> On Apr 16, 2018, at 2:04 PM, Chun-Hung Hsiao <chhs...@apache.org> wrote:
>
> Hi all,
>
> As some might have already known, we are currently working on patches to
> implement the new GROW_VOLUME and SHRINK_VOLUME operations [1].
>
> One problem surfaces is that, since the new operations are not supported in
> Mesos 1.5, they will lead to an agent crash during the operation application
> cycle if a Mesos 1.6 master send these operations to a Mesos 1.5 agent [2].
>
> We are now consider two possibilities to address this compatibility problem:
>
> 1) The Mesos 1.6 master should check the agent's Mesos version in
> `Master::accept` [3]. Moving forward, if we add new operations in future
> Mesos
> releases, we would have code like the following:
Using a capability follows the existing practice. I'm also sympathetic to the
argument that this is an experimental feature and will cause 1.5 agents will
crash.
> 2) Treat this issue as an agent crash bug. The Mesos master would forward
> the operation to the agent, regardless of the agent's Mesos version. In the
> agent,
> we deploy and backport the following logic in `Slave::applyOperation` [4]:
>
> ```
> if (message.operation_info().type() == OPERATION_UNKNOWN) {
> ... // Drop the operation and trigger a re-registration or send an
> // `UpdateSlaveMessage` to force the master to update the total
> resource of
> // the slave.
> }
> ```
You should never drop operations. This should respond with some sort of
"UNKNOWN/UNSUPPORTED" status.
J
