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

@@ -70,6 +70,7 @@ 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

@@ -14,6 +14,7 @@ type Parser interface {
 // ParseResult represents the result of parsed terraform execution
 type ParseResult struct {
 	Result   string
+	Action   string
 	ExitCode int
 	Error    error
 }
@@ -30,8 +31,9 @@ type FmtParser struct {
 
 // PlanParser is a parser for terraform plan
 type PlanParser struct {
-	Pass *regexp.Regexp
-	Fail *regexp.Regexp
+	Pass   *regexp.Regexp
+	Action *regexp.Regexp
+	Fail   *regexp.Regexp
 }
 
 // ApplyParser is a parser for terraform apply
@@ -55,8 +57,9 @@ 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: )`),
 	}
 }
 
@@ -103,21 +106,30 @@ 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")
 	}
 	return ParseResult{
 		Result:   result,
+		Action:   action,
 		ExitCode: exitCode,
 		Error:    nil,
 	}

terraform/parser_test.go

@@ -251,7 +251,21 @@ func TestPlanParserParse(t *testing.T) {
 			name: "plan ok pattern",
 			body: planSuccessResult,
 			result: ParseResult{
-				Result:   "Plan: 1 to add, 0 to change, 0 to destroy.",
+				Result: "Plan: 1 to add, 0 to change, 0 to destroy.",
+				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

@@ -111,6 +111,7 @@ type FmtTemplate struct {
 // PlanTemplate is a default template for terraform plan
 type PlanTemplate struct {
 	Template string
+	Action   string
 
 	CommonTemplate
 }
@@ -182,7 +183,7 @@ func (t *DefaultTemplate) Execute() (resp string, err error) {
 	return resp, err
 }
 
-// Execute binds the execution result of terraform fmt into tepmlate
+// Execute binds the execution result of terraform fmt into template
 func (t *FmtTemplate) Execute() (resp string, err error) {
 	tpl, err := template.New("fmt").Parse(t.Template)
 	if err != nil {
@@ -202,7 +203,7 @@ func (t *FmtTemplate) Execute() (resp string, err error) {
 	return resp, err
 }
 
-// Execute binds the execution result of terraform plan into tepmlate
+// Execute binds the execution result of terraform plan into template
 func (t *PlanTemplate) Execute() (resp string, err error) {
 	tpl, err := template.New("plan").Parse(t.Template)
 	if err != nil {
@@ -212,6 +213,7 @@ func (t *PlanTemplate) Execute() (resp string, err error) {
 	if err := tpl.Execute(&b, map[string]interface{}{
 		"Title":   t.Title,
 		"Message": t.Message,
+		"Action":  t.Action,
 		"Result":  t.Result,
 		"Body":    t.Body,
 		"Link":    t.Link,
@@ -222,7 +224,7 @@ func (t *PlanTemplate) Execute() (resp string, err error) {
 	return resp, err
 }
 
-// Execute binds the execution result of terraform apply into tepmlate
+// Execute binds the execution result of terraform apply into template
 func (t *ApplyTemplate) Execute() (resp string, err error) {
 	tpl, err := template.New("apply").Parse(t.Template)
 	if err != nil {