Thinking a bit more about the DYNAMIC_PROPERTIES, I have to admit that I
like the fact that it works around the problem of encoding the key names
and that it is more powerful wrt to bulk changes. Also the fact that one
can copy past configuration snippets is quite useful. Given these aspects
and that we wouldn't exclude any mentioned configuration scenarios, I would
also be ok following this approach given that we support it for all Flink
processes.
Cheers,
Till
On Tue, Jan 26, 2021 at 5:10 PM Ingo Bürk <i...@ververica.com> wrote:
> Hi everyone,
>
> thanks for the livid discussion, it's great to see so many opinions and
> ideas!
>
> The point about underscores is a very valid point where the current FLIP,
> if we were to stick with it, would have to be improved. I was going to say
> that we should exclude that from the discussion about the merits of
> different overall solutions, but I am afraid that this makes the "how to
> name EVs" question even more convoluted, and that in turn directly impacts
> the usefulness of the FLIP as a whole which is about a more convenient way
> of configuring Flink; names which are too cryptic will not achieve that. So
> in this regard I am in agreement with Chesnay.
>
> After all these considerations, speaking from the Kubernetes context, it
> seems to me that using the dynamic properties works best (I can use config
> key names as-is) and requires no change, so I'm actually just leaning
> towards that. However, the Kubernetes context is, I guess, not the only one
> to consider.
>
>
> Best regards
> Ingo
>
> On Tue, Jan 26, 2021 at 3:48 PM Chesnay Schepler <ches...@apache.org>
> wrote:
>
> > Mind you that we could of course solve these character issues by first
> > nailing down which characters we allow in keys (presumably: [a-z0-9-.]).
> >
> > On 1/26/2021 3:45 PM, Chesnay Schepler wrote:
> > > Here's an example: My option key is custom.my_backend_option. With the
> > > current design, the corresponding env variable would be
> > > CUSTOM_MY_BACKEND_OPTION, which would be converted into
> > > custom.my.backend.option .
> > >
> > > It is true that users could still parse the original system property
> > > as a fall-back, but it seems to partially invalidate the goal and
> > > introduce the potential for surprises and inconsistent behavior.
> > >
> > > What would happen if the option were already defined in the
> > > flink-conf.yaml, but overwritten with the env variable? Users would
> > > have to check every time they access a configuration whether the
> > > system property was also set and resolve things manually. Naturally
> > > things might also conflict with whatever prioritization we come up
> with.
> > >
> > > Now you might say that this is only necessary if the option contains
> > > special characters, but then we're setting users up for a surprise
> > > should they ever rename an existing option to contain an underscore.
> > >
> > > As for newlines, I wouldn't expect newline characters to appear within
> > > DYNAMIC_VARIABLE, but I guess it would follow the same behavior as if
> > > you would declare them on the command-line?
> > >
> > > One more downside I see is that from a users perspective I'd always
> > > have to do this conversion manually. You can't just copy stuff from
> > > the documentation (unless we duplicate every single mention), nor can
> > > you easily switch between environment variables and dynamic
> > > properties/flink-conf.yaml . For the use-cases that people seems to be
> > > concerned about (where you have lots of variables) I would think that
> > > this is a deal-breaker.
> > >
> > > On 1/26/2021 2:59 PM, Khachatryan Roman wrote:
> > >> @Chesnay
> > >> could you explain how underscores in user-defined properties would be
> > >> affected with transformation like STATE_BACKEND -> state.backend?
> > >> IIUC, this transformation happens in Flink and doesn't alter ENV
> > >> vars, so
> > >> the user app can still parse the original configuration.
> > >> OTH, I'm a bit concerned whether the newline should be escaped by the
> > >> user
> > >> in DYNAMIC_VARIABLES.
> > >>
> > >> @Ingo Bürk <i...@ververica.com>
> > >> I feel a bit lost in the discussion) Maybe we can put an intermediate
> > >> summary of pros and cons of different approaches into the FLIP?
> > >>
> > >> And for completeness, we could combine DYNAMIC_VARIABLES approach with
> > >> passing individual variables.
> > >>
> > >>
> > >> Regards,
> > >> Roman
> > >>
> > >>
> > >> On Tue, Jan 26, 2021 at 12:54 PM Chesnay Schepler <ches...@apache.org
> >
> > >> wrote:
> > >>
> > >>> I think we have to assume that some user has a custom config option
> > >>> that
> > >>> uses underscores.
> > >>>
> > >>> That said, we can probably assume that no one uses other special
> > >>> characters like question marks and such, which are indeed allowed by
> > >>> the
> > >>> YAML spec.
> > >>>
> > >>> These kind of questions are precisely why I prefer the
> > >>> DYNAMIC_VARIABLES
> > >>> approach; you don't even have to worry about this stuff.
> > >>> The only question we'd have to answer is whether manually defined
> > >>> properties should take precedent or not.
> > >>>
> > >>> @Uce I can see how it could be cumbersome to modify, but at the same
> > >>> time you can implement whatever other approach you want on top of it:
> > >>>
> > >>> // this is a /conceptual /example for an optional setting
> > >>> DYNAMIC_VARIABLES="${REST_PORT_SETTING}"
> > >>> if _someCondition_:
> > >>> export REST_PORT_SETTING="-Drest.port=1234"
> > >>>
> > >>> // this is a /conceptual /example for a configurable setting
> > >>> DYNAMIC_VARIABLES="-Drest.port=${MY_FANCY_VARIABLE:-8200}"
> > >>> if _someCondition_:
> > >>> export MY_FANCY_VARIABLE="1234"
> > >>>
> > >>> Additionally, this makes it quite easy to audit stuff, since we can
> > >>> just
> > >>> eagerly log what DYNAMIC_VARIABLES is set to.
> > >>>
> > >>> On 1/26/2021 12:48 PM, Xintong Song wrote:
> > >>>> @Ufuk,
> > >>>> I also don't find any existing options with underscores in their
> keys.
> > >>>> However, I do not find any explicit rules forbid using them either.
> > >>>> I'm
> > >>> not
> > >>>> saying this should block the FLIP. Just it would be nice to beware
> of
> > >>> this
> > >>>> issue, and maybe ensure the assumption with test cases if we finally
> > >>> decide
> > >>>> to go with these mapping rules.
> > >>>>
> > >>>> Thank you~
> > >>>>
> > >>>> Xintong Song
> > >>>>
> > >>>>
> > >>>>
> > >>>> On Tue, Jan 26, 2021 at 7:27 PM Ufuk Celebi <u...@apache.org> wrote:
> > >>>>
> > >>>>> @Xingtong: The assumption for the mapping was that we only have
> > >>>>> dots and
> > >>>>> hyphens in the keys. Do you have an example for a key which include
> > >>>>> underscores? If underscores are common for keys (I couldn't find
> any
> > >>>>> existing options that use it), it would certainly be a blocker for
> > >>>>> the
> > >>>>> discussed approach.
> > >>>>>
> > >>>>> On Tue, Jan 26, 2021, at 11:46 AM, Xintong Song wrote:
> > >>>>>> - The naming conversions proposed in the FLIP seems not
> > >>>>>> bijective
> > >>> to
> > >>>>> me.
> > >>>>>> There could be problems if the configuration key contains
> > >>> underscores.
> > >>>>>> - a_b -> FLINK_CONFIG_a_b
> > >>>>>> - FLINK_CONFIG_a_b -> a.b
> > >>>
> > >>>
> > >
> >
> >
>
