Member Methods

They allow an administrator to configure a cluster, by changing the members of a cluster. The implementation for member methods follows the specification given in the etcd members Api.

getMembers

Gets a list of members of an etcd cluster and their details:

getMembers: Future[EtcdGetMembersResult]

Implemented according to etcd Members API: “List members”.

Returns a Future wrapped around either EtcdGetMembersResponse or EtcdStandardError extending EtcdGetMembersResult. .. _addMembers:

addMembers

Adds a member to an existing etcd cluster:

addMember(peerURLs: EtcdMemberForm): Future[EtcdAddMemberResult]

Implemented according to etcd Members API: “Add a member”.

Parameters:

• peerURLs: EtcdMemberForm containing a list of strings representing the peer URLs of the new member.

Returns a Future wrapped around either EtcdAddMemberResponse or EtcdStandardError extending EtcdAddMemberResult.

deleteMembers

Deletes a member form an etcd cluster:

deleteMember(peerID: String): Future[EtcdDefaultResult]

Implemented according to etcd Members API: “Delete a member”.

Parameters:

• peerID: A string identifying another member of the etcd cluster.

Returns a Future wrapped around either EtcdConfirmationResponse or EtcdStandardError extending EtcdConfirmationResult. .. _changePeerURLs:

changePeerURLs

Updates the peer URLs of a given member of an etcd cluster:

changePeerURLs(peerID: String, peerURLs: EtcdMemberForm): Future[EtcdDefaultResult]

Implemented according to etcd Members API: “Change the peer urls of a member”.

Parameters:

• peerID: A string identifying another member of the etcd cluster.
• peerURLs: EtcdMemberForm containing a list of strings representing the new peer URLs that will replace the old ones.

Returns aFuture wrapped around either EtcdConfirmationResponse or EtcdStandardError extending EtcdConfirmationResult.

A possible work flow

The following snippets of code are meant to be read linearly. Each depends on the previous one. They present subsequent operations using EtcdClient’s member methods.

We start by filling a EtcdMemberForm containing a list of peer URLs:

val newMemberForm: EtcdMemberForm =
  EtcdMemberForm(List("http://10.0.0.10:2380", "http://10.0.0.11:2380"))

When an addMember operation is performed using the form from above, we receive an id, which identifies the new member added:

val member: Future[String] = for {
  EtcdAddMemberResponse(headers, body) <- etcdcli.addMember(newMemberForm)
} yield body.id

We can verify that the member was added by listing the members of the cluster:

val getMembersReq: Future[EtcdGetMembersResult] = for {
  memberID <- member
  membersResp <- etcdcli.getMembers
} yield membersResp
val memberAdded: Future[Boolean] = member flatMap {member =>
getMembersReq.map{
  case EtcdGetMembersResponse(clusterId, body) =>
    // should be true
    body.members.contains(
      EtcdMember(member, "", List("http://10.0.0.10:2380", "http://10.0.0.11:2380"), List ())
      )
}
}

But now, suppose we want to change the peer URLs of the recently added member. We need to fill another EtcdMemberForm containing a list of peer URLs that will replace the previous peer URLs:

val changeMemberForm: EtcdMemberForm = EtcdMemberForm(List("http://10.0.0.12:4002"))

Next we perform a changePeerURLs operation. After that operation we perform a getMembers operation:

val changePeerURLReq: Future[EtcdGetMembersResult] = for{
  member <- member
  confirmation <- memberAdded
  changeUrls <- etcdcli.changePeerURLs(member, changeMemberForm)
  membersResp <- etcdcli.getMembers
} yield membersResp

The getMembers operation performed last can help us check that member‘s peer URLs have been modified:

val memberPeerURLsChanged: Future[Boolean] = member flatMap {member =>
  changePeerURLReq.map{
    case EtcdGetMembersResponse(clusterId, body) =>
      // should be true
      body.members.contains(EtcdMember(member, "", List("http://10.0.0.12:4002"), List()))
  }
}

Finally, suppose we want to delete the recently added member. In that case we need to perform a deleteMember operation:

val deleteMemberReq: Future[EtcdConfirmationResult] = for{
  member <- member
  deleteMember <- etcdcli.deleteMember(member)
} yield deleteMember

deleteMemberReq onSuccess{
  case EtcdConfirmationResponse(clusterID) =>
    //shouldBe a EtcdClusterId
    clusterID shouldBe a[EtcdClusterId]
}