b3a0be6eaa
This repo is now testing only with Python 3, so let's make a few cleanups: - Remove obsolete sections from setup.cfg - Update requirements, no need for python_version anymore - Switch to using sphinx-build, fix problems found - Use newer openstackdocstheme and Sphinx versions - Cleanup */source/conf.py to remove now obsolete content. - Remove install_command from tox.ini, the default is fine Change-Id: I6c593dff382a7aac4d758f802173f5a9f1e66182
311 lines
8.7 KiB
ReStructuredText
311 lines
8.7 KiB
ReStructuredText
..
|
|
This work is licensed under a Creative Commons Attribution 3.0 Unported
|
|
License.
|
|
|
|
http://creativecommons.org/licenses/by/3.0/legalcode
|
|
|
|
Sections of this template were taken directly from the Nova spec
|
|
template at:
|
|
https://github.com/openstack/nova-specs/blob/master/specs/juno-template.rst
|
|
|
|
..
|
|
This template should be in ReSTructured text. The filename in the git
|
|
repository should match the launchpad URL, for example a URL of
|
|
https://blueprints.launchpad.net/trove/+spec/awesome-thing should be named
|
|
awesome-thing.rst.
|
|
|
|
Please do not delete any of the sections in this template. If you
|
|
have nothing to say for a whole section, just write: None
|
|
|
|
Note: This comment may be removed if desired, however the license notice
|
|
above should remain.
|
|
|
|
|
|
========================================
|
|
Implement Couchbase cluster provisioning
|
|
========================================
|
|
|
|
Implement Couchbase cluster provisioning.
|
|
|
|
Launchpad Blueprint:
|
|
https://blueprints.launchpad.net/trove/+spec/couchbase-cluster-support
|
|
|
|
|
|
Problem Description
|
|
===================
|
|
|
|
Couchbase is by nature a distributed database.
|
|
Documents are distributed evenly across all nodes based on the hash of the
|
|
document key.
|
|
There are no query routers or configuration servers like in some other
|
|
databases (MongoDB).
|
|
Each document may have up to three replicas in addition to the active copy.
|
|
What this means is that there will be three extra copies of that data
|
|
within the cluster.
|
|
Couchbase clients are provided with an updated 'cluster map' which they use to
|
|
lookup data.
|
|
|
|
When a node gets added to the cluster the existing documents are incrementally
|
|
redistributed within the cluster (process also known as rebalancing).
|
|
Updated cluster maps are continuously provided to the clients.
|
|
Any active client connections should not be interrupted throughout the process.
|
|
|
|
When a node gets removed from the cluster the replicas on the other nodes
|
|
are promoted to the active and cluster maps updated so that the clients can
|
|
keep serving the requests. The promoted documents are then re-replicated within
|
|
the remaining nodes (rebalanced).
|
|
|
|
See `References`_ section for further details.
|
|
|
|
Proposed Change
|
|
===============
|
|
|
|
This specification proposes the following cluster-related actions:
|
|
|
|
* create
|
|
* grow
|
|
* shrink
|
|
* delete
|
|
* upgrade
|
|
|
|
Couchbase imposes cluster wide quota on the memory that get
|
|
evenly distributed between node services.
|
|
All nodes (including future nodes) need to be able to accommodate
|
|
this quota.
|
|
We therefore require the cluster to be homogeneous.
|
|
The quota size is configurable by 'cluster_ramsize_pc' Trove configuration as
|
|
the percentage of the total node RAM.
|
|
|
|
|
|
Create Cluster
|
|
--------------
|
|
|
|
* Provision a requested number of instances while initializing them as
|
|
Couchbase nodes (all nodes receive the same randomly generated Administrative
|
|
credentials from the API).
|
|
|
|
* Wait for the instances to become active.
|
|
|
|
* Execute cluster initialization on the first node (coordinator).
|
|
|
|
* Add the remaining nodes to the cluster via the coordinator node.
|
|
|
|
* Wait for the cluster rebalance to finish.
|
|
|
|
|
|
Grow Cluster
|
|
------------
|
|
|
|
* Retrieve the current Administrative credentials from the first
|
|
node (coordinator) of the existing cluster.
|
|
|
|
* Provision and initialize a requested number of instances as Couchbase nodes
|
|
with the current credentials (above).
|
|
|
|
* Wait for the instances to become active.
|
|
|
|
* Add the new nodes to the cluster via the coordinator node.
|
|
|
|
* Wait for the cluster rebalance to finish.
|
|
|
|
|
|
Shrink Cluster
|
|
--------------
|
|
|
|
* Load the removed instances.
|
|
|
|
* Select one of the remaining nodes and use it as the coordinator.
|
|
|
|
* Remove the nodes from the cluster via the coordinator.
|
|
|
|
* Wait for the cluster rebalance to finish.
|
|
|
|
* Delete decommissioned instances.
|
|
|
|
|
|
Configuration
|
|
-------------
|
|
|
|
The following configuration values will be implemented in the Couchbase
|
|
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.'
|
|
'couchbase.api.CouchbaseAPIStrategy',
|
|
help='Class that implements datastore-specific API logic.'),
|
|
cfg.StrOpt('taskmanager_strategy',
|
|
default='trove.common.strategies.cluster.experimental'
|
|
'.couchbase.taskmanager.CouchbaseTaskManagerStrategy',
|
|
help='Class that implements datastore-specific task manager '
|
|
'logic.'),
|
|
cfg.StrOpt('guestagent_strategy',
|
|
default='trove.common.strategies.cluster.experimental'
|
|
'.couchbase.guestagent.CouchbaseGuestAgentStrategy',
|
|
help='Class that implements datastore-specific Guest Agent API '
|
|
'logic.'),
|
|
cfg.IntOpt('cluster_ramsize_pc', default=80, min=0, max=80,
|
|
help='Per node RAM quota in for the Data service expressed as a'
|
|
' percentage of the available memory.'
|
|
' Minimum of 256MB will be used if the given percentage amounts'
|
|
' for less.'),
|
|
|
|
Database
|
|
--------
|
|
|
|
None
|
|
|
|
Public API
|
|
----------
|
|
|
|
None
|
|
|
|
Public API Security
|
|
-------------------
|
|
|
|
None
|
|
|
|
Python API
|
|
----------
|
|
|
|
None
|
|
|
|
CLI (python-troveclient)
|
|
------------------------
|
|
|
|
None
|
|
|
|
Internal API
|
|
------------
|
|
|
|
None
|
|
|
|
Guest Agent
|
|
-----------
|
|
|
|
The work will require some preliminary refactoring of the guest manager.
|
|
This may also include tasks such that:
|
|
|
|
- providing a common framework for executing Couchbase CLI calls
|
|
The guest-agent currently executes only two CLI commands hardcoded in
|
|
'system.py' file. We will need to execute a greater variety of commands.
|
|
This would include CouchbaseAdmin to execute CLI calls and handle results in
|
|
a generic way. It will also facilitate reducing 'system.py'
|
|
which we have been moving away from in other guests as well.
|
|
- making the ramsize quota relative to the node's total RAM
|
|
Couchbase 3 requires a parameter to cluster-init is RAMSIZE quota.
|
|
The valid value is between 256MB and 80% of available RAM.
|
|
Make the default % a Trove variable.
|
|
- using appropriate guestagent models for the Couchbase administrative user
|
|
Couchbase should be using it's own User model rather than relying on
|
|
generic MySQL-object.
|
|
|
|
The following methods will be implemented in the CouchbaseGuestAgentAPI::
|
|
|
|
def initialize_cluster(self):
|
|
LOG.debug("Configuring cluster parameters via node: %s" % self.id)
|
|
self._call("initialize_cluster",
|
|
guest_api.AGENT_HIGH_TIMEOUT, self.version_cap)
|
|
|
|
def get_cluster_password(self):
|
|
LOG.debug("Retrieving cluster password from node: %s" % self.id)
|
|
return self._call("get_cluster_password",
|
|
guest_api.AGENT_LOW_TIMEOUT, self.version_cap)
|
|
|
|
def get_cluster_rebalance_status(self):
|
|
LOG.debug("Retrieving status of current cluster rebalance via node: %s"
|
|
% self.id)
|
|
return self._call("get_cluster_rebalance_status",
|
|
guest_api.AGENT_LOW_TIMEOUT, self.version_cap)
|
|
|
|
def add_nodes(self, nodes):
|
|
LOG.debug("Adding nodes to the cluster: %s" % self.id)
|
|
self._cast('add_nodes', self.version_cap, nodes=nodes)
|
|
|
|
def remove_nodes(self, nodes):
|
|
LOG.debug("Removing nodes from the cluster: %s" % self.id)
|
|
self._cast('remove_nodes', self.version_cap, nodes=nodes)
|
|
|
|
def cluster_complete(self):
|
|
LOG.debug("Sending a setup completion notification for node: %s"
|
|
% self.id)
|
|
return self._call("cluster_complete", guest_api.AGENT_HIGH_TIMEOUT,
|
|
self.version_cap)
|
|
|
|
Alternatives
|
|
------------
|
|
|
|
None
|
|
|
|
|
|
Dashboard Impact (UX)
|
|
=====================
|
|
|
|
Will need to enable Couchbase as a clustering datastore.
|
|
|
|
|
|
Implementation
|
|
==============
|
|
|
|
Assignee(s)
|
|
-----------
|
|
|
|
Primary assignee:
|
|
Petr Malik <pmalik@tesora.com>
|
|
|
|
Milestones
|
|
----------
|
|
|
|
Ocata
|
|
|
|
Work Items
|
|
----------
|
|
|
|
The preliminary work in the guest manager and cluster strategy itself
|
|
may be delivered in two separate commits if it facilitates smoother review
|
|
process.
|
|
|
|
|
|
Upgrade Implications
|
|
====================
|
|
|
|
None
|
|
|
|
|
|
Dependencies
|
|
============
|
|
|
|
None
|
|
|
|
|
|
Testing
|
|
=======
|
|
|
|
* Manager unittests will be added where appropriate.
|
|
|
|
* The scenario tests already cover implemented functionality.
|
|
|
|
|
|
Documentation Impact
|
|
====================
|
|
|
|
Datastore documentation for Couchbase will need to be updated to reflect
|
|
clustering support.
|
|
|
|
|
|
References
|
|
==========
|
|
|
|
* Couchbase cluster management: http://docs.couchbase.com/admin/admin/Tasks/cluster-management.html
|
|
|
|
* Couchbase CLI reference: http://developer.couchbase.com/documentation/server/4.0/cli/cli-intro.html
|
|
|
|
* Couchbase cluster API: http://docs.couchbase.com/admin/admin/REST/rest-cluster-intro.html
|
|
|
|
|
|
Appendix
|
|
========
|
|
|
|
None
|