Re-adds support for setting tags on the default route table

[lorengordon]

Uses a data source to retrieve and preserve the routes
that are currently associated with the route table. This
works around prior problems with supporting this resource,
as described in #95.

Fixes #146

[lorengordon]

@antonbabenko this seemed pretty straightforward to address, after all.

[antonbabenko]

Please update README and maybe an example. See #111 for more.

I will try to look at this PR and test it on Monday, but can't promise.

[lorengordon]

I gated the resource on the manage_default_vpc variable. So as is, the manage-default-vpc example covers the resource. The default DHCP option set will get the same name tag as the default VPC, set with default_vpc_name. Seemed like a reasonable approach that parallels how tags are assigned to the other DHCP option sets.

And I did update the README already, at least to add the variable back to the table. I don't really see the default VPC covered anywhere else there, so I'm not sure what more you're looking for.

[stefansedich]

This would be handy for me, looks like it has been stalled for a loooong time, is there any desire to get it in?

[gillg]

Why use a data source ?
Route table ID is available by concat(aws_vpc.this.*.default_route_table_id, [""])[0] (see outputs)

[gillg]

I made a try outside VPC module, route argument is useless :

Moreover this version is more TF > 0.12 compliant:

resource "aws_default_route_table" "this" {
  count = "${var.manage_default_vpc ? 1 : 0}"

  default_route_table_id = concat(aws_vpc.this.*.default_route_table_id, [""])[0]
  tags = merge({
      Name = var.default_vpc_name
      Createdby = "AWS"
      Taggedby = "terraform"
    },
    var.tags,
    var.default_route_table_tags
  )
}

[gillg]

This feature seems usefull for lisibility of your infrastructure...
Maybe also, option manage_default_vpc is useless, VPC module should tag all its resources. It's what user wants.

To workaround, for now I made a resource outside vpc module

resource "aws_default_route_table" "default_table" {
  default_route_table_id = module.vpc.default_route_table_id
  tags = {
    Name = "my-vpc-name-default"
    Createdby = "AWS"
    Taggedby = "terraform"
  }
}

That's all, and now all my routes tables are tagged

[DrFaust92]

Hey @lorengordon, can you take a look at the comments left by @gillg?
it's worth to make this PR a more generic "manage the default route table" task. waiting for you response. if you no response is given ill continue this with branch from this.

[lorengordon]

@DrFaust92 haven't touched this in two years. feel free to take it over.

[github-actions]

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