Overall my thinking is - When somebody wants to customize creation of SSLEngine, most likely they are more expert in dealing with SSL domain related stuff than "Kafka's reconfigurability" aspect. As a custom implementation it makes more sense to me to say - Hey I'll control how I initialize my SSL context/engine and btw if Kafka can give me a way to just get re-created whenever some set of config keys changes, it is great! This is similar to my thinking on KIP-486 which is- as a Kafka operator I am just trying to be compliant to my company's security policies to load keys/certs in certain way. For that, I should not be penalized by Kafka to know all about Java security Providers and how to really create SSLContext object etc given Java already provides a way to feed in KeyStore object regardless of how I load it.
On Thu, Sep 19, 2019 at 10:57 PM Maulin Vasavada <maulin.vasav...@gmail.com> wrote: > Hi Clement > > There will be good amount of state in the SslEngineFactory's default > implementation. Hence I feel we might anyway have a chaperon class to > provide reconfigurable functionality and will have one more class to host > the state/behavior of actual SSLContext/SSLEngine creation. While doing the > internal rewrite (so far two times) both of the times I reached to the same > conclusion.I feel if we leave the reconfigurations to the implementation - > it will repeat the same pattern of having two classes to manage it - since > most likely they will also have similar state information. Instead keep > that reconfigurations in SslFactory as is today and just allow "plugin of > creation of SSLEngine". > > One note I would like to make is: You are comparing this to MetricReporter > but we have to keep in mind that SSL configuration is inherently more > complex than a MetricReporters functionality. There are no JSSE equivalent > documents needed to be written for MetricReporter for example. So what > works best for simpler solutions may not work equally well for more complex > scenarios. > > > Thanks > Maulin > > > On Thu, Sep 19, 2019 at 8:36 PM Pellerin, Clement < > clement_pelle...@ibi.com> wrote: > >> We will get there eventually but I need to address another point first. >> >> My goal is to do exactly what the "other extension points with >> reconfigurable custom configs" are doing unless there is a good reason not >> to. They provide a ready-made solution that will let us reuse code, avoid >> pitfalls and show consistency. >> >> So far the roadblocks are >> - the need to enforce mandatory compatibility checks for the keystores >> and SSL handshake >> - SslFactory is used in two channel builders. >> >> Both of these roadblocks can be overcome by moving the checks to a new >> common base class of SslChannelBuilder and SaslChannelBuilder. This is easy >> since both classes extend Object directly. The new base class is not a >> public API so any implementation will do. The chaperon class SslFactory >> disappears and the interface extends Reconfigurable. >> >> Does this proposal address all the reasons you had not to do exactly what >> other extension points are doing? >> >> -----Original Message----- >> From: Maulin Vasavada [mailto:maulin.vasav...@gmail.com] >> Sent: Thursday, September 19, 2019 10:21 PM >> To: dev@kafka.apache.org >> Subject: Re: [DISCUSS] KIP-519: Make SSL context/engine configuration >> extensible >> >> Hi Clement >> >> So assuming there are two classes - SslFactory and SslEngineFactory like I >> suggested in my detailed post before this, we can use >> config.getConfiguredInstance() in SslFactory for SslEngineFactory class >> configuration and then followed by init() method. I don't see a challenge >> there. Can you please provide your input on my detailed post along with >> this recent point I am making? >> >> Thanks >> Maulin >> >> On Thu, Sep 19, 2019 at 5:04 PM Maulin Vasavada < >> maulin.vasav...@gmail.com> >> wrote: >> >> > Hi Clement, >> > >> > Thanks for pointing to AbstractConfig. Now I understand what you were >> > saying. I'll respond by tonight with more thoughts. >> > >> > Thanks >> > Maulin >> > >> > On Thu, Sep 19, 2019 at 5:46 AM Pellerin, Clement < >> > clement_pelle...@ibi.com> wrote: >> > >> >> I appreciate the effort you put into this. >> >> >> >> Lets do this in steps. You had a question on getConfiguredInstance(). >> >> >> >> The method getConfiguredInstance(key, Class) implemented in >> >> AbstractConfig is how the MetricsReporter and other extension points >> are >> >> intantiated. Creating the extension point this way calls the default >> >> constructor which is good. Since the (Re)Configurable interface >> dictates >> >> the signature of the configure() method, that forces the addition of a >> new >> >> init(...) method to pass the other constructor arguments. >> >> >> >> Do we agree on that before we move on to other issues? >> >> >> >> -----Original Message----- >> >> From: Maulin Vasavada [mailto:maulin.vasav...@gmail.com] >> >> Sent: Wednesday, September 18, 2019 4:37 PM >> >> To: dev@kafka.apache.org >> >> Subject: Re: [DISCUSS] KIP-519: Make SSL context/engine configuration >> >> extensible >> >> >> >> Hi Clement >> >> >> >> Here are my thoughts based on my latest re-write attempt and learnings, >> >> >> >> 1. I think that it will be a great value to keep both classes separate >> - >> >> SslFactory and SslEngineFactory and having method >> reconfigurableConfigs() >> >> in the SslEngineFactory. Here is the reasoning, >> >> >> >> a. It is kind of a Decorator pattern to me - even without named like >> one >> >> SslFactory is acting as a decorator/surrogate to the SslEngineFactory >> and >> >> helping it get created and re-created as needed based on the >> >> terms/conditions specified by SslEngineFactory (via >> >> reconfigurableConfigs() >> >> method) >> >> >> >> b. SslEngineFactory will be pluggable class. By keeping the SslFactory >> >> reconfigurable with delegation of reconfigurableConfigs() to >> >> SslEngineFactory it allows the implementation of SslEngineFactory to be >> >> worry free of - How Kafka manages reconfigurations. The contract is - >> >> Kafka's SslFactory will ask the implementation to provide which >> >> configurations it is ready to be reconfigured for. Rest of the logic >> for >> >> triggering and reconfiguring and validation is in SslFactory. >> >> >> >> c. The current validation in SslFactory about inter-broker-ssl >> handshake >> >> AND verifying that certificate chain doesn't change via dynamic config >> >> changes is rightly owned by SslFactory. We should not give flexibility >> to >> >> SslEngineFactory to decide if they want that validation or not. >> >> >> >> d. If SslEngineFactory fails to be re-created with new dynamic config >> >> changes the constructor will throw some exception and the SslFactory >> will >> >> fail the validateReconfiguration() call resulting in no-change. Hence >> the >> >> validation if the new config is right is still controlled by the >> >> SslEngineFactory without necessarily having explicit validate method >> >> (assuming if you had a point about - we should keep validation of >> changed >> >> configs in the pluggable class) >> >> >> >> >> >> 2. About the keystore validation in SslFactory - as I mentioned in >> above >> >> points, >> >> >> >> a. I feel it is Kafka's policy that it wants to mandate that validation >> >> regardless of the SslEngineFactory's implementation. I feel that >> >> regardless >> >> of customized implementation it is doing a 'logical' enforcement. I >> don't >> >> see many cases where you will end up changing certificate chain (I >> can't >> >> say the same about SANs entries though. see my below points). Hence >> that >> >> validation is reasonable to be generally enforced for dynamic config >> >> changes. If you change something violating that validation, you can >> avoid >> >> making such changes via dynamic configuration and do a rolling >> restarts of >> >> the boxes. >> >> >> >> b. If the implementation doesn't use keystore then automatically no >> >> validation will happen. Hence I don't see any issue with >> >> SslEngineFactory's >> >> implementations not having requirement to use keystores. >> >> >> >> c. There could be an argument however about - what it validates >> currently >> >> and is there a scope of change. Example: It validates SANs entries and >> >> that >> >> to me is a challenge because I have had scenarios where I kept adding >> more >> >> VIPs in my certs SANs entries without really changing any certificate >> >> chain. The existing validation will fail that setup unnecessarily. >> Given >> >> that - there could be change in SslFactory but that doesn't still make >> >> that >> >> validation eligible to go to SslEngineFactory implementations. >> >> >> >> >> >> 3. I am still in two minds about your point on - not using existing SSL >> >> Reconfigurable configs to be used by SslFactory on top of >> >> SslEngineFactory's reconfigurable configs. The reason for that is- >> >> >> >> a. I agree with you on that we should not worry about existing SSL >> >> reconfigurable configs in new changed code for SslFactory. Why depend >> on >> >> something you really don't need. However, Rajini's point is- if we >> decide >> >> to add more configs in the SSL reconfigurable configs which may be >> common >> >> across SslEngineFactory's implementations, it will make it easier. >> Again, >> >> just to make it easier we should not do it upfront. So now you see why >> I >> >> am >> >> double minded on it while more leaning toward your suggestion. >> >> >> >> 4. I think I totally miss what you refer by >> >> config.getConfiguredInstance(key, Class). Which Kafka existing class >> you >> >> are referring to when you do that? Do we have that in KafkaConfig? If >> you >> >> can clarify me on that I can think more about your input on it. >> >> >> >> 5. Now above all means- >> >> >> >> a. We will have createEngine(), reconfigurableConfigs(), keystore(), >> >> truststore() methods in the SslEngineFactory interface. However the >> return >> >> type for keystore and truststore method can't be existing >> SecurityStore. >> >> For that I already thought of the replacement with KeystoreHolder class >> >> which only contains references to java's KeyStore object and Kafka's >> >> Password object making it feasible for us to return non-implementation >> >> specific return type. >> >> >> >> b. We didn't talk about shouldBeRebuilt() so far at all given other >> >> important conflicts to resolve. We will get to it once we can hash out >> >> other stuff. >> >> >> >> 6. On Rajini's point on 'push notifications' for client side code when >> the >> >> key/trust store changes, >> >> >> >> " - For client-side, custom SslEngineFactory implementations could >> >> reconfigure themselves, we don't really need SslFactory to be >> involved >> >> at all." >> >> >> >> I think I am missing something. If we just have SslEngineFactory >> >> reconfigure itself it will generate new SSLContext and in-turn new >> >> SSLEgnine but how will it communicate that to the ChannelBuilders? >> Don't >> >> they have to refresh the reference to the SslEngineFactory via >> >> SslFactory's >> >> reconfigure() method in order to pick up that change? >> >> >> >> >> >> Thanks >> >> Maulin >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> On Tue, Sep 17, 2019 at 4:49 AM Pellerin, Clement < >> >> clement_pelle...@ibi.com> >> >> wrote: >> >> >> >> > Good point about the two callers of SslFactory. We can move the >> >> SslEngine >> >> > validation to a separate class and call it in both places. That >> >> SslEngine >> >> > validation class would not be part of the public API and therefore we >> >> don't >> >> > need to fuss about its API. >> >> > >> >> > -----Original Message----- >> >> > From: Maulin Vasavada [mailto:maulin.vasav...@gmail.com] >> >> > Sent: Tuesday, September 17, 2019 2:28 AM >> >> > To: dev@kafka.apache.org >> >> > Subject: Re: [DISCUSS] KIP-519: Make SSL context/engine configuration >> >> > extensible >> >> > >> >> > Hi Clement/Rajini >> >> > >> >> > When I read your responses - I swing between both of your suggestions >> >> :) I >> >> > see both of your points. Let me ponder little bit more and give me >> take >> >> in >> >> > a day or so. >> >> > >> >> > I tend to agree with Clement in a sense that we need to define clear >> >> > responsibilities of classes. Right now I feel it's not clear. Also, I >> >> tend >> >> > to agree to both of you about keystore/truststore validation - the >> >> conflict >> >> > I've to propose a clean agreeable solution to. >> >> > >> >> > One clarification to Clement is - there are two classes using >> SslFactory >> >> > today - SslChannelBuilder and SaslChannelBuilder so we have to keep >> >> that in >> >> > mind. However, once we have clear responsibilities of classes, that >> >> should >> >> > automatically clear what goes where. >> >> > >> >> > Thanks >> >> > Maulin >> >> > >> >> >> > >> >
