Redis Clustering

https://blueprints.launchpad.net/trove/+spec/redis-cluster

Redis is a NoSQL database designed for high performance caching and persistence of key/value data. This document outlines a proposal for implementing clustering for Redis.

Problem Description

Implement clustering for Redis.

Proposed Change

The Redis clustering feature will strive to implement the minimum functionality required for a user to implement a Redis cluster in a Trove environment. While Trove will provide functionality to support operations not possible directly through the Redis API, functionality will be left to the user to perform via the Redis API wherever possible. This decision is based on the belief that it would be extremely difficult to provide all the required functionality through a web interface, and that Redis users will be familiar with the Redis command set.

Configuration

The following configuration values will be implemented in the Redis configuration group:

cfg.BoolOpt('cluster_support', default=True,
            help='Enable clusters to be created and managed.'),
cfg.StrOpt('api_strategy',
           default='trove.common.strategies.cluster.experimental.'
           'redis.api.RedisAPIStrategy',
           help='Class that implements datastore-specific API logic.'),
cfg.StrOpt('taskmanager_strategy',
           default='trove.common.strategies.cluster.experimental.redis.'
           'taskmanager.RedisTaskManagerStrategy',
           help='Class that implements datastore-specific task manager '
                'logic.'),
cfg.StrOpt('guestagent_strategy',
           default='trove.common.strategies.cluster.experimental.'
           'redis.guestagent.RedisGuestAgentStrategy',
           help='Class that implements datastore-specific Guest Agent API '
                'logic.'),

Database

No changes.

REST API

Create Cluster

The cluster-create command will allow the user to create a cluster with the specified number of master nodes. The data slots will be evenly divided between the created nodes.

Request:

POST /v1.0/<tenant_id>/clusters
{
  "cluster": {
    "name": "redis-clstr",
    "datastore": {
      "type": "redis",
      "version": "3.0"
    },
    "instances": [
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      },
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      },
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      },
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      },
    ]
  }
}

Response:

{
  "cluster": {
    "id": "edaac9ca-b5e1-4028-adb7-fa7653e11224",
    "task": {
      "id": 2,
      "name": "BUILDING",
      "description": "Building the initial cluster."
    },
    "name": "redis-clstr",
    "created": "2015-01-29T20:19:23",
    "updated": "2015-01-29T20:19:23",
    "links": [{...}],
    "datastore": {
      "type": "redis",
      "version": "3.0"
    },
    "ip": [],
    "instances": [
      {
        "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
        "name": "redis-clstr-member-1",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
      {
        "id": "965ef811-7c1d-47fc-89f2-a89dfdd23ef2",
        "name": "redis-clstr-member-2",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
      {
        "id": "3642f41c-e8ad-4164-a089-3891bf7f2d2b",
        "name": "redis-clstr-member-3",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
      {
        "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
        "name": "redis-clstr-member-4",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
    ]
  }
}

HTTP Codes:

202 - Accepted.
400 - BadRequest. Server could not understand request.
403 - Forbidden. Local storage not specified in flavor ID: <ID>.
403 - Forbidden. A flavor is required for each instance in the cluster.
404 - Not Found. Flavor not found.

Grow Cluster

Adds nodes to a cluster. The added nodes will be master nodes empty of data and will have no slots assigned to them.

Request:

POST /v1.0/<tenant_id>/clusters/edaac9ca-b5e1-4028-adb7-fa7653e11224/action
{
    "grow": [
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      },
      {
        "flavorRef": "2",
        "volume": {
          "size": 2
        }
      }
    ]
}

Response:

{
  "cluster": {
    "id": "edaac9ca-b5e1-4028-adb7-fa7653e11224",
    "task": {
      "id": 2,
      "name": "BUILDING",
      "description": "Building the initial cluster."
    },
    "name": "redis-clstr",
    "created": "2015-01-29T20:19:23",
    "updated": "2015-01-29T20:19:23",
    "links": [{...}],
    "datastore": {
      "type": "redis",
      "version": "3.0"
    },
    "ip": [],
    "instances": [
      {
        "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
        "name": "redis-clstr-member-5",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
      {
        "id": "965ef811-7c1d-47fc-89f2-a89dfdd23ef2",
        "name": "redis-clstr-member-6",
        "status": "BUILD",
        "ip": [],
        "links": [{...}],
        "flavor": {
          "id": "2",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        }
      },
    ]
  }
}

HTTP Codes:

202 - Accepted.
400 - BadRequest. Server could not understand request.
403 - Forbidden. Local storage not specified in flavor ID: <ID>.
403 - Forbidden. A flavor is required for each instance in the cluster.
404 - Not Found. Flavor not found.

Shrink Cluster

Removes the specified nodes from the cluster. It is expected that all data slots have been removed from the node - the shrink operation will fail otherwise.

Request:

POST /v1.0/<tenant_id>/clusters/<cluster_id>/action
    "shrink": [
      {
        "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
      },
      {
        "id": "965ef811-7c1d-47fc-89f2-a89dfdd23ef2",
      }
    ]
}

Response:

N/A

HTTP codes:

202 - Accepted.
403 - Forbidden.  One or more nodes have data slots assigned.
404 - Not found.  Instance <id> does not exist.

Show Cluster

Request:

GET /v1.0/<tenant_id>/clusters/edaac9ca-b5e1-4028-adb7-fa7653e11224

Response:

{
  "cluster": {
    "id": "edaac9ca-b5e1-4028-adb7-fa7653e11224",
    "task": {
      "id": 1,
      "name": "NONE",
      "description": "No tasks for the cluster."
    },
    "name": "redis-clstr",
    "created": "2015-01-29T20:19:23",
    "updated": "2015-01-29T20:19:23",
    "links": [{...}],
    "datastore": {
      "type": "redis",
      "version": "3.0"
    },
    "ip": ["10.0.0.1", "10.0.0.2", "10.0.0.3", "10.0.0.4",],
    "instances": [
      {
        "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
        "name": "redis-clstr-member-1",
        "status": "ACTIVE",
        "ip": ["10.0.0.1"],
        "links": [{...}],
        "flavor": {
          "id": "7",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        },
      }
      {
        "id": "965ef811-7c1d-47fc-89f2-a89dfdd23ef2",
        "name": "redis-clstr-member-2",
        "status": "ACTIVE",
        "links": [{...}],
        "flavor": {
        "ip": ["10.0.0.2"],
          "id": "7",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        },
      },
      {
        "id": "3642f41c-e8ad-4164-a089-3891bf7f2d2b",
        "name": "redis-clstr-member-3",
        "status": "BUILD",
        "ip": ["10.0.0.3"],
        "links": [{...}],
        "flavor": {
          "id": "7",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        },
      },
      {
        "id": "3642f41c-e8ad-4164-a089-3891bf7f2d2b",
        "name": "redis-clstr-member-4",
        "status": "BUILD",
        "ip": ["10.0.0.4"],
        "links": [{...}],
        "flavor": {
          "id": "7",
          "links": [{...}]
        },
        "volume": {
          "size": 2
        },
      }
    ]
  }
}

HTTP Codes:

200 - OK.
404 - Not Found. Cluster not found.

Show Instance

Request:

GET /v1.0/<tenant_id>/clusters/edaac9ca-b5e1-4028-adb7-fa7653e11224/instances/416b0b16-ba55-4302-bbd3-ff566032e1c1

Response:

{
  "instance": {
    "status": "ACTIVE",
    "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
    "cluster_id": "edaac9ca-b5e1-4028-adb7-fa7653e11224",
    "name": "redis-clstr-member-1",
    "created": "2015-01-29T20:19:23",
    "updated": "2015-01-29T20:19:23",
    "links": [{...}],
    "datastore": {
      "type": "redis",
      "version": "3.0"
    },
    "ip": ["10.0.0.1"],
    "flavor": {
      "id": "7",
      "links": [{...}],
    },
    "volume": {
      "size": 2,
      "used": 0.17
    }
  }
}

HTTP Codes:

200 - OK.
404 - Not Found. Cluster not found.
404 - Not Found. Instance not found.

List Clusters

Request:

GET /v1.0/<tenant_id>/clusters

Response:

{
  "clusters": [
    {
      "id": "edaac9ca-b5e1-4028-adb7-fa7653e11224",
      "task": {
        "id": 1,
        "name": "NONE",
        "description": "No tasks for the cluster."
      },
      "name": "redis-clstr",
      "created": "2015-01-29T20:19:23",
      "updated": "2015-01-29T20:19:23",
      "links": [{...}],
      "datastore": {
        "type": "redis",
        "version": "3.0"
      },
      "instances": [
        {
          "id": "416b0b16-ba55-4302-bbd3-ff566032e1c1",
          "name": "redis-clstr-member-1",
          "links": [{...}],
        }
        {
          "id": "965ef811-7c1d-47fc-89f2-a89dfdd23ef2",
          "name": "redis-clstr-member-2",
          "links": [{...}],
        },
        {
          "id": "3642f41c-e8ad-4164-a089-3891bf7f2d2b",
          "name": "redis-clstr-member-3",
          "links": [{...}],
        },
        {
          "id": "3642f41c-e8ad-4164-a089-3891bf7f2d2b",
          "name": "redis-clstr-member-4",
          "links": [{...}],
        }
      ]
    },
    ...
  ]
}

HTTP Codes:

200 - OK.

Delete Cluster

Request:

DELETE /v1.0/<tenant_id>/clusters/<cluster_id>

Response:

N/A

HTTP codes:

202 - Accepted.
404 - Not found

Public API

No public API changes.

Public API Security

n/a

Python API

No Python API changes.

CLI (python-troveclient)

No CLI changes.

Internal API

No changes are envisioned to the guestagent api, beyond implementing the existing API methods.

Guest Agent

The following methods will be implemented in the RedisGuestAgentAPI:

def get_node_ip(self):
    LOG.debug("Retrieve ip info from node.")
    return self._call("get_node_ip",
                      guest_api.AGENT_HIGH_TIMEOUT, self.version_cap)

def get_node_id_for_removal(self):
    LOG.debug("Validating cluster node removal.")
    return self._call("get_node_id_for_removal",
                      guest_api.AGENT_HIGH_TIMEOUT, self.version_cap)

def remove_nodes(self, node_ids):
    LOG.debug("Removing nodes from cluster.")
    return self._call("remove_nodes", guest_api.AGENT_HIGH_TIMEOUT,
                      self.version_cap, node_ids=node_ids)

def cluster_meet(self, ip, port):
    LOG.debug("Joining node to cluster.")
    return self._call("cluster_meet", guest_api.AGENT_HIGH_TIMEOUT,
                      self.version_cap, ip=ip, port=port)

def cluster_addslots(self, first_slot, last_slot):
    LOG.debug("Adding slots %s-%s to cluster.", first_slot, last_slot)
    return self._call("cluster_addslots",
                      guest_api.AGENT_HIGH_TIMEOUT, self.version_cap,
                      first_slot=first_slot, last_slot=last_slot)

def cluster_complete(self):
    LOG.debug("Notifying cluster install completion.")
    return self._call("cluster_complete", guest_api.AGENT_HIGH_TIMEOUT,
                      self.version_cap)

Alternatives

n/a

Implementation

Assignee(s)

Primary assignee:
vgnbkr

Milestones

Target Milestone for completion:
Liberty-3

Work Items

  • implement clustering for Redis

implement new Taskmanager cluster strategy for Redis implement python API and shell for shrink/grow (this may be already done through cluster-scaling bp implementation) add grow/shrink to cluster strategy (in absence of scaling implementation) implement guest agent support for joining/leaving a cluster implement unit tests as appropriate implement int-test if the mechanism for doing so has been worked out by that time

Upgrade Implications

As this is a new implementation, no upgrade implications are envisioned.

Dependencies

Testing

  • Implementation of int-tests for clustering is still being worked out for MongoDB and Cassandra. It is expected that Redis will implement/run similar int-tests.

Documentation Impact

  • Datastore documentation for Redis will need to be updated to reflect clustering support.