Re: [DISCUSS] SqlClient gateway mode: support for URLs

[Alexander Fedulov <al...@gmail.com>]

One more requirement surfaced in the scope of introducing the above
mentioned improvements -  the need for SQL Gateway requests to be
authenticated. I propose to introduce an environmental variable,
FLINK_REST_CLIENT_HEADERS that could contain a list of HTTPS headers (
including authentication cookies) to be passed along with each RestClient
request.

Any objections or alternative suggestions?

Best,
Alex

On Mon, 8 May 2023 at 20:14, Alexander Fedulov <al...@gmail.com>
wrote:

> Hi Thomas,
>
> Thanks for the feedback. I created two separate tickets to track the
> related work:
> https://issues.apache.org/jira/browse/FLINK-32030
> https://issues.apache.org/jira/browse/FLINK-32035
>
> Best,
> Alex Fedulov
>
> On Wed, 3 May 2023 at 20:25, Thomas Weise <th...@apache.org> wrote:
>
>> Hi Alex,
>>
>> Thanks for the investigation and for the ideas on how to improve the SQL
>> gateway REST client.
>>
>> I think the solution could come in 2 parts. Near term the existing client
>> can be patched to support URL mapping and HTTPS based on a standard URL.
>> If
>> I understand your proposal correctly, that can be implemented in a
>> backward
>> compatible manner and w/o introducing additional dependencies.
>>
>> Long term it would make sense to switch to a specialized REST client, or
>> at
>> least the HTTP client that comes with Java 11 (after Flink says bye to JDK
>> 8 support).
>>
>> Do you have a JIRA for this work?
>>
>> Thanks,
>> Thomas
>>
>>
>> On Wed, May 3, 2023 at 11:46 AM Alexander Fedulov <
>> alexander.fedulov@gmail.com> wrote:
>>
>> > CC'ing some people who worked on the original implementation - curious
>> to
>> > hear your thoughts.
>> >
>> > Alex
>> >
>> > On Fri, 28 Apr 2023 at 14:41, Alexander Fedulov <
>> > alexander.fedulov@gmail.com>
>> > wrote:
>> >
>> > > I would like to discuss the current implementation of the SQL Gateway
>> > > support in SQL Cli Client and how it can be improved.
>> > >
>> > > 1) *hosname:port/v1 vs
>> > > https://hostname:port/flink-clusters/session-cluster-1/v1 *
>> > > Currently, the *--endpoint* parameter needs to be specified in the
>> > > *InetSocketAddress*  format, i.e. *hostname:port.* While this works
>> fine
>> > > for basic use cases, it does not support the placement of the gateway
>> > > behind a proxy or using an Ingress for routing to a specific Flink
>> > cluster
>> > > based on the URL path.  I.e. it expects *some.hostname.com:9001
>> > > <http://some.hostname.com:9001>*  to directly serve requests on *
>> > some.hostname.com:9001/v1
>> > > <http://some.hostname.com:9001/v1>* . Mapping to a non-root location,
>> > > i.e. *some.hostname.com:9001/flink-clusters/sql-preview-cluster-1/v1
>> > > <
>> http://some.hostname.com:9001/flink-clusters/sql-preview-cluster-1/v1>*
>> > >  is not supported. Since the client talks to the gateway via its REST
>> > > endpoint, I believe that the right format for the *--endpoint*
>> parameter
>> > > is *URL*, not *InetSocketAddress* .
>> > >
>> > > 2) *HTTPS support*
>> > > Another related issue is that internally SQL Client uses  Flink’s
>> > > *RestClient* [1].  This client decides whether to enable SSL not on
>> the
>> > > basis of the URL schema (https://...), but based on Flink
>> configuration,
>> > > namely a global *security.ssl.rest.enabled*  parameter [2] (which is
>> also
>> > > used for the REST server-side configuration ). When this parameter is
>> set
>> > > to true, it automatically requires user-supplied
>> > > *security.ssl.rest.truststore*  and *security.ssl.rest.keystore* to be
>> > > configured - there is no default option to use certificates from JDK.
>> I
>> > was
>> > > wondering if there is any real benefit in handling the low-level Netty
>> > > channels and certificates manually for the use case of connecting
>> between
>> > >  SQL Cli Client and SQL Gateway REST API.  There is already a
>> dependency
>> > on
>> > > *OkHttpClient*  in *flink-metrics*. I would like to hear what you
>> think
>> > > about switching to *OkHttp* and adding the ability to optionally load
>> > > custom certificates there rather than patching *RestClient*.
>> > >
>> > > [1]
>> > >
>> >
>> https://github.com/apache/flink/blob/5dddc0dba2be20806e67769314eecadf56b87a53/flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/gateway/ExecutorImpl.java#L359
>> > > [2]
>> > >
>> >
>> https://github.com/apache/flink/blob/5d9e63a16f079399c6b51547284bb96db0326bdb/flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestClientConfiguration.java#L103
>> > >
>> > > Best,
>> > > Alex Fedulov
>> > >
>> >
>>
>