Cluster HTTP Management

Pekko Management Cluster HTTP is a Management extension that allows interaction with an pekko-cluster through an HTTP interface. This management extension exposes different operations to manage nodes in a cluster as well as health checks based on the cluster state.

The operations exposed are comparable to the Command Line Management tool or the JMX interface pekko-cluster provides.

Project Info

Project Info: Apache Pekko Management Cluster HTTP
Artifact	org.apache.pekko pekko-management-cluster-http 1.0.0 Snapshots are available
JDK versions	OpenJDK 8 OpenJDK 11
Scala versions	2.12.18, 2.13.12, 3.3.1
License	Apache-2.0
Home page	https://pekko.apache.org/
API documentation	API (Scaladoc)
Forums	Apache Pekko User mailing list Apache Pekko Dev mailing list Github Discussions
Release notes	Release Notes
Issues	GitHub issues
Sources	https://github.com/apache/pekko-management

Dependencies

The Pekko Cluster HTTP Management is a separate jar file. Make sure to include it along with the core pekko-management library in your project:

sbt

val PekkoManagementVersion = "1.0.0"
libraryDependencies ++= Seq(
  "org.apache.pekko" %% "pekko-management" % PekkoManagementVersion,
  "org.apache.pekko" %% "pekko-management-cluster-http" % PekkoManagementVersion
)

Gradle

def versions = [
  PekkoManagementVersion: "1.0.0",
  ScalaBinary: "2.13"
]
dependencies {
  implementation "org.apache.pekko:pekko-management_${versions.ScalaBinary}:${versions.PekkoManagementVersion}"
  implementation "org.apache.pekko:pekko-management-cluster-http_${versions.ScalaBinary}:${versions.PekkoManagementVersion}"
}

Maven

<properties>
  <pekko.management.version>1.0.0</pekko.management.version>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencies>
  <dependency>
    <groupId>org.apache.pekko</groupId>
    <artifactId>pekko-management_${scala.binary.version}</artifactId>
    <version>${pekko.management.version}</version>
  </dependency>
  <dependency>
    <groupId>org.apache.pekko</groupId>
    <artifactId>pekko-management-cluster-http_${scala.binary.version}</artifactId>
    <version>${pekko.management.version}</version>
  </dependency>
</dependencies>

Pekko Cluster HTTP Management can be used with Apache Pekko 1.0.2 or later. You have to override the following Pekko dependencies by defining them explicitly in your build and define the Pekko version to the one that you are using. Latest patch version of Pekko is recommended and a later version than 1.0.2 can be used.

sbt

val PekkoVersion = "1.0.2"
libraryDependencies ++= Seq(
  "org.apache.pekko" %% "pekko-cluster-sharding" % PekkoVersion,
  "org.apache.pekko" %% "pekko-discovery" % PekkoVersion
)

Gradle

def versions = [
  PekkoVersion: "1.0.2",
  ScalaBinary: "2.13"
]
dependencies {
  implementation "org.apache.pekko:pekko-cluster-sharding_${versions.ScalaBinary}:${versions.PekkoVersion}"
  implementation "org.apache.pekko:pekko-discovery_${versions.ScalaBinary}:${versions.PekkoVersion}"
}

Maven

<properties>
  <pekko.version>1.0.2</pekko.version>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencies>
  <dependency>
    <groupId>org.apache.pekko</groupId>
    <artifactId>pekko-cluster-sharding_${scala.binary.version}</artifactId>
    <version>${pekko.version}</version>
  </dependency>
  <dependency>
    <groupId>org.apache.pekko</groupId>
    <artifactId>pekko-discovery_${scala.binary.version}</artifactId>
    <version>${pekko.version}</version>
  </dependency>
</dependencies>

Running

To make sure the Pekko Cluster HTTP Management is running, register it with Pekko Management:

Scala

sourceval system = ActorSystem()
// Automatically loads Cluster Http Routes
PekkoManagement(system).start()

Java

sourceActorSystem system = ActorSystem.create();
PekkoManagement.get(system).start();

API Definition

The following table describes the usage of the API. All GET operations are exposed by default. POST, PUT and DELETE operations are only enabled if pekko.management.http.route-providers-read-only is set to false.

Path	HTTP method	Required form fields	Description
`/cluster/`	PUT	operation: Prepare-for-full-shutdown	Executes a prepare for full shutdown operation in cluster.
`/cluster/domain-events`	GET	None	Returns cluster domain events as they occur, in JSON-encoded SSE format.
`/cluster/members/`	GET	None	Returns the status of the Cluster in JSON format.
`/cluster/members/`	POST	address: `{address}`	Executes join operation in cluster for the provided `{address}`.
`/cluster/members/{address}`	GET	None	Returns the status of `{address}` in the Cluster in JSON format.
`/cluster/members/{address}`	DELETE	None	Executes leave operation in cluster for provided `{address}`.
`/cluster/members/{address}`	PUT	operation: Down	Executes down operation in cluster for provided `{address}`.
`/cluster/members/{address}`	PUT	operation: Leave	Executes leave operation in cluster for provided `{address}`.
`/cluster/shards/{name}`	GET	None	Returns shard info for the shard region with the provided `{name}`

The expected format of address follows the Cluster URI convention. Example: pekko://Main@myhostname.com:3311

In the paths address is also allowed to be provided without the protocol prefix. Example: Main@myhostname.com:3311

Get /cluster/domain-events request query parameters

Query Parameter	Description
type	Optional. Specify event type(s) to include in response (see table). If not specified, all event types are included.

Event Type	Description
ClusterDomainEvent	cluster domain event (parent)
MemberEvent	membership event (parent)
MemberJoined	membership event - joined
MemberWeaklyUp	membership event - transitioned to WeaklyUp
MemberUp	membership event - transitioned to Up
MemberLeft	membership event - left
MemberExited	membership event - exited
MemberDowned	membership event - downed
MemberRemoved	membership event - removed
LeaderChanged	cluster’s leader has changed
RoleLeaderChanged	cluster’s role leader has changed
ClusterShuttingDown	cluster is shutting down
ReachabilityEvent	reachability event (parent)
UnreachableMember	reachability event - member now unreachable
ReachableMember	reachability event - member now reachable
DataCenterReachabilityEvent	DC reachability event (parent)
UnreachableDataCenter	DC reachability event - DC now unreachable
ReachableDataCenter	DC reachability event - DC now reachable

Example request:

GET /cluster/domain-events?type=MemberUp&type=LeaderChanged HTTP/1.1
Host: 192.168.1.23:7626

Example response:

HTTP/1.1 200 OK
Server: pekko-http/1.0.0
Date: Mon, 11 Jan 2021 21:02:37 GMT
Transfer-Encoding: chunked
Content-Type: text/event-stream

data:{"member":{"dataCenter":"default","roles":["dc-default"],"status":"Up","uniqueAddress":{"address":"pekko://default@127.0.0.1:2551","longUid":-2440990093160003086}},"type":"MemberUp"}
event:MemberUp

data:{"address":"pekko://default@127.0.0.1:2551","type":"LeaderChanged"}
event:LeaderChanged

Get /cluster/domain-events responses

Response code	Description
200	Cluster events in Server-Sent-Event format (JSON)
500	Something went wrong.

Get /cluster/members responses

Response code	Description
200	Status of cluster in JSON format
500	Something went wrong. Cluster might be shutdown.

Example response:

 {
   "selfNode": "pekko.tcp://test@10.10.10.10:1111",
   "members": [
     {
       "node": "pekko.tcp://test@10.10.10.10:1111",
       "nodeUid": "1116964444",
       "status": "Up",
       "roles": []
     }
   ],
   "unreachable": [],
   "leader: "pekko.tcp://test@10.10.10.10:1111",
   "oldest: "pekko.tcp://test@10.10.10.10:1111"
 }

Where oldest is the oldest node in the current datacenter.

Post /cluster/members responses

Response code	Description
200	Executing join operation.
500	Something went wrong. Cluster might be shutdown.

Example response:

Joining pekko.tcp://test@10.10.10.10:111

Get /cluster/members/{address} responses

Response code	Description
200	Status of cluster in JSON format
404	No member was found in the cluster for the given `{address}`.
500	Something went wrong. Cluster might be shutdown.

Example response:

{
  "node": "pekko.tcp://test@10.10.10.10:1111",
  "nodeUid": "-169203556",
  "status": "Up",
  "roles": []
}

Delete /cluster/members/{address} responses

Response code	Description
200	Executing leave operation.
404	No member was found in the cluster for the given `{address}`.
500	Something went wrong. Cluster might be shutdown.

Example response:

Leaving pekko.tcp://test@10.10.10.10:111

Put /cluster/members/{address} responses

Response code	Operation	Description
200	Down	Executing down operation.
200	Leave	Executing leave operation.
400		Operation supplied in `operation` form field is not supported.
404		No member was found in the cluster for the given `{address}`
500		Something went wrong. Cluster might be shutdown.

Example response:

Downing pekko.tcp://test@10.10.10.10:111

Get /cluster/shard responses

Response code	Description
200	Shard entity type keys in JSON format

Example response:

{ “entityTypeKeys”: [“ShoppingCart”] }

Get /cluster/shards/{name} responses

Response code	Description
200	Shard region information in JSON format
404	No shard region was found on the node for the given `{name}`

Example response:

 {
   "regions": [
     {
       "shardId": "1234",
       "numEntities": 30
     }
   ]
 }

Hosting the routes in an existing Pekko HTTP server

Starting PekkoMangement starts a Pekko HTTP server and hosts the Cluster HTTP Routes. The routes can also be added to an existing Pekko HTTP server. To access all the routes:

Scala

sourceval cluster = Cluster(system)
val allRoutes: Route = ClusterHttpManagementRoutes(cluster)

Java

sourceCluster cluster = Cluster.get(system);
Route allRoutes = ClusterHttpManagementRoutes.all(cluster);

Just the read only routes can be accessed:

Scala

sourceval readOnlyRoutes: Route = ClusterHttpManagementRoutes.readOnly(cluster)

Java

sourceRoute readOnlyRoutes = ClusterHttpManagementRoutes.readOnly(cluster);

Disable routes

The Cluster HTTP Routes are included by default when this module is used. It can be disabled with the following configuration, for example if the cluster membership health checks are to be included but not the other Cluster HTTP Routes.

pekko.management.http.routes {
  cluster-management = ""
}

Health checks

A cluster membership health check is included that is designed to be used as a readiness check.

By default the health check returns true when a node is either Up or WeaklyUp. Can be configured with pekko.management.cluster.health-checks.ready-states.

The cluster membership readiness check can be disabled with configuration:

pekko.management.health-checks.readiness-checks {
  cluster-membership = ""
}

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