feat(tf,plan): extract action part from terraform plan output.

**Why**
Sometimes we found the part about `Refreshing Terraform state in-memory prior to plan`
has too many lines that we do not need to care about in the code review. So make this
change can help us to focus on the action part that terraform plan is.

Author: Han Zhou

README.md

@@ -72,6 +72,7 @@ Placeholder | Usage
 ---|---
 `{{ .Title }}` | Like `## Plan result`
 `{{ .Message }}` | A string that can be set from CLI with `--message` option
+`{{ .Action }}` | Using in terraform plan, and matched leading message by parsing like `Terraform will perform the following actions:`
 `{{ .Result }}` | Matched result by parsing like `Plan: 1 to add` or `No changes`
 `{{ .Body }}` | The entire of Terraform execution result
 `{{ .Link }}` | The link of the build page on CI

terraform/parser.go

@@ -15,6 +15,7 @@ type Parser interface {
 type ParseResult struct {
 	Result     string
 	HasDestroy bool
+	Action     string
 	ExitCode   int
 	Error      error
 }
@@ -32,6 +33,7 @@ type FmtParser struct {
 // PlanParser is a parser for terraform plan
 type PlanParser struct {
 	Pass       *regexp.Regexp
+	Action     *regexp.Regexp
 	Fail       *regexp.Regexp
 	HasDestroy *regexp.Regexp
 }
@@ -57,8 +59,9 @@ func NewFmtParser() *FmtParser {
 // NewPlanParser is PlanParser initialized with its Regexp
 func NewPlanParser() *PlanParser {
 	return &PlanParser{
-		Pass: regexp.MustCompile(`(?m)^(Plan: \d|No changes.)`),
-		Fail: regexp.MustCompile(`(?m)^(Error: )`),
+		Pass:   regexp.MustCompile(`(?m)^(Plan: \d|No changes.)`),
+		Action: regexp.MustCompile(`(?m)^(An execution plan has been generated)`),
+		Fail:   regexp.MustCompile(`(?m)^(Error: )`),
 		// "0 to destroy" should be treated as "no destroy"
 		HasDestroy: regexp.MustCompile(`(?m)([1-9][0-9]* to destroy.)`),
 	}
@@ -107,16 +110,24 @@ func (p *PlanParser) Parse(body string) ParseResult {
 		}
 	}
 	lines := strings.Split(body, "\n")
-	var i int
-	var result, line string
+	var i, actionStartIdx int
+	var result, action, line string
 	for i, line = range lines {
+		if p.Action.MatchString(line) {
+			// action starts with the line: An execution plan...
+			actionStartIdx = i
+		}
 		if p.Pass.MatchString(line) || p.Fail.MatchString(line) {
 			break
 		}
 	}
 	switch {
 	case p.Pass.MatchString(line):
 		result = lines[i]
+		if actionStartIdx != 0 {
+			// action ends with the line above summary
+			action = strings.Join(trimLastNewline(lines[actionStartIdx:i]), "\n")
+		}
 	case p.Fail.MatchString(line):
 		result = strings.Join(trimLastNewline(lines[i:]), "\n")
 	}
@@ -126,6 +137,7 @@ func (p *PlanParser) Parse(body string) ParseResult {
 	return ParseResult{
 		Result:     result,
 		HasDestroy: hasDestroy,
+		Action:     action,
 		ExitCode:   exitCode,
 		Error:      nil,
 	}

terraform/parser_test.go

@@ -35,7 +35,7 @@ versions.tf
 --- old/versions.tf
 +++ new/versions.tf
 @@ -1,4 +1,4 @@
- 
+
  terraform {
 -  required_version     = ">= 0.12"
 +  required_version = ">= 0.12"
@@ -309,8 +309,22 @@ func TestPlanParserParse(t *testing.T) {
 			result: ParseResult{
 				Result:     "Plan: 1 to add, 0 to change, 0 to destroy.",
 				HasDestroy: false,
-				ExitCode:   0,
-				Error:      nil,
+				Action: `An execution plan has been generated and is shown below.
+Resource actions are indicated with the following symbols:
+  + create
+
+Terraform will perform the following actions:
+
+  + google_compute_global_address.my_another_project
+      id:         <computed>
+      address:    <computed>
+      ip_version: "IPV4"
+      name:       "my-another-project"
+      project:    "my-project"
+      self_link:  <computed>
+`,
+				ExitCode: 0,
+				Error:    nil,
 			},
 		},
 		{

terraform/template.go

@@ -102,11 +102,12 @@ type Template interface {
 
 // CommonTemplate represents template entities
 type CommonTemplate struct {
-	Title        string
-	Message      string
-	Result       string
-	Body         string
-	Link         string
+	Title   string
+	Message string
+	Action  string
+	Result  string
+	Body    string
+	Link    string
 	UseRawOutput bool
 }
 
@@ -278,6 +279,7 @@ func (t *DestroyWarningTemplate) Execute() (string, error) {
 	data := map[string]interface{}{
 		"Title":   t.Title,
 		"Message": t.Message,
+		"Action":  t.Action,
 		"Result":  t.Result,
 		"Body":    t.Body,
 		"Link":    t.Link,

terraform/template_test.go

@@ -450,6 +450,17 @@ message
 			},
 			resp: `a-b-c-d`,
 		},
+		{
+			template: `{{ .Title }}-{{ .Message }}-{{ .Action }}-{{ .Result }}-{{ .Body }}`,
+			value: CommonTemplate{
+				Title:   "a",
+				Message: "b",
+				Action:  "action",
+				Result:  "c",
+				Body:    "d",
+			},
+			resp: `a-b-action-c-d`,
+		},
 	}
 	for _, testCase := range testCases {
 		template := NewPlanTemplate(testCase.template)