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Message #00460
Re: Pondering multi-tenant needs in nova.
+1
________________________________________
From: openstack-bounces+sandy.walsh=rackspace.com@xxxxxxxxxxxxxxxxxxx [openstack-bounces+sandy.walsh=rackspace.com@xxxxxxxxxxxxxxxxxxx] on behalf of Eric Day [eday@xxxxxxxxxxxx]
Sent: Monday, February 07, 2011 1:35 AM
To: Jay Pipes
Cc: openstack@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Openstack] Pondering multi-tenant needs in nova.
I disagree with your disagreement. :)
When we have string based ID's like this, it doesn't need to translate
directly into a varchar column for operations. First, auth data may not
be stored as SQL at all for some systems and could be broken out into
key/value pairs with some indexed. It could also translate directly
into a LDAP hierarchy which can be tuned to be very efficient. For
SQL-based auth storage, this could remain pluggable according to the
how the organization creates the string. For example, the string may
be broken out into parts for the auth lookup and mapped to various
columns/tables to search/join together efficiently. The examples below
where you have 'X-Y-Z' format is assuming a certain structure/layout,
but I think we should treat the string as completely opaque outside the
auth plugins and let the auth plugins perform optimized translation
and lookup into auth and access control objects that are used in the
rest of the code for the various projects (much like it is today).
-Eric
On Sun, Feb 06, 2011 at 09:57:56AM -0500, Jay Pipes wrote:
> Strongly disagree, but nicely, of course :)
>
> I'll disagree by showing you an example of why not having a queryable
> org model is problematic:
>
> Let's say we go ahead and do what Glen suggests and have a string
> account ID that is then attached to the user in a one to many
> relationship.
>
> In SQL (MySQL variant below), this is represented as so:
>
> # Our existing users table:
> CREATE TABLE users (
> id VARCHAR(255) NOT NULL PRIMARY KEY,
> access_key VARCHAR(255) NOT NULL,
> secret_key VARCHAR(255) NOT NULL,
> is_admin TINYINT NOT NULL DEFAULT 0
> );
>
> # Proposed accounts table, with string based tag-like account identifier:
> CREATE TABLE accounts (
> id VARCHAR(255) NOT NULL PRIMARY KEY,
> user_id VARCHAR(255) NOT NULL,
> FOREIGN KEY fk_users (user_id) REFERENCES users (id)
> );
>
> Now let's say that we store account IDs like this: enterprise-dept-milestone.
>
> How would we get all accounts in Enterprise X? Easy, and efficiently:
>
> SELECT id FROM accounts WHERE id LIKE "X%"
>
> How would we get all accounts in Enterprise X and Dept Y? Again, it
> would be easy and efficient:
>
> SELECT id FROM accounts WHERE id LIKE "X-Y-%"
>
> But, what happens if multiple departments can work on the same
> milestone (a common requirement)?
>
> How do we query for all accounts in Enterprise X and Milestone Z?
>
> The SQL would be horrific, and with millions of records, would bog the
> reporting system down (trust me):
>
> SELECT id FROM accounts WHERE id LIKE "X%-%-%Z".
>
> The above query would force a full table scan across the entire
> accounts table. An organization like Rackspace would theoretically
> have millions of account records (# customers + (# customers X
> #customer "projects") + (# resellers X # reseller customers) + (#
> reseller customers X # reseller customer "projects"))
>
> The "simpler" query of getting all accounts working on a milestone now
> becomes equally inefficient:
>
> SELECT id FROM accounts WHERE if LIKE "%-Z"
>
> The above query also has the side-effect of introducing subtle bugs
> when, and this will happen because of Murphy's law, accounts called
> "Rackspace-Accounting" and "Rackspace-IT-Accounting" are created.
> Now, the account for the accounting department and the IT department's
> "Accounting" milestone are erroneously returned.
>
> While it may seem nice and easy to put string-based, loose tags into
> the system, this decision is extremely difficult to reverse when made,
> and it leads to inefficiencies in the querying of the system and
> subtle query bugs as noted above.
>
> A more robust way of structuring the schema is like so, again in the
> MySQL SQL variant:
>
> # Our existing users table:
> CREATE TABLE users (
> id VARCHAR(255) NOT NULL PRIMARY KEY,
> access_key VARCHAR(255) NOT NULL,
> secret_key VARCHAR(255) NOT NULL,
> is_admin TINYINT NOT NULL DEFAULT 0
> );
>
> # Organizations are collections of users that can contain other organizations
> CREATE TABLE organization (
> id INT NOT NULL NOT NULL PRIMARY KEY,
> user_id VARCHAR(255) NOT NULL,
> parent INT NULL, # Adjacency list model enables efficient child and
> parent lookups
> left INT NULL, # left and right enable the nested sets model that enables
> right INT NULL, # equally efficient lookups of more complex relationships
> FOREIGN KEY fk_users (user_id) REFERENCES users (id)
> );
>
> The above structure can accomodate both simple (get my immediate
> parent or immediate children) queries and complex queries (get ALL my
> children, aggregate querying across the entire tree or subtrees) and
> do so efficiently. The query API interface that we expose via Nova
> (that would be consumed by some reporting/audit/management tools)
> would therefore not be a serious drain on the databases storing Nova
> data.
>
> More information on the adjacency list and nested sets models are
> available here:
>
> http://en.wikipedia.org/wiki/Nested_set_model
> http://en.wikipedia.org/wiki/Adjacency_list_model
>
> I'd highly recommend this solution as opposed to the seemingly simple
> tag-based solution that leads to gross querying inefficiencies and
> subtle bugs.
>
> Just my two cents.
>
> -jay
>
> On Thu, Feb 3, 2011 at 7:38 PM, John Purrier <john@xxxxxxxxxxxxx> wrote:
> > I think Glen is on the right track here. Having the account_ID be a string
> > with no connotation for Nova allows two benefits: 1) deployments can create
> > the arbitrary organizational models that fit their particular DC, physical,
> > and logical structures, and 2) the Nova code is simpler as the hierarchical
> > concepts do not have any manifestations in the code.
> >
> >
> >
> > Additional benefit includes an easier mapping to the particular identity and
> > authorization system that a deployment chooses to use.
> >
> >
> >
> > John
> >
> >
> >
> > From: openstack-bounces+john=openstack.org@xxxxxxxxxxxxxxxxxxx
> > [mailto:openstack-bounces+john=openstack.org@xxxxxxxxxxxxxxxxxxx] On Behalf
> > Of Glen Campbell
> > Sent: Thursday, February 03, 2011 2:42 PM
> > To: Devin Carlen; Monsyne Dragon
> > Cc: openstack@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Openstack] Pondering multi-tenant needs in nova.
> >
> >
> >
> > I think that this could be done in the current proposal. Specifically, the
> > account_id is an arbitrary string that is generated externally to Nova. You
> > could, for example, easily identify an organizational hierarchy. For
> > example, an accountID could be:
> >
> >
> >
> > enterprise-org-project-milestone
> >
> >
> >
> > From Nova's point of view, it makes no difference, so long as that string is
> > associated with a usage event and regurgitated when reported. The cloud
> > administrator can interpret it however it chooses. For simple organizations,
> > it could be identical to the project_id, or even just blank. The project_id
> > holds the network information, and the account_id tracks the usage and other
> > notifications.
> >
> >
> >
> > There's no good reason for Nova to have to model an organization internally;
> > it certainly wouldn't match all the possible org structures available.
> >
> >
> >
> >
> >
> >
> >
> > From: Devin Carlen <devin.carlen@xxxxxxxxx>
> > Date: Thu, 3 Feb 2011 12:02:38 -0800
> > To: Monsyne Dragon <mdragon@xxxxxxxxxxxxx>
> > Cc: <openstack@xxxxxxxxxxxxxxxxxxx>
> > Subject: Re: [Openstack] Pondering multi-tenant needs in nova.
> >
> >
> >
> > We were just talking about this the other day. We definitely need some kind
> > of further hierarchy. I think a typical kind of use case for multi-tenant
> > could be something like:
> >
> >
> >
> > Enterprise contains Organizations
> >
> >
> >
> > Organizations contain Organizations and Projects
> >
> >
> >
> > Projects contain Instances, etc.
> >
> >
> >
> >
> >
> > In this structure enterprise is just a top level organization. If we
> > structure it this way it would make metering and billing pretty simple.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > On Feb 2, 2011, at 5:37 PM, Monsyne Dragon wrote:
> >
> >
> >
> > I am sorting out some possible implementations for the
> > multi-tenant-accounting blueprint, and the related system-usage-records bp,
> > and I just wanted to run this by anyone interested in such matters.
> >
> > Basically, for multitenant purposes we need to introduce the concept of an
> > 'account' in nova, representing a customer, that basically acts as a label
> > for a group of resources (instances, etc), and for access control (i.e
> > customer a cannot mess w/ customer b's stuff)
> >
> > There was some confusion on how best to implement this, in relation to
> > nova's project concept. Projects are kind of like what we want an account
> > to be, but there are some associations (like one project per network) which
> > are not valid for our flat networking setup. I am kind of straw-polling on
> > which is better here:
> >
> > The options are:
> > 1) Create a new 'account' concept in nova, with an account basically being
> > a subgroup of a project (providers would use a single, default project, with
> > additional projects added if needed for separate brands, or resellers, etc),
> > add in access control per account as well as project, and make sure
> > apis/auth specify account appropriately, have some way for a default
> > account to used (per project) so account doesn't get in the way for
> > non-multitenant users.
> >
> > 2) having account == nova's "project", and changing the network
> > associations, etc so projects can support our model (as well as current
> > models). Support for associating accounts (projects) together for
> > resellers, etc would either be delegated outside of nova or added later
> > (it's not a current requirement).
> >
> > In either case, accounts would be identified by name, which would be an
> > opaque string an outside system/person would assign, and could structure to
> > their needs (ie. for associating accounts with common prefixes, etc)
> >
> > --
> >
> > --
> > -Monsyne Dragon
> > work: 210-312-4190
> > mobile 210-441-0965
> > google voice: 210-338-0336
> >
> >
> >
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If you receive this transmission in error, please notify us immediately by e-mail
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