terraform: support graphing modules

.gitignore

@@ -6,6 +6,7 @@ terraform.tfstate
 bin/
 config/y.go
 config/y.output
+modules-dev/
 pkg/
 vendor/
 website/.vagrant

command/graph.go

@@ -16,9 +16,12 @@ type GraphCommand struct {
 }
 
 func (c *GraphCommand) Run(args []string) int {
+	var moduleDepth int
+
 	args = c.Meta.process(args, false)
 
 	cmdFlags := flag.NewFlagSet("graph", flag.ContinueOnError)
+	cmdFlags.IntVar(&moduleDepth, "module-depth", 0, "module-depth")
 	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
 	if err := cmdFlags.Parse(args); err != nil {
 		return 1
@@ -55,7 +58,11 @@ func (c *GraphCommand) Run(args []string) int {
 		return 1
 	}
 
-	c.Ui.Output(terraform.GraphDot(g))
+	opts := &terraform.GraphDotOpts{
+		ModuleDepth: moduleDepth,
+	}
+
+	c.Ui.Output(terraform.GraphDot(g, opts))
 
 	return 0
 }
@@ -73,6 +80,11 @@ Usage: terraform graph [options] PATH
   read this format is GraphViz, but many web services are also available
   to read this format.
 
+Options:
+
+  -module-depth=n      The maximum depth to expand modules. By default this is
+                       zero, which will not expand modules at all.
+
 `
 	return strings.TrimSpace(helpText)
 }

terraform/graph_dot.go

@@ -2,17 +2,34 @@ package terraform
 
 import (
 	"bytes"
+	"bufio"
 	"fmt"
+	"strings"
 
 	"github.com/hashicorp/terraform/depgraph"
 	"github.com/hashicorp/terraform/digraph"
 )
 
+// GraphDotOpts are options for turning a graph into dot format.
+type GraphDotOpts struct {
+	// ModuleDepth is the depth of modules to expand. Zero is no expansion,
+	// one expands the first set of modules, etc. If this is set to -1, then
+	// all modules are expanded.
+	ModuleDepth int
+
+	// Depth is an internal track of what depth we're at within
+	// the graph, used to control indentation and other such things.
+	depth int
+}
+
 // GraphDot returns the dot formatting of a visual representation of
 // the given Terraform graph.
-func GraphDot(g *depgraph.Graph) string {
+func GraphDot(g *depgraph.Graph, opts *GraphDotOpts) string {
 	buf := new(bytes.Buffer)
-	buf.WriteString("digraph {\n")
+
+	if opts.depth == 0 {
+		buf.WriteString("digraph {\n")
+	}
 
 	// Determine and add the title
 	// graphDotTitle(buf, g)
@@ -23,7 +40,13 @@ func GraphDot(g *depgraph.Graph) string {
 	// Add all the resource providers
 	graphDotAddResourceProviders(buf, g)
 
-	buf.WriteString("}\n")
+	// Add all the modules
+	graphDotAddModules(buf, g, opts)
+
+	if opts.depth == 0 {
+		buf.WriteString("}\n")
+	}
+
 	return buf.String()
 }
 
@@ -39,6 +62,65 @@ func graphDotAddRoot(buf *bytes.Buffer, n *depgraph.Noun) {
 	}
 }
 
+func graphDotAddModules(buf *bytes.Buffer, g *depgraph.Graph, opts *GraphDotOpts) {
+	for _, n := range g.Nouns {
+		_, ok := n.Meta.(*GraphNodeModule)
+		if !ok {
+			continue
+		}
+
+		if opts.ModuleDepth == opts.depth {
+			// We're not expanding, so just add the module on its own
+			graphDotAddModuleSingle(buf, n, opts)
+		} else {
+			// We're expanding
+			graphDotAddModuleExpand(buf, n, opts)
+		}
+	}
+}
+
+func graphDotAddModuleExpand(
+	buf *bytes.Buffer, n *depgraph.Noun, opts *GraphDotOpts) {
+	m := n.Meta.(*GraphNodeModule)
+	tab := strings.Repeat("\t", opts.depth+1)
+
+	// Wrap ourselves in a subgraph
+	buf.WriteString(fmt.Sprintf("%ssubgraph \"%s\" {\n", tab, n.Name))
+	defer buf.WriteString(fmt.Sprintf("%s}\n", tab))
+
+	// Graph the subgraph just as we would any other graph
+	subOpts := *opts
+	subOpts.depth++
+	subStr := GraphDot(m.Graph, &subOpts)
+
+	// Tab all the lines of the subgraph
+	s := bufio.NewScanner(strings.NewReader(subStr))
+	for s.Scan() {
+		buf.WriteString(fmt.Sprintf("%s%s\n", tab, s.Text()))
+	}
+}
+
+func graphDotAddModuleSingle(
+	buf *bytes.Buffer, n *depgraph.Noun, opts *GraphDotOpts) {
+	tab := strings.Repeat("\t", opts.depth+1)
+
+	//m := n.Meta.(*GraphNodeModule)
+
+	// Create this node.
+	buf.WriteString(fmt.Sprintf("%s\"%s\" [\n", tab, n))
+	buf.WriteString(fmt.Sprintf("%s\tshape=component\n", tab))
+	buf.WriteString(fmt.Sprintf("%s];\n", tab))
+
+	for _, e := range n.Edges() {
+		target := e.Tail()
+		buf.WriteString(fmt.Sprintf(
+			"%s\"%s\" -> \"%s\";\n",
+			tab,
+			n,
+			target))
+	}
+}
+
 func graphDotAddResources(buf *bytes.Buffer, g *depgraph.Graph) {
 	// Determine if we have diffs. If we do, then we're graphing a
 	// plan, which alters our graph a bit.