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Cloud Native Federation Middleware -- FedState Officially Open Sourced

In the cloud native scenario, there has been great development of stateful services. Some games are based on YAML packaging for manual installation, some are based on helm charts, and some are wrapped based on operator methods. At present, the community's methods are mainly based on helm chart and operator, especially based on operator, because it is a programming-friendly method and can develop various capabilities according to needs. Currently, there are also many open source middleware and database operators in the community, but they are mainly concentrated in the single-cluster game, which is related to the Operator framework itself. In a multi-cloud/federation environment, how to design and implement the scheduling, deployment, and automated operation and maintenance of stateful services based on multiple clusters, multiple data centers, and hybrid cloud scenarios? The newly open-sourced FedState project is trying to solve such situation problems.

The open-source repository address of FedState is: https://github.com/fedstate/fedstate. Next, we will introduce FedState in conjunction with MongoDB as an example.

Demand Analysis

First of all, let's roughly analyze what requirements customers have for middleware usage in multi-cloud scenarios.

  • Deploy middleware across container clusters/data centers.
  • Unified control plane and multi-layer architecture specifications for data plane.
  • Resource statistics capability of member container cluster.
  • Reasonable scheduling of middleware load according to member container cluster resources.
  • Flexibly adapt to different middleware characteristics to complete scheduling.
  • Discovery between middleware components across container clusters.
  • Unified external access entry of clusters.
  • Topology of middleware clusters across multiple clusters.
  • Expansion of middleware clusters.
  • Contraction of middleware clusters.
  • Data replication/disaster recovery capabilities across container clusters.
  • Automated operation and maintenance ability of middleware clusters.
  • Cloud native service delivery.
  • The ability to manage middleware clusters in a page.
  • Open API capability for easy construction of upper layer capabilities.
  • Openness of storage, compatible with CSI.
  • Tenant isolation.
  • Support for multiple versions of middleware.
  • Monitoring, alarm and other abilities.

Architecture Introduction

Currently, FedState has implemented the framework of federation middleware, and also built-in the middleware capabilities of federation MongoDB and single-cluster MongoDB. The control plane and data plane are relatively independent. Single-cluster MongoDB Manager can be used directly in the single-cluster scenario, or MongoDB capabilities in the federation scenario can be used. At the same time, the federation MongoDB uses the single-cluster mode MongoDB Manager.

Here, taking the federation MongoDB as an example, the following architecture diagram introduces the overall capabilities provided by FedState around the MongoDB replica set in multi-cloud/multi-cluster environment.

image

FedState itself contains the following components:

Multicloud-Middleware-Scheduler: is responsible for collecting the resource usage of the working cluster and giving reasonable scheduling methods based on the resource usage. At the same time, different middleware have their own characteristics, and there will be corresponding special scheduling logic for different middleware to help various middleware choose suitable scheduling results. Different types of middleware scheduling strategies and implementations can be extended according to needs.

Federation-Mongo-Manager: can be understood as the operator of MongoDB control plane, which is mainly responsible for on-demand configuration of these middleware services, reasonable scheduling, and distribution through Karmada. Different middleware can be expanded as needed.

Mongo-Manager: can be understood as the operator of MongoDB data plane, which is mainly responsible for the processing of real service loads. Different middleware can be expanded as needed. Here, you can also choose excellent open-source operators, as long as the operator itself meets the requirements of the control plane for data plane operators, as long as expansion is performed in the control plane, this middleware can be supported to make it have the ability of federation middleware.

Key capabilities

image

  1. The external access method of the federation MongoDB instance: Vip0:NodePort0, Vip1:NodePort1...
  2. East-west traffic and service discovery between MongoDB services in each member cluster are used to correspond to the NodePort method corresponding to the VIP+service of the cluster.
  3. In addition to supporting the creation and updating of federation MongoDB replica sets, etc., you can also directly use the data plane operator to create and manage MongoDB clusters in single-cluster mode.
  4. According to the characteristics of different middleware, nodes with different roles are deployed in different clusters to ensure the high availability requirements of middleware.
  5. Support manual adjustment of cluster scale to complete expansion and contraction capabilities.
  6. Support fault migration based on Karmada and custom migration strategies.
  7. Support monitoring in Prometheus mode to collect metrics data of MongoDB nodes.
  8. Custom configuration files can be set according to needs to set various configuration items supported by MongoDB.
  9. Support MongoDB cluster authentication to authenticate client connections.
  10. Support CSI storage to persist middleware data.
  11. Support the topology of MongoDB clusters, and clearly observe the running status of each MongoDB node.
  12. Support MongoDB replica set mode to build MongoDB clusters.

Business Model

Taking MongoDB as an example, some common capabilities provided in the federation and single-cluster modes are introduced:

MongoDB cluster in federation mode

Creating and managing resource objects of stateful services in federation will distribute stateful services to member clusters according to configuration, set the required storage, turn on monitoring, password configuration, etc. After successful creation, the deployment topology and access address of MongoDB in each member cluster will be displayed in the status. This mode is suitable for installing and managing MongoDB clusters across different clusters using control plane and data plane MongoDB Operators in a federation environment.

Click to check MultiCloudMongoDB YAML sample 
apiVersion: middleware.fedstate.io/v1alpha1
kind: MultiCloudMongoDB
metadata:
  name: multicloudmongodb-sample
spec:
  replicaset: 5 # replicas
  export: # config monitor
    enable: true
    resource:
      limits:
        cpu: "500m"
        memory: 512Mi
      requests:
        cpu: "200m"
        memory: 256Mi
  resource: # stateful service resource config
    limits:
      cpu: "2"
      memory: 512Mi
    requests:
      cpu: "1"
      memory: 512Mi
  storage: # storage config
    storageClass: managed-nfs-storage
    storageSize: 1Gi
  imageSetting: # image settings
    image: mongo:3.6
    imagePullPolicy: Always
    imagePullSecret: "my-image-secret"
  auth: # password settings
    rootPasswd: "mypasswd"
  config: # stateful service config
    arbiter: false
    configRef: "my-custome-configmap"
  scheduler: # scheduling and models
    schedulerMode: Uniform
  spreadConstraints: # scheduling and node selection
    nodeSelect:
      deploy: mongo

MongoDB Cluster in Single-Cluster Mode

Creating and managing resource objects for stateful services, this mode is suitable for directly installing and managing MongoDB clusters using the data plane MongoDB Operator in a single-cluster scenario.

Click to check MongoDB YAML sample 
apiVersion: middleware.fedstate.io/v1alpha1
kind: MongoDB
metadata:
  name: mongodb-sample
spec:
  members: 1 # number of replicas
  image: mongo:3.6 # specify a version of MongoDB to deploy, default is MongoDB 6.0
  imagePullSecret: # image pull authentication information
    username: admin
    password: admin
  imagePullPolicy: Always # image pull policy
  config: # fill in according to the configuration of MongoDB
     - name: LOG_LEVEL
       value: info
  customConfigRef: mongo-operator-mongo-default-config # custom MongoDB config, specify cm name, default is mongo-default-config
  rootPassword: "123456" # specify initial password
  resources:
    limits:
      cpu: "1"
      memory: 512Mi
    requests:
      cpu: "1"
      memory: 512Mi
  persistence: # persistence parameters
    storage: 1Gi
    storageClassName: "" # storage type, default is empty, use default sc
  metricsExporterSpec:
    enable: true # whether monitoring is enabled, default is true
    resources:
      limits:
        cpu: "0.1"
        memory: 128Mi
      requests:
        cpu: "0.1"
        memory: 128Mi
  podSpec:
    nodeSelector: # node selector
    securityContext: # pod security context
    topologySpreadConstraints: # topology spread constraints
    affinity: # affinity and anti-affinity
    tolerations: # taint tolerations

Case Introduction

Although there are two modes, federation and single-cluster, this case demonstrates an example using the federation mode.

Deploying a Federation MongoDB Cluster CR on the Control Plane

apiVersion: middleware.fedstate.io/v1alpha1
kind: MultiCloudMongoDB
metadata:
  name: multicloudmongodb-sample
spec:
  replicaset: 5
  export:
    enable: false
  resource:
    limits:
      cpu: "2"
      memory: 512Mi
    requests:
      cpu: "1"
      memory: 512Mi
  storage:
    storageClass: managed-nfs-storage
    storageSize: 1Gi
  imageSetting:
    image: mongo:3.6
    imagePullPolicy: Always

Viewing the Status of MongoDB CR Instance on the Control Plane

Click to check MultiCloudMongoDB YAML sample 
apiVersion: middleware.fedstate.io/v1alpha1
kind: MultiCloudMongoDB
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"middleware.fedstate.io/v1alpha1","kind":"MultiCloudMongoDB","metadata":{"annotations":{},"name":"multicloudmongodb-sample","namespace":"federation-mongo-operator"},"spec":{"export":{"enable":false},"imageSetting":{"image":"mongo:3.6","imagePullPolicy":"Always"},"replicaset":5,"resource":{"limits":{"cpu":"2","memory":"512Mi"},"requests":{"cpu":"1","memory":"512Mi"}},"storage":{"storageClass":"managed-nfs-storage","storageSize":"1Gi"}}}
    schedulerResult: '{"ClusterWithReplicaset":[{"cluster":"10-29-14-21","replicaset":4},{"cluster":"10-29-14-25","replicaset":1}]}'
  creationTimestamp: "2023-05-25T07:06:26Z"
  finalizers:
  - multiCloudMongoDB.finalizers.middleware.fedstate.io
  generation: 1
  name: multicloudmongodb-sample
  namespace: federation-mongo-operator
  resourceVersion: "72770747"
  uid: 56c69f88-6c52-4886-a922-9ebf7c156ba5
spec:
  auth:
    rootPasswd: 39nZzksAmXE=
  config: {}
  export:
    resource: {}
  imageSetting:
    image: mongo:3.6
    imagePullPolicy: Always
    imagePullSecret: {}
  member: {}
  replicaset: 5
  resource:
    limits:
      cpu: "2"
      memory: 512Mi
    requests:
      cpu: "1"
      memory: 512Mi
  scheduler:
    schedulerMode: Uniform
    schedulerName: multicloud-middleware-scheduler
  spreadConstraints: {}
  storage:
    storageClass: managed-nfs-storage
    storageSize: 1Gi
status:
  conditions:
  - lastTransitionTime: "2023-05-25T07:07:57Z"
    message: Service Dispatch Successful And Ready For External Service
    reason: ServerReady
    status: "True"
    type: ServerReady
  - lastTransitionTime: "2023-05-25T07:06:26Z"
    message: 'The number of member clusters is the same as the number of control plane
      copies, check, SpecReplicaset: 5'
    reason: CheckSuccess
    status: "True"
    type: ServerCheck
  - lastTransitionTime: "2023-05-25T07:06:26Z"
    message: 'Get Scheduler Result From MultiCloudMongoDB Annotations Success (federation-mongo-operator/multicloudmongodb-sample):
      {"ClusterWithReplicaset":[{"cluster":"10-29-14-21","replicaset":4},{"cluster":"10-29-14-25","replicaset":1}]}'
    reason: GetSchedulerSuccess
    status: "True"
    type: ServerScheduledResult
  externalAddr: 10.29.5.103:33498,10.29.5.103:38640,10.29.5.103:37661,10.29.5.103:35880,10.29.5.107:38640
  result:
  - applied: true
    cluster: 10-29-14-21
    connectAddrWithRole:
      10.29.5.103:33498: SECONDARY
      10.29.5.103:35880: SECONDARY
      10.29.5.103:37661: SECONDARY
      10.29.5.103:38640: PRIMARY
    currentRevision: multicloudmongodb-sample-666cb9cb8
    replicasetSpec: 4
    replicasetStatus: 4
    state: Running
  - applied: true
    cluster: 10-29-14-25
    connectAddrWithRole:
     10.29.5.107:38640: SECONDARY
    currentRevision: multicloudmongodb-sample-866554df84
    replicasetSpec: 1
    replicasetStatus: 1
    state: Running
  state: Health

Viewing the MongoDB CR Instance Derived from the Data Plane

Click to check MongoDB YAML sample 
apiVersion: middleware.fedstate.io/v1alpha1
kind: MongoDB
metadata:
  annotations:
    resourcebinding.karmada.io/name: multicloudmongodb-sample-mongodb
    resourcebinding.karmada.io/namespace: federation-mongo-operator
    resourcetemplate.karmada.io/uid: 66c5d156-88f7-445f-b068-15dcb327e452
  creationTimestamp: "2023-05-25T07:06:26Z"
  finalizers:
  - mongodb.finalizers.middleware.fedstate.io
  generation: 1
  labels:
    app.kubernetes.io/instance: multicloudmongodb-sample
    app.multicloudmongodb.io/vip: 10.29.5.103
    propagationpolicy.karmada.io/name: multicloudmongodb-sample
    propagationpolicy.karmada.io/namespace: federation-mongo-operator
    resourcebinding.karmada.io/key: 8484fbdb6f
    work.karmada.io/name: multicloudmongodb-sample-8484fbdb6f
    work.karmada.io/namespace: karmada-es-10-29-14-21
  name: multicloudmongodb-sample
  namespace: federation-mongo-operator
  resourceVersion: "232973338"
  selfLink: /apis/middleware.fedstate.io/v1alpha1/namespaces/federation-mongo-operator/mongodbs/multicloudmongodb-sample
  uid: f53b0751-ba6e-4172-b52a-e4ba611b522f
spec:
  dbUserSpec: {}
  image: mongo:3.6
  imagePullPolicy: IfNotPresent
  imagePullSecret: {}
  memberConfigRef: multicloudmongodb-sample-hostconf
  members: 4
  metricsExporterSpec:
    enable: false
  persistence:
    storage: 1Gi
  resources:
    limits:
      cpu: "2"
      memory: 512Mi
    requests:
      cpu: "1"
      memory: 512Mi
  rootPassword: 39nZzksAmXE=
  rsInit: true
  type: ReplicaSet
status:
  conditions:
  - lastTransitionTime: "2023-05-25T07:07:25Z"
    message: replset-0
    status: "True"
    type: rsInit
  - lastTransitionTime: "2023-05-25T07:07:38Z"
    message: replset-0
    status: "True"
    type: userRoot
  - lastTransitionTime: "2023-05-25T07:07:38Z"
    message: replset-0
    status: "True"
    type: userClusterAdmin
  currentInfo:
    members: 4
    resources:
      limits:
        cpu: "2"
        memory: 512Mi
      requests:
        cpu: "1"
        memory: 512Mi
  currentRevision: multicloudmongodb-sample-666cb9cb8
  replset:
  - _id: 0
    health: 1
    name: 10.29.5.103:33498
    state: 2
    stateStr: SECONDARY
    syncSourceHost: 10.29.5.107:38640
    syncingTo: 10.29.5.107:38640
  - _id: 1
    health: 1
    name: 10.29.5.103:38640
    state: 1
    stateStr: PRIMARY
    syncSourceHost: ""
    syncingTo: ""
  - _id: 2
    health: 1
    name: 10.29.5.107:38640
    state: 2
    stateStr: SECONDARY
    syncSourceHost: 10.29.5.103:38640
    syncingTo: 10.29.5.103:38640
  - _id: 3
    health: 1
    name: 10.29.5.103:37661
    state: 2
    stateStr: SECONDARY
    syncSourceHost: 10.29.5.107:38640
    syncingTo: 10.29.5.107:38640
  - _id: 4
    health: 1
    name: 10.29.5.103:35880
    state: 2
    stateStr: SECONDARY
    syncSourceHost: 10.29.5.107:38640
    syncingTo: 10.29.5.107:38640
  state: Running

Community

With the increasing demand for cross-cloud distribution and automated operation and maintenance capabilities of stateful services, exploring and practicing solutions around this scenario will become more meaningful.

Now, the cloud native federation middleware - FedState project has been open-sourced on Github. Developers who are interested in stateful services in multi-cloud and federation scenarios are welcome to experience and try it out. We also welcome everyone to participate and contribute together.

Repo url: https://github.com/fedstate/fedstate

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