Re: Bootstrapping Beam's Job Server
Thanks Henning and Thomas. It looks like
a) we want to keep the Docker Job Server Docker container and rely on
spinning up "sibling" SDK harness containers via the Docker socket. This
should require little changes to the Runner code.
b) have the InProcess SDK harness as an alternative way to running user
code. This can be done independently of a).
Thomas, let's sync today on the InProcess SDK harness. I've created a
JIRA issue: https://issues.apache.org/jira/browse/BEAM-5187
On 21.08.18 00:35, Thomas Weise wrote:
The original objective was to make test/development easier (which I
think is super important for user experience with portable runner).
From first hand experience I can confirm that dealing with Flink
clusters and Docker containers for local setup is a significant hurdle
for Python developers.
To simplify using Flink in embedded mode, the (direct) process based SDK
harness would be a good option, especially when it can be linked to the
same virtualenv that developers have already setup, eliminating extra
Max, I would be interested to sync up on what your thoughts are
regarding that option since you mention you also started to work on it
(see previous discussion , not sure if there is a JIRA for it yet).
Internally we are planning to use a direct SDK harness process instead
of Docker containers. For our specific needs it will works equally well
for development and production, including future plans to deploy Flink
TMs via Kubernetes.
On Mon, Aug 20, 2018 at 3:00 PM Maximilian Michels <mxm@xxxxxxxxxx
Thanks for your suggestions. Please see below.
> Option 3) would be to map in the docker binary and socket to allow
> the containerized Flink job server to start "sibling" containers on
> the host.
Do you mean packaging Docker inside the Job Server container and
mounting /var/run/docker.sock from the host inside the container? That
looks like a bit of a hack but for testing it could be fine.
> notably, if the runner supports auto-scaling or similar non-trivial
> configurations, that would be difficult to manage from the SDK side.
You're right, it would be unfortunate if the SDK would have to deal with
spinning up SDK harness/backend containers. For non-trivial
configurations it would probably require an extended protocol.
> Option 4) We are also thinking about adding process based SDKHarness.
> This will avoid docker in docker scenario.
Actually, I had started implementing a process-based SDK harness but
figured it might be impractical because it doubles the execution path
for UDF code and potentially doesn't work with custom dependencies.
> Process based SDKHarness also has other applications and might be
> desirable in some of the production use cases.
True. Some users might want something more lightweight.