support -html flag to render output as HTML

This addresses issue #69 to support HTML output.

This also...

- updates the README usage docs
- validates that multiple, conflicting format flags are not provided
- fixes a bug in the tests to properly validate expected tf-summarize errors

Signed-off-by: Mike Ball <mikedball@gmail.com>

README.md

@@ -110,10 +110,16 @@ Usage of tf-summarize [args] [tf-plan.json|tfplan]
 
   -draw
         [Optional, used only with -tree or -separate-tree] draw trees instead of plain tree
+  -html
+        [Optional] print changes in html format
+  -json
+        [Optional] print changes in json format
+  -md
+        [Optional, used only with table view] output table as markdown
   -out string
         [Optional] write output to file
   -separate-tree
-        [Optional] print changes in tree format for each add/delete/change/recreate changes
+        [Optional] print changes in tree format for add/delete/change/recreate changes
   -tree
         [Optional] print changes in tree format
   -v    print version

main.go

@@ -18,6 +18,7 @@ func main() {
 	printVersion := flag.Bool("v", false, "print version")
 	tree := flag.Bool("tree", false, "[Optional] print changes in tree format")
 	json := flag.Bool("json", false, "[Optional] print changes in json format")
+	html := flag.Bool("html", false, "[Optional] print changes in html format")
 	separateTree := flag.Bool("separate-tree", false, "[Optional] print changes in tree format for add/delete/change/recreate changes")
 	drawable := flag.Bool("draw", false, "[Optional, used only with -tree or -separate-tree] draw trees instead of plain tree")
 	md := flag.Bool("md", false, "[Optional, used only with table view] output table as markdown")
@@ -35,7 +36,7 @@ func main() {
 	}
 
 	args := flag.Args()
-	err := validateFlags(*tree, *separateTree, *drawable, *md, args)
+	err := validateFlags(*tree, *separateTree, *drawable, *md, *json, *html, args)
 	logIfErrorAndExit("invalid input flags: %s\n", err, flag.Usage)
 
 	newReader, err := reader.CreateReader(args)
@@ -52,7 +53,7 @@ func main() {
 
 	terraformstate.FilterNoOpResources(&terraformState)
 
-	newWriter := writer.CreateWriter(*tree, *separateTree, *drawable, *md, *json, terraformState)
+	newWriter := writer.CreateWriter(*tree, *separateTree, *drawable, *md, *json, *html, terraformState)
 
 	var outputFile io.Writer = os.Stdout
 
@@ -83,7 +84,7 @@ func logIfErrorAndExit(format string, err error, callback func()) {
 	}
 }
 
-func validateFlags(tree, separateTree, drawable bool, md bool, args []string) error {
+func validateFlags(tree, separateTree, drawable bool, md bool, json bool, html bool, args []string) error {
 	if tree && md {
 		return fmt.Errorf("both -tree and -md should not be provided")
 	}
@@ -96,8 +97,23 @@ func validateFlags(tree, separateTree, drawable bool, md bool, args []string) er
 	if !tree && !separateTree && drawable {
 		return fmt.Errorf("drawable should be provided with -tree or -seperate-tree")
 	}
+	if multipleTrueVals(md, json, html) {
+		return fmt.Errorf("only one of -md, -json, or -html should be provided")
+	}
 	if len(args) > 1 {
 		return fmt.Errorf("only one argument is allowed which is filename, but got %v", args)
 	}
 	return nil
 }
+
+func multipleTrueVals(vals ...bool) bool {
+	v := []bool{}
+
+	for _, val := range vals {
+		if val {
+			v = append(v, val)
+		}
+	}
+
+	return len(v) > 1
+}

main_test.go

@@ -61,13 +61,20 @@ func TestTFSummarize(t *testing.T) {
 	}, {
 		command:        fmt.Sprintf("cat example/tfplan.json | ./%s -md", testExecutable),
 		expectedOutput: "basic.txt",
+	}, {
+		command:        fmt.Sprintf("cat example/tfplan.json | ./%s -html", testExecutable),
+		expectedOutput: "basic.html",
+	}, {
+		command:        fmt.Sprintf("cat example/tfplan.json | ./%s -md -html", testExecutable),
+		expectedError:  fmt.Errorf("exit status 1"),
+		expectedOutput: "multiple_format_flags_error.txt",
 	}}
 
 	for _, test := range tests {
 		t.Run(fmt.Sprintf("when tf-summarize is passed '%q'", test.command), func(t *testing.T) {
-			output, err := exec.Command("/bin/sh", "-c", test.command).CombinedOutput()
-			if err != nil && test.expectedError == nil {
-				t.Errorf("expected '%s' not to error; got '%v'", test.command, err)
+			output, cmdErr := exec.Command("/bin/sh", "-c", test.command).CombinedOutput()
+			if cmdErr != nil && test.expectedError == nil {
+				t.Errorf("expected '%s' not to error; got '%v'", test.command, cmdErr)
 			}
 
 			b, err := os.ReadFile(fmt.Sprintf("testdata/%s", test.expectedOutput))
@@ -77,12 +84,12 @@ func TestTFSummarize(t *testing.T) {
 
 			expected := string(b)
 
-			if test.expectedError != nil && err == nil {
-				t.Errorf("expected error '%s'; got '%v'", test.expectedError.Error(), err)
+			if test.expectedError != nil && cmdErr == nil {
+				t.Errorf("expected error '%s'; got '%v'", test.expectedError.Error(), cmdErr)
 			}
 
-			if test.expectedError != nil && err != nil && test.expectedError.Error() != err.Error() {
-				t.Errorf("expected error '%s'; got '%v'", test.expectedError.Error(), err.Error())
+			if test.expectedError != nil && cmdErr != nil && test.expectedError.Error() != cmdErr.Error() {
+				t.Errorf("expected error '%s'; got '%v'", test.expectedError.Error(), cmdErr.Error())
 			}
 
 			if string(output) != expected {

testdata/basic.html

@@ -0,0 +1,20 @@
+<table>
+  <tr>
+    <th>CHANGE</th>
+    <th>RESOURCE</th>
+  </tr>
+  <tr>
+    <td>add</td>
+    <td>
+      <ul>
+        <li>github_repository.terraform_plan_summary</li>
+        <li>module.github["demo-repository"].github_branch.development</li>
+        <li>module.github["demo-repository"].github_branch.main</li>
+        <li>module.github["demo-repository"].github_repository.repository</li>
+        <li>module.github["terraform-plan-summary"].github_branch.development</li>
+        <li>module.github["terraform-plan-summary"].github_branch.main</li>
+        <li>module.github["terraform-plan-summary"].github_repository.repository</li>
+      </ul>
+    </td>
+  </tr>
+</table>

testdata/multiple_format_flags_error.txt

@@ -0,0 +1,19 @@
+invalid input flags: only one of -md, -json, or -html should be provided
+
+Usage of ./tf-summarize-test [args] [tf-plan.json|tfplan]
+
+  -draw
+    	[Optional, used only with -tree or -separate-tree] draw trees instead of plain tree
+  -html
+    	[Optional] print changes in html format
+  -json
+    	[Optional] print changes in json format
+  -md
+    	[Optional, used only with table view] output table as markdown
+  -out string
+    	[Optional] write output to file
+  -separate-tree
+    	[Optional] print changes in tree format for add/delete/change/recreate changes
+  -tree
+    	[Optional] print changes in tree format
+  -v	print version

writer/html.go

@@ -0,0 +1,50 @@
+package writer
+
+import (
+	"io"
+	"path"
+	"text/template"
+
+	"github.com/dineshba/tf-summarize/terraformstate"
+)
+
+// HTMLWriter is a Writer that writes HTML.
+type HTMLWriter struct {
+	ResourceChanges map[string]terraformstate.ResourceChanges
+	OutputChanges   map[string][]string
+}
+
+// Write outputs the HTML summary to the io.Writer it's passed.
+func (t HTMLWriter) Write(writer io.Writer) error {
+	templatesDir := "templates"
+	rcTmpl := "resourceChanges.html"
+	tmpl, err := template.New(rcTmpl).ParseFS(templates, path.Join(templatesDir, rcTmpl))
+	if err != nil {
+		return err
+	}
+
+	err = tmpl.Execute(writer, t)
+	if err != nil {
+		return err
+	}
+
+	if !hasOutputChanges(t.OutputChanges) {
+		return nil
+	}
+
+	ocTmpl := "outputChanges.html"
+	outputTmpl, err := template.New(ocTmpl).ParseFS(templates, path.Join(templatesDir, ocTmpl))
+	if err != nil {
+		return err
+	}
+
+	return outputTmpl.Execute(writer, t)
+}
+
+// NewHTMLWriter returns a new HTMLWriter with the configuration it's passed.
+func NewHTMLWriter(changes map[string]terraformstate.ResourceChanges, outputChanges map[string][]string) Writer {
+	return HTMLWriter{
+		ResourceChanges: changes,
+		OutputChanges:   outputChanges,
+	}
+}

writer/table.go

@@ -44,7 +44,7 @@ func (t TableWriter) Write(writer io.Writer) error {
 	table.Render()
 
 	// Disable the Output Summary if there are no outputs to display
-	if len(t.outputChanges["add"]) > 0 || len(t.outputChanges["delete"]) > 0 || len(t.outputChanges["update"]) > 0 {
+	if hasOutputChanges(t.outputChanges) {
 		tableString = make([][]string, 0, 4)
 		for _, change := range tableOrder {
 			changedOutputs := t.outputChanges[change]

writer/templates/outputChanges.html

@@ -0,0 +1,14 @@
+<table>
+  <tr>
+    <th>CHANGE</th>
+    <th>OUTPUT</th>
+  </tr>{{ range $change, $outputs := .OutputChanges }}{{ $length := len $outputs }}{{ if gt $length 0 }}
+  <tr>
+    <td>{{ $change }}</td>
+    <td>
+      <ul>{{ range $i, $o := $outputs }}
+        <li>{{ $o }}</li>{{ end }}
+      </ul>
+    </td>
+  </tr>{{ end }}{{ end }}
+</table>

writer/templates/resourceChanges.html

@@ -0,0 +1,14 @@
+<table>
+  <tr>
+    <th>CHANGE</th>
+    <th>RESOURCE</th>
+  </tr>{{ range $change, $resources := .ResourceChanges }}{{ $length := len $resources }}{{ if gt $length 0 }}
+  <tr>
+    <td>{{ $change }}</td>
+    <td>
+      <ul>{{ range $i, $r := $resources }}
+        <li>{{ $r.Address }}</li>{{ end }}
+      </ul>
+    </td>
+  </tr>{{ end }}{{ end }}
+</table>

writer/util.go

@@ -0,0 +1,21 @@
+package writer
+
+import "embed"
+
+// Embed the templates directory in the compiled binary.
+//
+//go:embed templates
+var templates embed.FS
+
+func hasOutputChanges(opChanges map[string][]string) bool {
+	hasChanges := false
+
+	for _, v := range opChanges {
+		if len(v) > 0 {
+			hasChanges = true
+			break
+		}
+	}
+
+	return hasChanges
+}

writer/writer.go

@@ -11,8 +11,7 @@ type Writer interface {
 	Write(writer io.Writer) error
 }
 
-func CreateWriter(tree, separateTree, drawable, mdEnabled, json bool, plan tfjson.Plan) Writer {
-
+func CreateWriter(tree, separateTree, drawable, mdEnabled, json, html bool, plan tfjson.Plan) Writer {
 	if tree {
 		return NewTreeWriter(plan.ResourceChanges, drawable)
 	}
@@ -22,6 +21,9 @@ func CreateWriter(tree, separateTree, drawable, mdEnabled, json bool, plan tfjso
 	if json {
 		return NewJSONWriter(plan.ResourceChanges)
 	}
+	if html {
+		return NewHTMLWriter(terraformstate.GetAllResourceChanges(plan), terraformstate.GetAllOutputChanges(plan))
+	}
 
 	return NewTableWriter(terraformstate.GetAllResourceChanges(plan), terraformstate.GetAllOutputChanges(plan), mdEnabled)
 }