Add the ability to specify terraform-pipeline starting execution workspace directory

[vincentclee]

Currently, we have the TerraformDirectoryPlugin which allows terraform-pipeline to do this:

TerraformDirectoryPlugin.withDirectory("app1/terraform").init()

terraform <command> app1/terraform
...

What i would like terraform-pipeline to support:

TerraformStartingDirectoryPlugin.withDirectory("appQ/terraform").init()

cd appQ/terraform
terraform <command> .

This is important with monolithic pipeline repo's where the .terraform-version flat file is only read from the root of the project tree when using the TerraformDirectoryPlugin.

[kmanning]

Seems like a good UseCase. In thinking through this, we'll have to be careful about how other TerraformCommandPlugins interact with this new UseCase. Lots of plugins decorate the front of the command (eg: awssume/parameter-store-exec), and the command itself is treated as a single shell step. What you're looking for is a separate shell step.

[kmanning]

I don't know that TerraformDirectoryPlugin is so inappropriately named for this UseCase. I wonder if it could offer both behaviors with the same plugin?

TerraformDirectoryPlugin.withDirectory("app1/terraform").init()

vs

TerraformDirectoryPlugin.withStartDirectory("app1/terraform").init()

or something like

TerraformDirectoryPlugin.withDirectory("app1/terraform").withCdCommand().init()

I hate the name withCdCommand, but something that toggles one or the other behavior off and on.

[vincentclee]

I like option one.
Extend TerraformDirectoryPlugin to support the withStartDirectory method

[kmanning]

Note: Change in terraform 0.14 and 0.15 related to subdirectories. https://www.terraform.io/docs/cli/commands/plan.html#passing-a-different-configuration-directory

[vincentclee]

This is officially needed on terraform 0.15 and later.

[kdibenedetto]

Yeah, I went to use tf 1.0.1 and was hit with this issue.