I agree that it would be good to have more time to review and discuss
KIP-48.
Ismael
On Tue, Mar 8, 2016 at 12:55 AM, Gwen Shapira <g...@confluent.io> wrote:
> Hi Team,
>
> Since KIP-48 depends on KIP-43, which is already a bit of a risk for
> the next release - any chance we can delay delegation tokens to Kafka
> 0.10.1?
> With the community working on a release every 3 month, this is not a huge
> delay.
>
> Gwen
>
> On Fri, Feb 26, 2016 at 5:11 PM, Ashish Singh <asi...@cloudera.com> wrote:
> > Parth,
> >
> > Thanks again for the awesome write up. Following our discussion from the
> > JIRA, I think it will be easier to compare various alternatives if they
> are
> > listed together. I am stating below a few alternatives along with a the
> > current proposal.
> > (Current proposal) Store Delegation Token, DT, on ZK.
> >
> > 1. Client authenticates with a broker.
> > 2. Once a client is authenticated, it will make a broker side call to
> > issue a delegation token.
> > 3. The broker generates a shared secret based on HMAC-SHA256(a
> > Password/Secret shared between all brokers, randomly generated
> tokenId).
> > 4. Broker stores this token in its in memory cache. Broker also stores
> > the DelegationToken without the hmac in the zookeeper.
> > 5. All brokers will have a cache backed by zookeeper so they will all
> > get notified whenever a new token is generated and they will update
> their
> > local cache whenever token state changes.
> > 6. Broker returns the token to Client.
> >
> > Probable issues and fixes
> >
> > 1. Probable race condition, client tries to authenticate with a broker
> > that is yet to be updated with the newly generated DT. This can
> probably be
> > dealt with making dtRequest block until all brokers have updated
> their DT
> > cache. Zk barrier or similar mechanism can be used. However, all such
> > mechanisms will increase complexity.
> > 2. Using a static secret key from config file. Will require yet
> another
> > config and uses a static secret key. It is advised to rotate secret
> keys
> > periodically. This can be avoided with controller generating
> secretKey and
> > passing to brokers periodically. However, this will require brokers to
> > maintain certain counts of secretKeys.
> >
> > (Alternative 1) Have controller generate delegation token.
> >
> > 1. Client authenticates with a broker.
> > 2. Once a client is authenticated, it will make a broker side call to
> > issue a delegation token.
> > 3. Broker forwards the request to controller.
> > 4. Controller generates a DT and broadcasts to all brokers.
> > 5. Broker stores this token in its memory cache.
> > 6. Controller responds to broker’s DT req.
> > 7. Broker returns the token to Client.
> >
> > Probable issues and fixes
> >
> > 1. We will have to add new APIs to support controller pushing tokens
> to
> > brokers on top of the minimal APIs that are currently proposed.
> > 2. We will also have to add APIs to support the bootstrapping case,
> i.e,
> > when a new broker comes up it will have to get all delegation tokens
> from
> > the controller.
> > 3. In catastrophic failures where all brokers go down, the tokens will
> > be lost even if servers are restarted as tokens are not persisted
> anywhere.
> > If this happens, then there are more important things to worry about
> and
> > maybe it is better to re-authenticate.
> >
> > (Alternative 2) Do not distribute DT to other brokers at all.
> >
> > 1. Client authenticates with a broker.
> > 2. Once a client is authenticated, it will make a broker side call to
> > issue a delegation token.
> > 3. The broker generates DT of form, [hmac + (owner, renewer,
> > maxLifeTime, id, hmac, expirationTime)] and passes back this DT to
> client.
> > hmac is generated via {HMAC-SHA256(owner, renewer, maxLifeTime, id,
> hmac,
> > expirationTime) using SecretKey}. Note that all brokers have this
> SecretKey.
> > 4. Client then goes to any broker and to authenticate sends the DT.
> > Broker recalculates hmac using (owner, renewer, maxLifeTime, id, hmac,
> > expirationTime) info from DT and its SecretKey. If it matches with
> hmac of
> > DT, client is authenticated. Yes, it will do other obvious checks of
> > timestamp expiry and such.
> >
> > Note that secret key will be generated by controller and passed to
> brokers
> > periodically.
> > Probable issues and fixes
> >
> > 1. How to delete a DT? Yes, that is a downside here. However, this can
> > be handled with brokers maintaining a blacklist of DTs, DTs from this
> list
> > can be removed after expiry.
> > 2. In catastrophic failures where all brokers go down, the tokens will
> > be lost even if servers are restarted as tokens are not persisted
> anywhere.
> > If this happens, then there are more important things to worry about
> and
> > maybe it is better to re-authenticate.
> >
> >
> >
> > On Fri, Feb 26, 2016 at 1:58 PM, Parth Brahmbhatt <
> > pbrahmbh...@hortonworks.com> wrote:
> >
> >> Hi,
> >>
> >> I have filed KIP-48 so we can offer hadoop like delegation tokens in
> >> kafka. You can review the design
> >>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-48+Delegation+token+support+for+Kafka
> .
> >> This KIP depends on KIP-43 and we have also discussed an alternative to
> >> proposed design here<
> >>
> https://issues.apache.org/jira/browse/KAFKA-1696?focusedCommentId=15167800&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15167800
> >> >.
> >>
> >> Thanks
> >> Parth
> >>
> >
> >
> >
> > --
> >
> > Regards,
> > Ashish
>
