r/aws_instance: Add support for launch template

[gordonbondon]

Fixes #4264

Changes proposed in this pull request:

• Add support for launch template in instance resource

Output from acceptance testing:

make testacc TEST=./aws TESTARGS='-run=TestAccAWSInstance_LaunchTemplate'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSInstance_LaunchTemplate -timeout 120m
=== RUN   TestAccAWSInstance_LaunchTemplate
--- PASS: TestAccAWSInstance_LaunchTemplate (430.43s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	430.769s

A couple of notes:

1. Template is used only once when instance is created, so later it should be possible to change instance parameters via direct attributes.
2. Using template and overriding root volume device should check template ami and use its device.
3. We can get launch template details only from instance tags
4. I did not want to implement complicated logic of whether changes in template should force instance recreation or not, so any change to template version or id/name will force new instance.
5. But if $Default or $Latest switch to a version that is actually the same, this will not force recreation.

Maybe there is a better way to do this CustomDiff?

[gordonbondon]

Rebased and resolved conflicts.

[gordonbondon]

Rebased and resolved conflicts.

[Jamie-BitFlight]

Is this scheduled to be added after the 0.12 release?

[gordonbondon]

Rerun acc tests after rebase:

make testacc TEST=./aws TESTARGS='-run=TestAccAWSInstance_LaunchTemplate'
Password:
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSInstance_LaunchTemplate -timeout 120m
=== RUN   TestAccAWSInstance_LaunchTemplate
--- PASS: TestAccAWSInstance_LaunchTemplate (568.05s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	568.093s

[dshmelev]

Hi! Still not merged? This is important change. Release please.

[gordonbondon]

It's been some time so I decided to rebase and retest. All looks fine:

→ make testacc TEST=./aws TESTARGS='-run=TestAccAWSInstance_LaunchTemplate'
Password:
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -parallel 20 -run=TestAccAWSInstance_LaunchTemplate -timeout 120m
=== RUN   TestAccAWSInstance_LaunchTemplate
--- PASS: TestAccAWSInstance_LaunchTemplate (848.09s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	848.141s

@bflad anything else I need to do with this PR?

[alexandrst88]

@sftim, @bflad hi! could you please provide ETA about merge this PR? Thanks!

[sftim]

Hi @alexandrst88
A while ago I provided some informal feedback on this PR. I'm afraid I don't actually know what the route to approval looks like for this repo.

It looks like https://github.com/terraform-providers/terraform-provider-aws/blob/master/.github/CONTRIBUTING.md explains what you'd need to do, and what the Terraform core team need to do.

[jasonneurohr]

Is there any update on this as I'm keen to use this functionality?

[sftim]

It looks like the fork this is from might have disappeared. Maybe someone else would like to pick up the baton?

[gordonbondon]

Oops, I've completely forgotten about this PR and deleted my fork. I'll probably have to create new PR to rebase this one.

[jasonneurohr]

Oops, I've completely forgotten about this PR and deleted my fork. I'll probably have to create new PR to rebase this one.

I'm happy to test it out and or contribute if needed - I'm a bit green to Go though :)

[gordonbondon]

I've opened new PR at #10807

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!