I think I got a handle on this. For those who might want to do this
Here are the steps ( I could share the Jetty/Jersey REST code too is
required )
*1.* Create a side car container on each pod that has a TM. I wrote a
simple Jetty/Jersey REST based server that execute queries against the
local TM query server.
.
.
- name: queryable-state
image: _IMAGE_
args: ["queryable-state"]
env:
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
ports:
- containerPort: 9999
name: qstate-client
resources:
requests:
cpu: "0.25"
memory: "256Mi"
Note that POD_IP is the ip used by the REST based server to start the
QueryableStateClient and the port is the default port of the TM query
server ( 9069 I think ) of the colocated TM container.
*2.* Expose the port ( in this case 9999 ) at the k8s service layer.
And that did it.
I though am worried about a couple of things
*1*.
The TM query server will ask JM for the key group and hence the TM a key
belongs to for every request and then coordinate the coummunication between
the client and that TM. Does flink do any optimzation, as in cache the key
ranges and thus the affinity to a TM to reduce JM stress. I would imagine
that being some well known distribution function on some well known hash
algorithm, an incident key could be pinned to a TM without visiting the JM
more then once.
*2. *
We do have use cases where we would want to iterate over all the keys in a
key group ( and by extension on a TM ) for a job. Is that a possibility ?
*3. *
The overhead of having as many client containers as TMs.
Any advise/ideas on the 3 worry points ?
Regards
On Mon, Mar 25, 2019 at 8:57 PM Vishal Santoshi <vishal.santo...@gmail.com>
wrote:
> I have 2 options
>
> 1. A Rest Based, in my case a Jetty/REST based QueryableStateClient in a
> side car container colocated on JM ( Though it could on all TMs but that
> looks to an overkill )
>
> 2.A Rest Based, in my case a Jetty/REST based QueryableStateClient in a
> side car container colocated on TMs. The Query Proxies are on the TMs, so
> in essence the communication would be within containers of the POD and I
> could load balance ( have ot test )
>
> The second alternative seems doable, but looks an overkill but am not
> sure how to establish a TM on the standalone QueryableStateClient, given
> that TM's pod IP is not known till the pod is launched.
>
> Has anyone had a successful QueryableState setup for flink on k8s?
>
> Regards,
>
