Github user aledsage commented on the pull request:
https://github.com/apache/incubator-brooklyn/pull/1030#issuecomment-156714424
Taking a step back from the minor comments I've been making so far... This
feels like a lot of code we have to write for the SimpleCommand entity. I
wonder if there is another way of doing it that does not involve copying the
pattern used in the `SoftwareProcess` entity.
The "driver pattern" was really introduced to have different
implementations depending on whether it was ssh or something else - and it's
never used for anything but ssh. The "LifecycleEffectorTasks pattern" is mostly
for ensuring that all the different parts of the entity deployment/actions are
executed correctly as tasks that are tracked in the activity view. It includes
support for many tasks being executed (e.g. for pre-install, install,
post-install, customize, etc). We don't need all that complexity for
`SimpleCommand`.
All we really need is to get hold of the right SshMachineLocation and to
execute a command on it using `sshMachine.execScript()`.
For the download-url case, we could download it on Brooklyn, and just pass
the string contents to `sshMachine.execScript`, or if it might be binary then
we could use `machine.copyTo(...); machine.execScript(...)`.
To ensure the command's stdout/stderr etc appears in the activites view
correctly, we can go through the `SshEffectorTasks` stuff rather than calling
methods on machine directly.
My gut feel is that we could put that code directly in the start() method
of the `SimpleCommandImpl` (or more accurately in a method that it delegates
to).
Does that sound like it would work, and does it sound like it would reduce
massively the amount of code required?
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