WIP Spot bids as separate resource

[dalehamel]

An alternative solution to #1339 based on comments from #2095

This notably moves spot bids to be their own resource, and personally I think it's much cleaner.

The major drawback that would need to be covered in refactoring though is that they share lots of attributes, and those would need to be refactored to DRY things up, but as mentioned in comments on the other PR, I think this probably the most favorable solution.

One thing I'm not very happy with is that attributes provided by aws_spot_bid and required by aws_instance have to be specified twice.

A sample terraform file is provided below, which illustrates this problem:

resource "aws_spot_bid" "test" {
    ami = "ami-50948838"
    instance_type = "m1.small"
    spot_price = "0.05"
    spot_persist = true
    key_name = "dale.hamel"
    tags {
        Name = "HelloWorld"
    }
}

resource "aws_instance" "web" {
    ami = "${aws_spot_bid.test.ami}"
    instance_type = "${aws_spot_bid.test.instance_type}"
    spot_request = "${aws_spot_bid.test.id}"
}

This "works" but there are lots of FIXMEs and no tests, so this should be considered another rough-cut for review of the concept.

Between this and the other PR, the two major options of either having spot instances be special types of instances, verses having spot bids be their own resource are covered. I can't think of a third option, but perhaps there is one?

I'm closing the other PR in favor of this one, if we decide we don't like this approach we can reopen it.

summary of changes:

• Spot bid logic moved almost entirely out to it's own resource
• aws instances can take a spot_request as a parameter. If they do, then they don't launch an on demand instance, and instead expect that a spot instance is ready for them.

@cbednarski @mitchellh @catsby for review

[mitchellh]

@catsby and I looked at this and we're back in the camp that we liked your previous PR, just remove the fallback for now. I think with that it'd be good to merge. Sorry for the back and forth.

I think the spot_request field interaction on aws_instance is very strange. It adds conditional logic to Terraform configs without actually generalizing it like #1604.

Can you revert back to what you had before? Thanks! (Just open the PR agains ince its pretty diff)

[dalehamel]

🆒

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