openstack team mailing list archive

[Jay Pipes <jaypipes@xxxxxxxxx>]

On Mon, Feb 7, 2011 at 2:46 PM, Eric Day <eday@xxxxxxxxxxxx> wrote:
> Perhaps we can be a bit more explicit about what the performance
> issues will be. From your original email, you listed a few queries
> with an example "X-Y-Z" string for the account ID. My answer to
> those concerns is to let an account plugin parse that string that
> recognizes the format and structure the SQL/LDAP/... backend to make
> queries for those IDs efficient.

You are thinking about it in the wrong "direction".  You're talking
about Nova asking an auth plugin for authorization information. I'm
talking about something entirely the opposite direction: plugins
asking *Nova* for information attached to a group of entities. If we
go down this proposed route, then Nova will have no way to efficiently
query its data stores for queries from plugins such as:

For example, assume this example scenario:

An organization uses the following structure:

Rackspace -> Reseller A -> Customer B -> Project X

if a billing plugin wants to find all usage records for Customer B, it needs to:

* Query its internal data store for all projects at Customer B
* For each project in list, issue a request to Nova's (as yet
undefined) usage/audit API. Something like this would be executed by
the plugin:

account_id = "rackspace-resellerA-customerB"
customer_id = account_id.split('-')[-1]
projects = get_list_of_projects_for_customer(customer_id)
records = []
for project in projects:
    account_string = account_id + '-' + project
    records.append(nova.client.do_request('GET',
'/usage/by-account-id/%s' % account_string))

This is, of course, perfectly fine, but I think you can agree with me
that this is far from efficient.  Assume Customer B has 100 projects
(not unreasonable for a reseller-type organization). That is 100
requests to Nova's usage/audit API. And 100 SQL queries against the
Nova data store(s).

What I'm saying is that by adding a flexible org schema to Nova's data
store would allow the whole thing to be done in a single request to
the Nova usage/audit API:

GET /usage/by-account-id/customerB?include_children=1

With the include_children=1 param signalling to Nova to do a nested
sets query against the organization schema.

1 query instead of 100.

I hope that explains the performance difference adequately.

Now, that said, punting this to the external plugin system and
adapting the existing projects table to support multiple networks is
the simplest and shortest solution. I was just pointing out that this
solution, while simple, can lead to inefficiencies in the long run.

I also know that you are pushing hard for a fully-distributed data
store for Nova, and that distributed data storage would at least
mitigate some of the inefficiency concerns (because the distributed
data store would force the 100 queries anyway...).

But, I wanted to air my concerns about efficient querying of this kind
of data up front.

Cheers,

jay

> Let's use the term 'entity' for 'account'. An entity could also be
> a project or some other org node.
>
> If we step back and look at what Nova needs from such an API, it's
> really just "authenticate with ID X and token Y", and if successful you
> get back a list of entities that the requested ID is part of (perhaps
> an 'account' and 'project', but those are deployment-specific terms).
>
> For simple deployments with no account structure, an ID may just be
> a direct entity reference, and the returned entity list contains a
> single entity for the ID.
>
> The account plugin layer will convert the given ID to the list of
> entities by parsing the string and performing an efficient lookup
> specific to the format/deployment. The existence of a returned
> entity may be sufficient for authz purposes alone, or we may attach
> project-specific key/value pairs or a comma separate list value that
> can store more fine-grained permissions per entity (CRUD flags). I'm
> thinking this would be kept this opaque in the backend account system
> (generic metadata per project), and interpreted when loaded in the
> nova auth/account plugins to give efficient matching operations.
>
> The nova.context object would then have a list of entities that can
> be used for all authorization requests, for example, if an instance
> belongs to entity A and B (where A may be a user and B may be a project
> in this deployment), then operations are verified against the list
> of context entities to ensure one of them allows it. This is pretty
> much how it works today, just replacing 'user' and 'project' columns
> on resources with an arbitrary mapping of entities per resource.
>
> What are some other specific queries that Nova or other projects need
> to make that you feel would be inefficient or would result in hacks?
>
> -Eric
>
> On Mon, Feb 07, 2011 at 12:57:09PM -0500, Jay Pipes wrote:
>> I give up trying to explain why I think this will lead to suboptimal
>> performance and hacks all over the external ecosystem.
>>
>> If the decision is to punt and let the external "auth systems" be
>> responsible for understanding the relationships between accounts and
>> users in Nova, so be it.
>>
>> I'll just predict the performance issues up front and call it a day.
>>
>> Cheers,
>> jay
>>
>> On Mon, Feb 7, 2011 at 12:46 PM, Eric Day <eday@xxxxxxxxxxxx> wrote:
>> > On Mon, Feb 07, 2011 at 08:50:28AM -0500, Jay Pipes wrote:
>> >> No, I think you've missed my point. Comments inline...
>> >
>> > Actually, I think I did get all your points, we're just not connecting
>> > somewhere. :)
>> >
>> >> On Mon, Feb 7, 2011 at 12:35 AM, Eric Day <eday@xxxxxxxxxxxx> wrote:
>> >> > 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.
>> >>
>> >> I wasn't talking at all about auth. Accounts != auth. Accounts are a
>> >> way to group users and groups of users in order to assign arbitrary
>> >> attributes to that group of things (think: billing attributes, policy
>> >> attributes (like preference of networking topology, quality of
>> >> service, etc)).
>> >
>> > I think we need to push accounts, authz, authc, access
>> > control, ... into the auth/accounts API (nova.auth). Actually,
>> > openstack-common/auth, but that's another email. :)
>> >
>> > We can structure the account objects returned by this API to
>> > provide all the information we need, and then allow limited update
>> > functionality on them. You want to be using your orgs auth-system API
>> > to manage that data, not Nova's API. The openstack accounts API just
>> > peeks into it getting all the information it needs.
>> >
>> >> Having an opaque account identifier in Nova means that Nova is
>> >> essentially "giving up" on trying to have an efficient, standardized
>> >> query interface for accounts. If this is what is wanted, so be it, but
>> >> I think I adequately pointed out the efficiency problems of that
>> >> approach.  More below...
>> >
>> > Yes and no. Nova should not have this, an account management system
>> > should. Nova (and other projects) needs an API into this that returns
>> > objects that works for our various use cases. For example, at the authc
>> > step, you may get back a list of entity objects that represent all
>> > the users/groups/whatever it maps to (or possibly a single aggregate
>> > object), and you may have some generic, limited operations on those
>> > objects that can write back to the pluggable store. Think of this
>> > mostly as a read-only API.
>> >
>> >> > The examples below
>> >> > where you have 'X-Y-Z' format is assuming a certain structure/layout,
>> >>
>> >> Ah, and this is where you would be incorrect.  The SQL structure I
>> >> specified can accomodate virtually any structure, not just X-Y-Z, and
>> >
>> > Ok, when you were doing prefix/suffix matching searches, that was
>> > assuming something, but if those SQL queries were meant to be behind
>> > an auth plugin, then n/m. :)
>> >
>> > My main point is this could be a big base64 string, a comma-separated
>> > entity list, a number, a snowman, anything.
>> >
>> >> that's why I was proposing it.  Having a string-based all-in-one key
>> >> actually forces Nova to expose an API that doesn't know how to query
>> >> for information properly. Like I said, if the decision is for ALL
>> >> account "stuff" to be handled externally, then Nova shouldn't even
>> >> have an API to get information via account, since it doesn't know what
>> >> an account actually is. If the "external only" is the decision, then
>> >
>> > That's what I am proposing, nova-core shouldn't concern itself with
>> > stats, billing, reporting, and advanced user management. I agree with
>> > Swift's approach.
>> >
>> >> you might as well just add a field to the projects table called
>> >> "account_tag", make it a TEXT field, and have it output as-is in the
>> >> data retrieval APIs. The one-network-per-project is a wholly separate
>> >> issue that can be addressed by reworking the networking code to allow
>> >> "projects" to have multiple networks, but, as I said in the original
>> >> post, I think the whole concept of a project in Nova right now is too
>> >> restrictive and could be replaced by the model I showed.
>> >>
>> >> > 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).
>> >>
>> >> Again, this has nothing to do with auth at all.
>> >
>> > I was assuming auth/accounts were wrapped up in the same API. So call
>> > it openstack accounts API, which also manages auth*.
>> >
>> >> The root of the issue is the projects table in Nova. It only works for
>> >> the most basic organizational structure. If it could be
>> >> adapted/replaced by a model that can represent a much wider range of
>> >> organizational structures, that would be my ideal solution.
>> >
>> > Yes, it needs to go, and I think the structure you provide is along
>> > the lines of what we need to do with account objects in code. Just turn
>> > your proposed SQL tables into Python classes and put a well-defined API
>> > around it so it can be backed by anything and we'll be in agreement. We
>> > don't want to tie ourselves to SQL, as it should not be first class
>> > (LDAP, NoSQL, ...).
>> >
>> > -Eric
>> >
>> >>
>> >> -jay
>> >>
>> >> > -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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