Change cloudbuild trigger's args field to be a list.

Right now, cloudbuild trigger's args field expects a string, then splits
that string on spaces to get the list the API wants. This doesn't do
proper quote escaping, however, and creates problems, which led to
hashicorp/terraform-provider-google#2101.

This change turns it into a list instead of a string, so the user can
take care of the parsing and escaping themselves.

This is a breaking change, and should only go out with 2.0.0. We talked
about the transition paths available to us, and this seemed the most
reasonable.

third_party/terraform/resources/resource_cloudbuild_build_trigger.go

@@ -64,8 +64,11 @@ func resourceCloudBuildTrigger() *schema.Resource {
 										Optional: true,
 									},
 									"args": &schema.Schema{
-										Type:     schema.TypeString,
+										Type:     schema.TypeList,
 										Optional: true,
+										Elem: &schema.Schema{
+											Type: schema.TypeString,
+										},
 									},
 								},
 							},
@@ -294,7 +297,7 @@ func expandCloudbuildBuildTriggerBuild(d *schema.ResourceData) *cloudbuild.Build
 			Name: d.Get(fmt.Sprintf("build.0.step.%d.name", s)).(string),
 		}
 		if v, ok := d.GetOk(fmt.Sprintf("build.0.step.%d.args", s)); ok {
-			step.Args = strings.Split(v.(string), " ")
+			step.Args = convertStringArr(v.([]interface{}))
 		}
 		build.Steps = append(build.Steps, step)
 	}
@@ -317,7 +320,7 @@ func flattenCloudbuildBuildTriggerBuild(d *schema.ResourceData, config *Config,
 		for i, step := range b.Steps {
 			steps[i] = map[string]interface{}{}
 			steps[i]["name"] = step.Name
-			steps[i]["args"] = strings.Join(step.Args, " ")
+			steps[i]["args"] = convertStringArrToInterface(step.Args)
 		}
 		flattened[0]["step"] = steps
 	}

third_party/terraform/tests/resource_cloudbuild_build_trigger_test.go

@@ -204,15 +204,15 @@ resource "google_cloudbuild_trigger" "build_trigger" {
     tags = ["team-a", "service-b"]
     step {
       name = "gcr.io/cloud-builders/gsutil"
-      args = "cp gs://mybucket/remotefile.zip localfile.zip "
+      args = ["cp", "gs://mybucket/remotefile.zip", "localfile.zip"]
     }
     step {
       name = "gcr.io/cloud-builders/go"
-      args = "build my_package"
+      args = ["build", "my_package"]
     }
     step {
       name = "gcr.io/cloud-builders/docker"
-      args = "build -t gcr.io/$PROJECT_ID/$REPO_NAME:$COMMIT_SHA -f Dockerfile ."
+      args = ["build", "-t", "gcr.io/$PROJECT_ID/$REPO_NAME:$COMMIT_SHA", "-f", "Dockerfile ."]
     }
   }
 }
@@ -253,19 +253,19 @@ resource "google_cloudbuild_trigger" "build_trigger" {
     tags = ["team-a", "service-b", "updated"]
     step {
       name = "gcr.io/cloud-builders/gsutil"
-      args = "cp gs://mybucket/remotefile.zip localfile-updated.zip "
+      args = ["cp", "gs://mybucket/remotefile.zip", "localfile-updated.zip "]
     }
     step {
       name = "gcr.io/cloud-builders/go"
-      args = "build my_package_updated"
+      args = ["build", "my_package_updated"]
     }
     step {
       name = "gcr.io/cloud-builders/docker"
-      args = "build -t gcr.io/$PROJECT_ID/$REPO_NAME:$SHORT_SHA -f Dockerfile ."
+      args = ["build", "-t", "gcr.io/$PROJECT_ID/$REPO_NAME:$SHORT_SHA", "-f", "Dockerfile ."]
     }
     step {
       name = "gcr.io/$PROJECT_ID/$REPO_NAME:$SHORT_SHA"
-      args = "test"
+      args = ["test"]
     }
   }
 }