Parse a state action string like a shell

[minamijoyo]

Fixes #5
We cannot simply split it by space because the address of resource can contain spaces.
We should parse it like a shell with go-shellwords.

[minamijoyo]

Given the following configuration:

terraform {
  required_version = "0.13.5"

  required_providers {
    docker = {
      source  = "terraform-providers/docker"
      version = "2.7.2"
    }
  }
}

resource "docker_image" "nginx" {
  name         = "nginx:latest"
  keep_locally = false
}

# resource "docker_container" "nginx" {
#   image = docker_image.nginx.latest
#   name  = "example"
# }

resource "docker_container" "nginx" {
  for_each = {
    "This is an example" = "example"
  }

  image = docker_image.nginx.latest
  name  = each.value
}

A migration file is the following. Note that we need to escape double-quote ( \" ). It's a HCL limitation.

migration "state" "test" {
  dir = "tmp/test5"
  actions = [
    "mv docker_container.nginx 'docker_container.nginx[\"This is an example\"]'",
  ]
}

Run the tfmigrate plan command:

[tfmigrate@fix-iss-5|✔]$ TFMIGRATE_LOG=DEBUG bin/tfmigrate plan tmp/test5/state_mv.hcl
2020/11/05 22:11:51 [DEBUG] [main] start: bin/tfmigrate plan tmp/test5/state_mv.hcl
2020/11/05 22:11:51 [DEBUG] [main] tfmigrate version: 0.1.0
2020/11/05 22:11:51 [DEBUG] [command] option: &tfmigrate.MigratorOption{ExecPath:""}
2020/11/05 22:11:51 [INFO] [command] read migration file: tmp/test5/state_mv.hcl
2020/11/05 22:11:51 [DEBUG] [command] parse migration file: "migration \"state\" \"test\" {\n  dir = \"tmp/test5\"\n  actions = [\n    \"mv docker_container.nginx 'docker_container.nginx[\"This is an example\"]'\",\n  ]\n}\n"
failed to decode migration file: tmp/test5/state_mv.hcl, err: tmp/test5/state_mv.hcl:4,57-61: Missing item separator; Expected a comma to mark the beginning of the next item.
[tfmigrate@fix-iss-5|✔]$ TFMIGRATE_LOG=DEBUG bin/tfmigrate plan tmp/test5/state_mv.hcl
2020/11/05 22:12:13 [DEBUG] [main] start: bin/tfmigrate plan tmp/test5/state_mv.hcl
2020/11/05 22:12:13 [DEBUG] [main] tfmigrate version: 0.1.0
2020/11/05 22:12:13 [DEBUG] [command] option: &tfmigrate.MigratorOption{ExecPath:""}
2020/11/05 22:12:13 [INFO] [command] read migration file: tmp/test5/state_mv.hcl
2020/11/05 22:12:13 [DEBUG] [command] parse migration file: "migration \"state\" \"test\" {\n  dir = \"tmp/test5\"\n  actions = [\n    \"mv docker_container.nginx 'docker_container.nginx[\\\"This is an example\\\"]'\",\n  ]\n}\n"
2020/11/05 22:12:13 [INFO] [command] new migrator: &config.StateMigratorConfig{Dir:"tmp/test5", Actions:[]string{"mv docker_container.nginx 'docker_container.nginx[\"This is an example\"]'"}}
2020/11/05 22:12:13 [INFO] [migrator] start state migrator plan
2020/11/05 22:12:14 [DEBUG] [executor@tmp/test5]$ terraform version
2020/11/05 22:12:14 [INFO] [migrator@tmp/test5] terraform version: 0.13.5
2020/11/05 22:12:14 [INFO] [migrator@tmp/test5] initialize work dir
2020/11/05 22:12:15 [DEBUG] [executor@tmp/test5]$ terraform init -input=false -no-color
2020/11/05 22:12:15 [INFO] [migrator@tmp/test5] get the current remote state
2020/11/05 22:12:16 [DEBUG] [executor@tmp/test5]$ terraform state pull
2020/11/05 22:12:16 [INFO] [migrator@tmp/test5] override backend to local
2020/11/05 22:12:16 [INFO] [executor@tmp/test5] create an override file
2020/11/05 22:12:16 [INFO] [executor@tmp/test5] switch backend to local
2020/11/05 22:12:17 [DEBUG] [executor@tmp/test5]$ terraform init -input=false -no-color -reconfigure
2020/11/05 22:12:17 [INFO] [migrator@tmp/test5] compute a new state
2020/11/05 22:12:17 [DEBUG] [executor@tmp/test5]$ terraform state mv -state=/var/folders/zh/37j0y_pn2pzc295c19rpw2tw0000gp/T/tmp756235542 -backup=/dev/null docker_container.nginx docker_container.nginx["This is an example"]
2020/11/05 22:12:17 [INFO] [migrator@tmp/test5] check diffs
2020/11/05 22:12:19 [DEBUG] [executor@tmp/test5]$ terraform plan -state=/var/folders/zh/37j0y_pn2pzc295c19rpw2tw0000gp/T/tmp877907325 -out=/var/folders/zh/37j0y_pn2pzc295c19rpw2tw0000gp/T/tfplan340595896 -input=false -no-color -detailed-exitcode
2020/11/05 22:12:19 [INFO] [executor@tmp/test5] remove the override file
2020/11/05 22:12:19 [INFO] [executor@tmp/test5] switch back to remote
2020/11/05 22:12:19 [DEBUG] [executor@tmp/test5]$ terraform init -input=false -no-color -reconfigure
2020/11/05 22:12:19 [INFO] [migrator] state migrator plan success!

Looks good to me.