Thanks David. I agree pivoting this proposal around job update driven instructions would give us more incremental value for much less effort. I have researched and evaluated various Java and JSON diff libraries available under Apache license and could not find a reasonable solution that would give us exactly what we need. I started thinking about building a custom JSON diff java tool, which is certainly beyond the effort I hoped it would take.
With something like 'getJobUpdateInstructions(JobUpdateRequest r)' API we could immediately improve the client diff story by avoiding duplicate diff results. We would also be able to have something like '--dry-run' option on a 'aurora update start' command listing the affected instances and actions about to be taken. As for the actual TaskConfig diff details, this seems like a natural improvement we could add later when/if we find a better JSON diffing tool or dare to implement our own. Any thoughts/objections to the above? On Fri, Oct 2, 2015 at 1:29 PM, David McLaughlin <da...@dmclaughlin.com> wrote: > I'd like to propose an alternative - that we start off by having an API > endpoint which simply returns the JobUpdateInstructions that describes the > changes that would happen if a given JobUpdateRequest was applied. > > There is a lot of value in having clients ask the scheduler to tell them > what is going to happen rather than try and duplicate that diff algorithm > in both places. Of course this does not solve the "pretty" diff command > when trying to *display* the differences, but it does remove a lot of the > work in implementing the diff command and I think for the different types > of clients (UI/CLI/etc.) displaying the diffs is going to be a much bigger > problem anyway. > > In the future if the scheduler does calculate and return some > representation of the diff, I'd argue that it should be stored in > JobUpdateInstructions anyway, so we can always add that functionality later > and keep the APIs the same. > > Thanks, > David > > > On Wed, Sep 16, 2015 at 10:23 AM, Bill Farner <wfar...@apache.org> wrote: > >> I think it's fine to provide an 'enhanced' experience when the format is >> JSON, but i don't think we should force that. >> >> On Wed, Sep 16, 2015 at 10:22 AM, Maxim Khutornenko <ma...@apache.org> >> wrote: >> >> > The benefit of assuming a certain format is the richer experience we >> > can give to our users. The *blob* may be too large to make any sense >> > of it during diffing. I don't propose to enforce any schema though, >> > that would be too restrictive. I do however believe assuming JSON >> > format would be an acceptable tradeoff. >> > >> > Alternatively, we may allow non-JSON (e.g. binary) executor data blobs >> > and disabling JSON diffs for any executor types that don't follow the >> > guidance. This will result in a degraded user experience but may be >> > the middle ground here. Thoughts? >> > >> > On Tue, Sep 15, 2015 at 11:43 AM, <meghdoo...@yahoo.com.invalid> wrote: >> > > Isn't this data supposed to be any blob that transparently passes in to >> > the executor through mesos data blob. Why would we want to impose any >> sort >> > of format? It could be a binary blob. Executor writers should be able to >> > move between different schedulers/frameworks without any rework ideally. >> > This field seems like more like garbage in and garbage out and only >> > understood by end client and the executor. Scheduler may stay out of it. >> > > If you compute hash and indicate same or different data between 2 job >> > update diff, that may be reasonable. >> > > >> > > My 2 cents. >> > > >> > > Thx >> > > >> > > Sent from my iPhone >> > > >> > >> On Sep 15, 2015, at 11:01 AM, Zameer Manji <zma...@apache.org> wrote: >> > >> >> > >> I'm a proponent of firming up our executor <-> scheduler contract. >> > Since we >> > >> are going to get multiple executor support soon I think it would be >> > nice if >> > >> we said that ExecutorConfig.data was JSON. >> > >> >> > >> On Tue, Sep 15, 2015 at 10:47 AM, Maxim Khutornenko <ma...@apache.org >> > >> > >> wrote: >> > >> >> > >>> | I hope this doesn't mean we would be returning a textual >> > >>> representation of a diff >> > >>> >> > >>> If we can make an assumption that executor data is always JSON, we >> can >> > >>> deliver a much more specific answer by applying JSON diff tools. >> > >>> Something like: >> > >>> >> > >>> - "environment": "prod" >> > >>> + "environment": "test" >> > >>> >> > >>> Otherwise, we would have to output the entire ExecutorConfig.data >> blob >> > >>> content for both left and right sides and let users figure out the >> > >>> problem. I don't think that's acceptable. >> > >>> >> > >>> Does it make sense? Any suggestions on the output format of the diff? >> > >>> I think it should be structured but at the same time we have to get >> > >>> down to text level at some point to report concrete discrepancies. >> > >>> >> > >>>> On Mon, Sep 14, 2015 at 8:58 PM, Bill Farner <wfar...@apache.org> >> > wrote: >> > >>>> The 'blob'-iness of ExecutorConfig is intentional so that we can >> > support >> > >>>> alternative executors. I'd hate for that to go away. >> > >>>> >> > >>>>> On Mon, Sep 14, 2015 at 8:56 PM, Jake Farrell <jfarr...@apache.org >> > >> > >>>> wrote: >> > >>>> >> > >>>>> This is one of the hoops encountered when using the Thrift api >> > directly >> > >>> and >> > >>>>> not using the client, I'd love to see ExecutorConfig.data move to a >> > >>> thrift >> > >>>>> object and not be a string blob >> > >>>>> >> > >>>>> -Jake >> > >>>>> >> > >>>>> On Mon, Sep 14, 2015 at 9:28 PM, Bill Farner <wfar...@apache.org> >> > >>> wrote: >> > >>>>> >> > >>>>>> I like the idea of adding this API, but i don't see why it >> requires >> > >>> us to >> > >>>>>> make assumptions about ExecutorConfig.data. I hope this doesn't >> > mean >> > >>> we >> > >>>>>> would be returning a textual representation of a diff. Can you >> > >>> elaborate >> > >>>>>> on that? >> > >>>>>> >> > >>>>>> On Mon, Sep 14, 2015 at 4:14 PM, Maxim Khutornenko < >> > ma...@apache.org> >> > >>>>>> wrote: >> > >>>>>> >> > >>>>>>> Problem: >> > >>>>>>> We currently don't have a good user experience around "aurora job >> > >>>>>>> diff" command. The task configs are dumped as "prettified" JSON >> > >>>>>>> strings and diffed with the system diff tool. Anyone who tried to >> > >>> use >> > >>>>>>> it knows it can be very hard to read especially when it comes to >> > >>>>>>> executor data deltas. Also, the implementation is done completely >> > >>>>>>> within the Aurora client making it hard to reuse this feature by >> > >>> other >> > >>>>>>> clients (e.g.: an external deploy coordination tool). >> > >>>>>>> >> > >>>>>>> Proposal: >> > >>>>>>> Move the diff logic to the scheduler and expose it via a new >> > >>>>>>> jobConfigDiff thrift API. >> > >>>>>>> >> > >>>>>>> Benefits: >> > >>>>>>> - Client will no longer have the custom non-reusable logic moving >> > us >> > >>>>>>> closer towards a "thin client" goal. >> > >>>>>>> - The new RPC can be fully used by any existing or new API >> clients. >> > >>>>>>> - The diff output will be improved via leveraging third party >> POJO >> > >>>>>>> and/or JSON diff libraries [1,2,3, etc.]. >> > >>>>>>> - The server updater can be partially/fully unified with the new >> > >>> diff >> > >>>>>>> logic further improving the overall DRY-ness. >> > >>>>>>> >> > >>>>>>> Concerns: >> > >>>>>>> - The executor data is currently treated as an opaque string blob >> > on >> > >>>>>>> the scheduler side. In reality, it's almost guaranteed to be >> JSON. >> > >>> In >> > >>>>>>> order to deliver the best UX, the scheduler would have to start >> > >>>>>>> requiring ExecutorConfig.data to be a valid JSON. >> > >>>>>>> >> > >>>>>>> Any other concerns/objections/comments? I would like to formalize >> > >>> the >> > >>>>>>> proposal be EOW if we reach consensus quickly. >> > >>>>>>> >> > >>>>>>> Thanks, >> > >>>>>>> Maxim >> > >>>>>>> >> > >>>>>>> [1] - >> > >>> >> > >> http://java-object-diff.readthedocs.org/en/latest/getting-started/#getting-started >> > >>>>>>> [2] - http://javers.org/documentation/diff-examples/ >> > >>>>>>> [3] - https://github.com/skyscreamer/JSONassert >> > >>> >> > >>> -- >> > >>> Zameer Manji >> > >>> >> > >>> >> > >>
