheus metrics

MinIO supports two authentication modes for Prometheus either `jwt` or `public`, by default MinIO runs in `jwt` mode. To allow public access without authentication for prometheus metrics set environment as follows.

```

		return cred, owner, ErrAccessKeyDisabled
	}

	if _, ok := claims[policy.SessionPolicyName]; ok {
		owner = false
	}

	return cred, owner, ErrNone
}

// sumHMAC calculate hmac between two input byte array.
func sumHMAC(key []byte, data []byte) []byte {
	hash := hmac.New(sha256.New, key)
	hash.Write(data)
	return hash.Sum(nil)
}

	}
	return releaseTime, err
}

// parseReleaseData - parses release info file content fetched from
// official minio download server.
//
// The expected format is a single line with two words like:
//
// fbe246edbd382902db9a4035df7dce8cb441357d minio.RELEASE.2016-10-07T01-16-39Z.<hotfix_optional>
//
// The second word must be `minio.` appended to a standard release tag.

// Both type and value must match.
func (v Value) Equals(b Value) (ok bool) {
	if !v.SameTypeAs(b) {
		return false
	}
	return reflect.DeepEqual(v.value, b.value)
}

// SameTypeAs return whether the two types are strictly the same.
func (v Value) SameTypeAs(b Value) (ok bool) {
	switch v.value.(type) {
	case bool:
		_, ok = b.value.(bool)
	case string:
		_, ok = b.value.(string)
	case int64: