In the end DYNAMIC_PROPERTIES behaves exactly like env.java.opts;
meaning that the existing rules set by the JVM apply.
Here's an example: export DYNAMIC_PROPERTIES='-Drest.port=1234
-Dother.option="iContainAn=Sign"'
This would then be appended as is to the /java/ command.
(
Conceptually at least; shells are annoying when it comes to
quotes/whitespace; good old http://mywiki.wooledge.org/BashFAQ/050.
Something like java ... $(eval echo ${DYNAMIC_PROPERTIES} handles
quotes nicely, but no spaces in values.
We should really move more logic from the scripts into the
BashJavaUtils...
)
On 1/26/2021 11:17 PM, Khachatryan Roman 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 .
I think we don't have to translate CUSTOM_MY_BACKEND_OPTION back. Instead,
we should use the key from the ConfigOption.
I'm assuming that not every ENV VAR will end up in the Configuration -
only those for which a matching ConfigOptions is found.
I'm also fine with a single ENV VAR (DYNAMIC_PROPERTIES). It's already a
big improvement.
In the future, we can consider adding smth like ConfigOption.withEnvVar for
some (most popular) options.
However, escaping is still not clear to me: how would kv-pairs be
separated? What if such a separator is in the value itself? What if '=' is
in the value?
Or am I missing something?
Regards,
Roman
On Tue, Jan 26, 2021 at 6:41 PM Till Rohrmann <trohrm...@apache.org> wrote:
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
