Adding ignore_changes lifecycle flag

[robzienert]

First stab at adding an "ignore_updates" lifecycle flag; addresses #2437.

[joekhoobyar]

+1

[maxenglander]

+1!

[JeanMertz]

Yes! Just came looking for this after:

~ aws_eip.core
    instance: "i-92eeed5c" => ""

as I can't let Terraform manage this EIP.

[dalehamel]

👍

[dalehamel]

Unfortunately, doesn't seem to work:

* aws_route_table.subnet_routing_table.0: diffs didn't match during apply. This is a bug with Terraform and should be reported.

Maybe this is just an issue with resources with count?

[pmoust]

Hi @robzienert , please have a look at #2018 (comment) where a meta-paremeter is proposed to ignore changes in targeted attributes of a resource.

[robzienert]

@pmoust I like this a lot more. Not sure why I didn't see that issue when I was originally working on this PR. I'll work on getting this updated this coming weekend to use a list of properties, rather than being resource-level.

[berset]

Would love to see this feature! 👍

[robzienert]

Finally got around to updating the PR. Right now it ignores attributes by their name, not state ID, but I would like to support both however I'm running into an issue with my implementation. For example:

I have a dynamic route on an aws_route_table resource. When defining a state ID, like route.1157028409 in aws_route_table, the route.# value stays the same, saying that a route is still being removed. Makes me think I'm evaling the diff in the wrong place.

[phinze]

@robzienert This is looking good! If you could add a covering unit test or two in our higher level context tests, I think this should be merge-able. Let me know if the tests are any trouble and one of us can help pick them up.

[robzienert]

Welcome back @phinze. Will look into this - until then, do you have any feedback re my previous comment?

[phinze]

Oh right! Sorry about missing that, @robzienert

Right now it ignores attributes by their name, not state ID, but I would like to support both however I'm running into an issue with my implementation.

I'm not sure we should expose the internals of state storage as an interface here. Why would you need to do this instead of just the attribute names?

Based on your example, it looks like you're trying to partially manage the routes on a route table? For that use case I think we should go for a separate aws_route resource.

[robzienert]

Not exposing the state ID is fine, I was just thinking if people wanted to ignore an individual list item - but that would certainly be better suited with a join resource like aws_route. Good call.

[pmoust]

Would love to see that landing in 0.6.4, thanks for your efforts

[robzienert]

PR updated with a context test.

[phinze]

Looks good! Thanks for all your work on this, @robzienert 🙇

[berset]

Finally :)

[ghost]

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