Hi Robert,

This seems like a reasonable behavior to me.  However, adding this behavior to 
FileConfigProvider seems like it might give someone who accidentally configures 
a directory rather than a file a nasty surprise.  How about adding a 
DirectoryConfigProvider which adds this behavior?

best,
Colin


On Tue, Sep 4, 2018, at 14:00, Robert Yokota wrote:
> Hi everyone,
> 
> Currently the FileConfigProvider, when passed a path that represents a
> Properties file, will read the file as a set of key-value pairs.
> 
> I've filed https://issues.apache.org/jira/browse/KAFKA-7370, which proposes
> to augment FileConfigProvider so that when a path representing a directory
> is passed, it will treat the file names as keys and the corresponding file
> contents as values.   This will allow for easier integration with secret
> management systems where each secret is often an individual file (such as
> when using Docker or Kubernetes).    The previous behavior is still
> retained, so this change is backward compatible.
> 
> Two questions:
> 
> 1) Does this seem like a reasonable idea?
> 
> 2) If it is a reasonable idea, is it ok to amend the KIP?
> 
> Thanks,
> Robert
> 
> On Mon, Jun 11, 2018 at 8:16 PM, Konstantine Karantasis <
> konstant...@confluent.io> wrote:
> 
> > Sounds great, happy to hear we all agree!
> > Thanks everyone!
> >
> >
> > - Konstantine
> >
> >
> > On Mon, Jun 11, 2018 at 4:22 PM, Colin McCabe <cmcc...@apache.org> wrote:
> >
> > > Sounds good.  Thanks, Konstantin.
> > >
> > > Colin
> > >
> > >
> > > On Mon, Jun 11, 2018, at 13:41, Rajini Sivaram wrote:
> > > > Hi Konstantine,
> > > >
> > > > Sounds reasonable to me too.
> > > >
> > > > Regards,
> > > >
> > > > Rajini
> > > >
> > > > On Mon, Jun 11, 2018 at 7:55 PM, Robert Yokota <rayok...@gmail.com>
> > > wrote:
> > > >
> > > > > Hi Konstantine,
> > > > >
> > > > > Sounds reasonable!
> > > > >
> > > > > Thanks,
> > > > > Robert
> > > > >
> > > > > On Mon, Jun 11, 2018 at 11:49 AM, Konstantine Karantasis <
> > > > > konstant...@confluent.io> wrote:
> > > > >
> > > > > > Hi everyone, after fixing an issue with a regular expression in
> > > Connect's
> > > > > > class loading isolation of the new component type ConfigProvider
> > > here:
> > > > > >
> > > > > > https://github.com/apache/kafka/pull/5177
> > > > > >
> > > > > > I noticed that the new interface ConfigProvider, along with its
> > first
> > > > > > implementation FileConfigProvider, have been placed in the package:
> > > > > >
> > > > > > org.apache.kafka.common.config
> > > > > >
> > > > > > This specific package is mentioned in KIP-297 is a few places, but
> > > not in
> > > > > > any code snippets. I'd like to suggest moving the interface and any
> > > > > current
> > > > > > of future implementation classes in a new package named:
> > > > > >
> > > > > > org.apache.kafka.common.config.provider
> > > > > >
> > > > > > and update the KIP document accordingly.
> > > > > >
> > > > > > This seems to make sense in general. But, specifically, in Connect
> > > it is
> > > > > > desired since we treat ConfigProvider implementations as Connect
> > > > > components
> > > > > > that are loaded in isolation. Having a package for config providers
> > > will
> > > > > > allow us to avoid making any assumptions with respect to the name
> > of
> > > a
> > > > > > class that implements `ConfigProvider` and is included in Apache
> > > Kafka.
> > > > > It
> > > > > > will suffice for this class to reside in the package
> > > > > > org.apache.kafka.common.config.provider.
> > > > > >
> > > > > > Let me know if this is a reasonable request and if you agree on
> > > amending
> > > > > > the KIP description.
> > > > > >
> > > > > > - Konstantine
> > > > > >
> > > > > >
> > > > > >
> > > > > > On Wed, May 16, 2018 at 10:33 AM, Rajini Sivaram <
> > > > > rajinisiva...@gmail.com>
> > > > > > wrote:
> > > > > >
> > > > > > > Thanks for the update, Robert. Looks good to me.
> > > > > > >
> > > > > > > Regards,
> > > > > > >
> > > > > > > Rajini
> > > > > > >
> > > > > > > On Wed, May 16, 2018 at 4:43 PM, Robert Yokota <
> > rayok...@gmail.com
> > > >
> > > > > > wrote:
> > > > > > >
> > > > > > > > Hi Rajini,
> > > > > > > >
> > > > > > > > Thanks for the excellent feedback!
> > > > > > > >
> > > > > > > > I've made the API changes that you've requested in the KIP.
> > > > > > > >
> > > > > > > >
> > > > > > > > > 1. Are we expecting one provider instance with different
> > > contexts
> > > > > > > > > provided to `ConfigProvider.get()`? If we created a different
> > > > > > provider
> > > > > > > > > instance for each context, we could deal with scheduling
> > > reloads in
> > > > > > the
> > > > > > > > > provider implementation?
> > > > > > > >
> > > > > > > > Yes, there would be one provider instance.  I've collapsed the
> > > > > > > > ConfigContext and the ConfigChangeCallback by adding a
> > parameter
> > > > > > delayMs
> > > > > > > to
> > > > > > > > indicate when the change will happen.  When a particular
> > > > > ConfigProvider
> > > > > > > > retrieves a lease duration along with a key, it can either 1)
> > > > > > schedule a
> > > > > > > > background thread to push out the change when it happens (at
> > > which
> > > > > time
> > > > > > > the
> > > > > > > > delayMs will be 0), or invoke the callback immediately with the
> > > lease
> > > > > > > > duration set as delayMs (of course, in this case the values for
> > > the
> > > > > > keys
> > > > > > > > will be the old values).  A ConfProvider could be parameterized
> > > to do
> > > > > > one
> > > > > > > > or the other.
> > > > > > > >
> > > > > > > >
> > > > > > > > > 2. Couldn't ConfigData  be an interface that just returns a
> > > map of
> > > > > > > > > key-value pairs. Providers that return metadata could extend
> > > it to
> > > > > > > > provide
> > > > > > > > > metadata in a meaningful format instead of Map<String,
> > String>.
> > > > > > > >
> > > > > > > > I've replaced ConfigData with Map<String, String> as you
> > > suggested.
> > > > > > > >
> > > > > > > >
> > > > > > > > > 3. For ZK, we would use ConfigProvider.get() without `keys`
> > to
> > > get
> > > > > > all
> > > > > > > > > keys in the path. Do we have two get() methods since some
> > > providers
> > > > > > > need
> > > > > > > > > keys to be specified and some don't? How do we decide which
> > > one to
> > > > > > use?
> > > > > > > >
> > > > > > > > The ConfigProvider should be thought of like a Map interface
> > and
> > > does
> > > > > > not
> > > > > > > > require that one signature of get() be preferred over the
> > other.
> > > > > > KIP-226
> > > > > > > > can use get(String path) while Connect will use get(String
> > path,
> > > > > > > > Set<String>) since it knows which keys it is interested in.
> > > > > > > >
> > > > > > > >
> > > > > > > > A few more updates to the KIP:
> > > > > > > >
> > > > > > > > - I've elided the ConfigTransformer implementation as Colin
> > > > > suggested.
> > > > > > > > - The variable reference now looks like ${provider:[path:]key}
> > > where
> > > > > > the
> > > > > > > > path is optional.
> > > > > > > >
> > > > > > > >
> > > > > > > > Thanks!
> > > > > > > > Robert
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > On Wed, May 16, 2018 at 4:30 AM, Rajini Sivaram <
> > > > > > rajinisiva...@gmail.com
> > > > > > > >
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > Hi Robert,
> > > > > > > > >
> > > > > > > > > Thanks for the KIP updates.
> > > > > > > > >
> > > > > > > > > The interfaces look suitable for brokers, with some small
> > > changes.
> > > > > If
> > > > > > > we
> > > > > > > > > can adapt the interface to implement the existing
> > > > > > DynamicBrokerConfig,
> > > > > > > > then
> > > > > > > > > we are good.
> > > > > > > > >
> > > > > > > > > With broker configs:
> > > > > > > > >
> > > > > > > > >    1. We don't know what configs are in ZK since we allow
> > > custom
> > > > > > > configs.
> > > > > > > > >    So we would use `ConfigProvider.get()` without specifying
> > > keys.
> > > > > > > > >    2. We want to see all changes (i.e. changes under a path).
> > > We
> > > > > can
> > > > > > > deal
> > > > > > > > >    with this internally by ignoring `keys` and subscribing to
> > > > > > > everything
> > > > > > > > >    3. We have two paths (one for per-broker config and
> > another
> > > for
> > > > > > > > default
> > > > > > > > >    config shared by all brokers). All methods should ideally
> > > > > provide
> > > > > > > > path -
> > > > > > > > >    see changes suggested below.
> > > > > > > > >    4. Keys are not independent. We update in batches (e.g
> > > keystore
> > > > > +
> > > > > > > > >    password). We want to see batches of changes, not
> > individual
> > > > > > > changes.
> > > > > > > > We
> > > > > > > > >    retrieve all values from a path when a change is detected.
> > > We
> > > > > can
> > > > > > do
> > > > > > > > > this
> > > > > > > > >    by ignoring values from the callback, but it would be
> > > better if
> > > > > > the
> > > > > > > > >    callback interface could be changed - see below.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > public interface ConfigProvider extends Configurable,
> > > Closeable {
> > > > > > > > >
> > > > > > > > >     *//** KIP-226 will use this*
> > > > > > > > >     ConfigData get(ConfigContext ctx, String path);
> > > > > > > > >
> > > > > > > > >     *// **KIP-226 will never use this, we don't know what
> > keys
> > > are
> > > > > in
> > > > > > > ZK
> > > > > > > > > since we allow custom configs*
> > > > > > > > >     ConfigData get(ConfigContext ctx, String path,
> > Set<String>
> > > > > keys);
> > > > > > > > >
> > > > > > > > > *    // KIP-226 will ignore `key` and subscribe to all
> > > changes.*
> > > > > > > > > *    // But based on the above method, this should perhaps
> > be:*
> > > > > > > > > *    //  subscribe(String path, Set<String> keys,
> > > > > > > > > ConfigurationChangeCallback callback)?*
> > > > > > > > >     void subscribe(String key, ConfigurationChangeCallback
> > > > > callback);
> > > > > > > > >
> > > > > > > > >      *<== As above, un**subscribe(String path, Set<String>
> > > > > keys)**?*
> > > > > > > > >     void unsubscribe(String key);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > public interface ConfigurationChangeCallback {
> > > > > > > > >     *// **For brokers, we want to process all updated keys
> > in a
> > > > > > single
> > > > > > > > > callback. P**erhaps this could be: *
> > > > > > > > >
> > > > > > > > > *    //   onChange(String path, Map<String, String> values)?*
> > > > > > > > >
> > > > > > > > >     void onChange(String key, String value);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > A few other questions (I read your response to Colin, but
> > still
> > > > > > didn't
> > > > > > > > get
> > > > > > > > > it. Could be because I am not familiar with the interfaces
> > > required
> > > > > > for
> > > > > > > > > vaults, sorry):
> > > > > > > > >
> > > > > > > > >    1. Are we expecting one provider instance with different
> > > > > contexts
> > > > > > > > >    provided to `ConfigProvider.get()`? If we created a
> > > different
> > > > > > > provider
> > > > > > > > >    instance for each context, we could deal with scheduling
> > > reloads
> > > > > > in
> > > > > > > > the
> > > > > > > > >    provider implementation?
> > > > > > > > >    2. Couldn't ConfigData  be an interface that just returns
> > a
> > > map
> > > > > of
> > > > > > > > >    key-value pairs. Providers that return metadata could
> > > extend it
> > > > > to
> > > > > > > > > provide
> > > > > > > > >    metadata in a meaningful format instead of Map<String,
> > > String>.
> > > > > > > > >    3. For ZK, we would use ConfigProvider.get() without
> > `keys`
> > > to
> > > > > get
> > > > > > > all
> > > > > > > > >    keys in the path. Do we have two get() methods since some
> > > > > > providers
> > > > > > > > need
> > > > > > > > >    keys to be specified and some don't? How do we decide
> > which
> > > one
> > > > > to
> > > > > > > > use?
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > >
> > > > > > > > > Rajini
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > On Wed, May 16, 2018 at 2:40 AM, Robert Yokota <
> > > rayok...@gmail.com
> > > > > >
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > > Thanks, Ron!  I will take a look.
> > > > > > > > > >
> > > > > > > > > > Regards,
> > > > > > > > > > Robert
> > > > > > > > > >
> > > > > > > > > > On Tue, May 15, 2018 at 5:59 PM, Ron Dagostino <
> > > > > rndg...@gmail.com>
> > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > > Hi Robert.  Regarding your comment "use the lease
> > duration
> > > to
> > > > > > > > schedule
> > > > > > > > > a
> > > > > > > > > > > configuration reload in the future", you might be
> > > interested in
> > > > > > the
> > > > > > > > > code
> > > > > > > > > > > that does refresh for OAuth Bearer Tokens in KIP-255;
> > > > > > specifically,
> > > > > > > > the
> > > > > > > > > > > class
> > > > > > > > > > > org.apache.kafka.common.security.oauthbearer.internal.
> > > > > expiring.
> > > > > > > > > > > ExpiringCredentialRefreshingLogin.
> > > > > > > > > > > The class performs JAAS logins/relogins based on the
> > > expiration
> > > > > > > time
> > > > > > > > > of a
> > > > > > > > > > > retrieved expiring credential.  The implementation of
> > that
> > > > > class
> > > > > > is
> > > > > > > > > > > inspired by the code that currently does refresh for
> > > Kerberos
> > > > > > > tickets
> > > > > > > > > but
> > > > > > > > > > > is more reusable.  I don't know if you will leverage JAAS
> > > for
> > > > > > > > defining
> > > > > > > > > > how
> > > > > > > > > > > to go get a credential (you could since you have to
> > provide
> > > > > > > > credentials
> > > > > > > > > > to
> > > > > > > > > > > authenticate to the remote systems anyway), but
> > regardless,
> > > > > that
> > > > > > > > class
> > > > > > > > > > > should be useful at least in some minimal sense if not
> > more
> > > > > than
> > > > > > > > that.
> > > > > > > > > > See
> > > > > > > > > > > https://github.com/apache/kafka/pull/4994.
> > > > > > > > > > >
> > > > > > > > > > > Ron
> > > > > > > > > > >
> > > > > > > > > > > Ron
> > > > > > > > > > >
> > > > > > > > > > > On Tue, May 15, 2018 at 8:01 PM, Robert Yokota <
> > > > > > rayok...@gmail.com
> > > > > > > >
> > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Hi Colin,
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks for the feedback!
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > The KIP says that "Vault is very popular and has been
> > > > > > described
> > > > > > > > as
> > > > > > > > > > 'the
> > > > > > > > > > > > current gold standard in secret management and
> > > > > > provisioning'."  I
> > > > > > > > > think
> > > > > > > > > > > > this might be a bit too much detail -- we don't really
> > > need
> > > > > to
> > > > > > > > > > > > > favorites, right? :)
> > > > > > > > > > > >
> > > > > > > > > > > > I've removed this line :)
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > I think we should make the substitution part of the
> > > generic
> > > > > > > > > > > configuration
> > > > > > > > > > > > code, rather than specific to individual
> > > ConfigProviders.  We
> > > > > > > don't
> > > > > > > > > > > really
> > > > > > > > > > > > want it to work differently for Vault vs. KeyWhiz vs.
> > > > > > > > > > > > > AWS secrets, etc. etc.
> > > > > > > > > > > >
> > > > > > > > > > > > Yes, the ConfigProviders merely serve up key-value
> > > pairs.  A
> > > > > > > helper
> > > > > > > > > > class
> > > > > > > > > > > > like ConfigTransformer would perform the variable
> > > > > substitutions
> > > > > > > if
> > > > > > > > > > > desired.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > We should also spell out exactly how substitution
> > > works.
> > > > > > > > > > > >
> > > > > > > > > > > > By one-level of indirection I just meant a simple
> > > replacement
> > > > > > of
> > > > > > > > > > > variables
> > > > > > > > > > > > (which are the indirect references).  So if you have
> > > > > foo=${bar}
> > > > > > > and
> > > > > > > > > > > > bar=${baz} and your file contains bar=hello, baz=world,
> > > then
> > > > > > the
> > > > > > > > > final
> > > > > > > > > > > > result would be foo=hello and bar=world.  I've added
> > this
> > > > > > example
> > > > > > > > to
> > > > > > > > > > the
> > > > > > > > > > > > KIP.
> > > > > > > > > > > >
> > > > > > > > > > > > You can see this as the DEFAULT_PATTERN in the
> > > > > > ConfigTransformer.
> > > > > > > > > The
> > > > > > > > > > > > ConfigTransformer only provides one level of
> > indirection.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > We should also spell out how this interacts with
> > > KIP-226
> > > > > > > > > > > configurations.
> > > > > > > > > > > >
> > > > > > > > > > > > Yes, I mention at the beginning that KIP-226 could use
> > > the
> > > > > > > > > > ConfigProvider
> > > > > > > > > > > > but not the ConfigTransformer.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > Maybe a good generic interface would be like this:
> > > > > > > > > > > >
> > > > > > > > > > > > I've added the subscription APIs but would like to keep
> > > the
> > > > > > other
> > > > > > > > > APIs
> > > > > > > > > > > as I
> > > > > > > > > > > > will need them for integration with Vault.  With Vault
> > I
> > > > > obtain
> > > > > > > the
> > > > > > > > > > lease
> > > > > > > > > > > > duration at the time the key is obtained, so at that
> > > time I
> > > > > > would
> > > > > > > > > want
> > > > > > > > > > to
> > > > > > > > > > > > use the lease duration to schedule a configuration
> > > reload in
> > > > > > the
> > > > > > > > > > future.
> > > > > > > > > > > > This is similar to how the integration between Vault
> > and
> > > the
> > > > > > > Spring
> > > > > > > > > > > > Framework works.   Also, the lease duration would be
> > > included
> > > > > > in
> > > > > > > > the
> > > > > > > > > > > > metadata map vs. the data map.  Finally, I need an
> > > additional
> > > > > > > > "path"
> > > > > > > > > or
> > > > > > > > > > > > "bucket" parameter, which is used by Vault to indicate
> > > which
> > > > > > set
> > > > > > > of
> > > > > > > > > > > > key-values are to be retrieved.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > With regard to ConfigTransformer: do we need to
> > > include all
> > > > > > > this
> > > > > > > > > code
> > > > > > > > > > > in
> > > > > > > > > > > > the KIP?  Seems like an implementation detail.
> > > > > > > > > > > >
> > > > > > > > > > > > I use the ConfigTransformer to show how the pattern
> > > > > > > ${provider:key}
> > > > > > > > > is
> > > > > > > > > > > > defined and how the substitution only involves one
> > level
> > > of
> > > > > > > > > > indirection.
> > > > > > > > > > > > If you feel it does not add anything to the text, I can
> > > > > remove
> > > > > > > it.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > Is there a way to avoid this couping?
> > > > > > > > > > > >
> > > > > > > > > > > > I'd have to look into it and get back to you.
> > However, I
> > > > > > assume
> > > > > > > > that
> > > > > > > > > > the
> > > > > > > > > > > > answer is not relevant for this KIP :)
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks,
> > > > > > > > > > > > Robert
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > On Tue, May 15, 2018 at 4:04 PM, Colin McCabe <
> > > > > > > cmcc...@apache.org>
> > > > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > > Hi Robert,
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks for posting this.  In the past we've been kind
> > > of
> > > > > > > > reluctant
> > > > > > > > > to
> > > > > > > > > > > add
> > > > > > > > > > > > > more complexity to configuration.  I think Connect
> > does
> > > > > have
> > > > > > a
> > > > > > > > > clear
> > > > > > > > > > > need
> > > > > > > > > > > > > for this kind of functionality, though.  As you
> > > mention,
> > > > > > > Connect
> > > > > > > > > > > > integrates
> > > > > > > > > > > > > with external systems, which are very likely to have
> > > > > > passwords
> > > > > > > > > stored
> > > > > > > > > > > in
> > > > > > > > > > > > > Vault, KeyWhiz or some other external system.
> > > > > > > > > > > > >
> > > > > > > > > > > > > The KIP says that "Vault is very popular and has been
> > > > > > described
> > > > > > > > as
> > > > > > > > > > 'the
> > > > > > > > > > > > > current gold standard in secret management and
> > > > > > > provisioning'."  I
> > > > > > > > > > think
> > > > > > > > > > > > > this might be a bit too much detail -- we don't
> > really
> > > need
> > > > > > to
> > > > > > > > pick
> > > > > > > > > > > > > favorites, right? :)
> > > > > > > > > > > > >
> > > > > > > > > > > > > I think we should make configuration consistent
> > > between the
> > > > > > > > broker
> > > > > > > > > > and
> > > > > > > > > > > > > Connect.  If people can use constructs like
> > > > > > > > > > > > jdbc.config.key="${vault:jdbc.
> > > user}${vault:jdbc.password}"
> > > > > > > > > > > > > in Connect, they'll want to do it on the broker too,
> > > in a
> > > > > > > > > consistent
> > > > > > > > > > > way.
> > > > > > > > > > > > >
> > > > > > > > > > > > > If I understand correctly, ConfigProvider represents
> > an
> > > > > > > external
> > > > > > > > > > > > > configuration source, such as VaultConfigProvider,
> > > > > > > > > > > KeyWhizConfigProvider,
> > > > > > > > > > > > > etc.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I think we should make the substitution part of the
> > > generic
> > > > > > > > > > > configuration
> > > > > > > > > > > > > code, rather than specific to individual
> > > ConfigProviders.
> > > > > We
> > > > > > > > don't
> > > > > > > > > > > > really
> > > > > > > > > > > > > want it to work differently for Vault vs. KeyWhiz vs.
> > > AWS
> > > > > > > > secrets,
> > > > > > > > > > etc.
> > > > > > > > > > > > etc.
> > > > > > > > > > > > >
> > > > > > > > > > > > > We should also spell out exactly how substitution
> > > works.
> > > > > For
> > > > > > > > > > example,
> > > > > > > > > > > is
> > > > > > > > > > > > > substitution limited to 1 level deep?  In other
> > words,
> > > If I
> > > > > > > have
> > > > > > > > > > > > > foo="${bar}" and bar=${baz}, probably foo should just
> > > be
> > > > > set
> > > > > > > > equal
> > > > > > > > > to
> > > > > > > > > > > > > "${baz}" rather than chasing more than one level of
> > > > > > > indirection.
> > > > > > > > > > > > >
> > > > > > > > > > > > > We should also spell out how this interacts with
> > > KIP-226
> > > > > > > > > > > configurations.
> > > > > > > > > > > > > I would suggest that KIP-226 variables not be
> > > subjected to
> > > > > > > > > > > substitution.
> > > > > > > > > > > > > The reason is because in theory substitution could
> > > lead to
> > > > > > > > > different
> > > > > > > > > > > > > results on different brokers, since the different
> > > brokers
> > > > > may
> > > > > > > not
> > > > > > > > > > have
> > > > > > > > > > > > the
> > > > > > > > > > > > > same ConfigProviders configured.  Also, having
> > > > > substitutions
> > > > > > in
> > > > > > > > the
> > > > > > > > > > > > KIP-226
> > > > > > > > > > > > > configuration makes it more difficult for the admin
> > to
> > > > > > > understand
> > > > > > > > > > what
> > > > > > > > > > > > the
> > > > > > > > > > > > > centrally managed configuration is.
> > > > > > > > > > > > >
> > > > > > > > > > > > > It seems the main goal is the ability to load a batch
> > > of
> > > > > > > > key/value
> > > > > > > > > > > pairs
> > > > > > > > > > > > > from the ConfigProvider, and the ability to subscribe
> > > to
> > > > > > > > > > notifications
> > > > > > > > > > > > > about changes to certain parameters.  Maybe a good
> > > generic
> > > > > > > > > interface
> > > > > > > > > > > > would
> > > > > > > > > > > > > be like this:
> > > > > > > > > > > > >
> > > > > > > > > > > > >  > public interface ConfigProvider extends Closeable
> > {
> > > > > > > > > > > > > >      // batched get is potentially more efficient
> > > > > > > > > > > > >  >     Map<String, String> get(Collection<String>
> > > keys);
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >    // The ConfigProvider is responsible for making
> > > this
> > > > > > > > callback
> > > > > > > > > > > > > whenever the key changes.
> > > > > > > > > > > > > >    // Some ConfigProviders may want to have a
> > > background
> > > > > > > thread
> > > > > > > > > > with
> > > > > > > > > > > a
> > > > > > > > > > > > > configurable update interval.
> > > > > > > > > > > > >  >     void subscribe(String key,
> > > > > ConfigurationChangeCallback
> > > > > > > > > > > callback);
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >        // Inverse of subscribe
> > > > > > > > > > > > >  >     void unsubscribe(String key);
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >    // Close all subscriptions and clean up all
> > > resources
> > > > > > > > > > > > >  >     void close();
> > > > > > > > > > > > >  > }
> > > > > > > > > > > > >  >
> > > > > > > > > > > > >  > interface ConfigurationChangeCallback {
> > > > > > > > > > > > >  >     void onChange(String key, String value);
> > > > > > > > > > > > >  > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > With regard to ConfigTransformer: do we need to
> > > include all
> > > > > > > this
> > > > > > > > > code
> > > > > > > > > > > in
> > > > > > > > > > > > > the KIP?  Seems like an implementation detail.
> > > > > > > > > > > > >
> > > > > > > > > > > > > > Other connectors such as the S3 connector are
> > tightly
> > > > > > coupled
> > > > > > > > > with
> > > > > > > > > > a
> > > > > > > > > > > > > particular secret manager, and may
> > > > > > > > > > > > > > wish to handle rotation on their own.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Is there a way to avoid this couping?  Seems like
> > some
> > > > > users
> > > > > > > > might
> > > > > > > > > > want
> > > > > > > > > > > > to
> > > > > > > > > > > > > use their own secret manager here.
> > > > > > > > > > > > >
> > > > > > > > > > > > > best,
> > > > > > > > > > > > > Colin
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Wed, May 9, 2018, at 16:32, Robert Yokota wrote:
> > > > > > > > > > > > > > Hi Magesh,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I updated the KIP with a link to a PR for a working
> > > > > > > prototype.
> > > > > > > > > The
> > > > > > > > > > > > > > prototype does not yet use the Connect plugin
> > > machinery
> > > > > for
> > > > > > > > class
> > > > > > > > > > > > loader
> > > > > > > > > > > > > > isolation, but should give you an idea of what the
> > > final
> > > > > > > > > > > implementation
> > > > > > > > > > > > > > will look like.  Here is the link:
> > > > > > > > > > > > > > https://github.com/apache/kafka/pull/4990/files.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I also added an example of a FileConfigProvider to
> > > the
> > > > > KIP.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > Robert
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Wed, May 9, 2018 at 10:04 AM, Robert Yokota <
> > > > > > > > > rayok...@gmail.com
> > > > > > > > > > >
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi Magesh,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks for the feedback!
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I will put together a PR to demonstrate what the
> > > > > > > > implementation
> > > > > > > > > > > might
> > > > > > > > > > > > > look
> > > > > > > > > > > > > > > like, as well as a reference FileConfigProvider.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 1.  The delayMs for a (potentially) scheduled
> > > reload is
> > > > > > > > > > determined
> > > > > > > > > > > by
> > > > > > > > > > > > > the
> > > > > > > > > > > > > > > ConfigProvider.  For example, a (hypothetical)
> > > > > > > > > > VaultConfigProvider,
> > > > > > > > > > > > > upon
> > > > > > > > > > > > > > > contacting Vault for a particular secret, might
> > > also
> > > > > > > obtain a
> > > > > > > > > > lease
> > > > > > > > > > > > > > > duration indicating that the secret expires in 1
> > > hour.
> > > > > > The
> > > > > > > > > > > > > > > VaultConfigProvider could then call
> > > > > scheduleConfigReload
> > > > > > > with
> > > > > > > > > > > delayMs
> > > > > > > > > > > > > set
> > > > > > > > > > > > > > > to 3600000ms (1 hour).  This would cause the
> > > Connector
> > > > > to
> > > > > > > > > restart
> > > > > > > > > > > in
> > > > > > > > > > > > an
> > > > > > > > > > > > > > > hour, forcing it to reload the configs and
> > > re-resolve
> > > > > all
> > > > > > > > > > indirect
> > > > > > > > > > > > > > > references.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 2. Yes, the start() methods in SourceTask and
> > > SinkTask
> > > > > > > would
> > > > > > > > > get
> > > > > > > > > > > the
> > > > > > > > > > > > > > > configs with all the indirect references
> > resolved.
> > > > > >  Those
> > > > > > > > > > config()
> > > > > > > > > > > > > methods
> > > > > > > > > > > > > > > are for Connectors that want to get the latest
> > > configs
> > > > > > > (with
> > > > > > > > > all
> > > > > > > > > > > > > indirect
> > > > > > > > > > > > > > > references re-resolved) at some time after
> > start().
> > > > > For
> > > > > > > > > example,
> > > > > > > > > > > if
> > > > > > > > > > > > a
> > > > > > > > > > > > > Task
> > > > > > > > > > > > > > > encountered some security exception because a
> > > secret
> > > > > > > expired,
> > > > > > > > > it
> > > > > > > > > > > > could
> > > > > > > > > > > > > call
> > > > > > > > > > > > > > > config() to get the config with the latest
> > values.
> > > > > This
> > > > > > is
> > > > > > > > > > > assuming
> > > > > > > > > > > > > that
> > > > > > > > > > > > > > > the Task can gracefully recover from the security
> > > > > > > exception.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 3. Yes, that is up to the ConfigProvider
> > > implementation
> > > > > > and
> > > > > > > > is
> > > > > > > > > > out
> > > > > > > > > > > of
> > > > > > > > > > > > > > > scope.  If the ConfigProvider also needs some
> > kind
> > > of
> > > > > > > secrets
> > > > > > > > > or
> > > > > > > > > > > > other
> > > > > > > > > > > > > > > data, it could possibly be passed in through the
> > > param
> > > > > > > > > properties
> > > > > > > > > > > > > > > ("config.providers.vault.
> > param.auth=/run/myauth").
> > > > > For
> > > > > > > > > example
> > > > > > > > > > > > Docker
> > > > > > > > > > > > > > > might generate the auth info for Vault in an
> > > in-memory
> > > > > > > tmpfs
> > > > > > > > > file
> > > > > > > > > > > > that
> > > > > > > > > > > > > > > could then be passed as a param.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > Robert
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Tue, May 8, 2018 at 10:10 PM, Magesh
> > Nandakumar
> > > <
> > > > > > > > > > > > > mage...@confluent.io>
> > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >> Hi Robert,
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> Thanks for the KIP. I think, this will be a
> > great
> > > > > > addition
> > > > > > > > to
> > > > > > > > > > the
> > > > > > > > > > > > > > >> framework. I think, will be great if the KIP can
> > > > > > > elaborate a
> > > > > > > > > > > little
> > > > > > > > > > > > > bit
> > > > > > > > > > > > > > >> more on how implementations would look like with
> > > an
> > > > > > > example.
> > > > > > > > > > > > > > >> Also, would be good to provide a reference
> > > > > > implementation
> > > > > > > as
> > > > > > > > > > well.
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> The other questions I had were
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> 1.  How would the framework get the delayMs for
> > > void
> > > > > > > > > > > > > scheduleConfigReload(
> > > > > > > > > > > > > > >> long delayMs);
> > > > > > > > > > > > > > >> 2. Would the start methods in SourceTask and
> > > SinkTask
> > > > > > get
> > > > > > > > the
> > > > > > > > > > > > configs
> > > > > > > > > > > > > with
> > > > > > > > > > > > > > >> all the indirect references resolved. If so,
> > > trying to
> > > > > > > > > > understand
> > > > > > > > > > > > > > >> the intent of the config() in SourceTaskContext
> > > and
> > > > > the
> > > > > > > > > > > > > SinkTaskContext
> > > > > > > > > > > > > > >> 3. What if the provider itself needs some kind
> > of
> > > > > > secrets
> > > > > > > to
> > > > > > > > > be
> > > > > > > > > > > > > configured
> > > > > > > > > > > > > > >> to connect to it? I assume that's out of scope
> > for
> > > > > this
> > > > > > > > > proposal
> > > > > > > > > > > but
> > > > > > > > > > > > > > >> wanted
> > > > > > > > > > > > > > >> to clarify it.
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> Thanks
> > > > > > > > > > > > > > >> Magesh
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> On Tue, May 8, 2018 at 1:52 PM, Robert Yokota <
> > > > > > > > > > rayok...@gmail.com
> > > > > > > > > > > >
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >> > Hi,
> > > > > > > > > > > > > > >> >
> > > > > > > > > > > > > > >> > I would like to start a discussion for KIP-297
> > > to
> > > > > > > > > externalize
> > > > > > > > > > > > > secrets
> > > > > > > > > > > > > > >> from
> > > > > > > > > > > > > > >> > Kafka Connect configurations.  Any feedback is
> > > > > > > > appreciated.
> > > > > > > > > > > > > > >> > <
> > > > > > > > > > > > > > >> > https://cwiki.apache.org/
> > > > > > confluence/display/KAFKA/KIP-
> > > > > > > > > > > > > > >> > 297%3A+Externalizing+Secrets+
> > > > > > for+Connect+Configurations
> > > > > > > > > > > > > > >> > >
> > > > > > > > > > > > > > >> >
> > > > > > > > > > > > > > >> > JIRA: <https://issues.apache.org/
> > > > > > jira/browse/KAFKA-6886
> > > > > > > >
> > > > > > > > > > > > > > >> >
> > > > > > > > > > > > > > >> > Thanks in advance,
> > > > > > > > > > > > > > >> > Robert
> > > > > > > > > > > > > > >> >
> > > > > > > > > > > > > > >>
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > >
> >

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