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package terraform
import (
"fmt"
"log"
"runtime/debug"
"strings"
"github.com/hashicorp/terraform/dag"
)
// RootModuleName is the name given to the root module implicitly.
const RootModuleName = "root"
// RootModulePath is the path for the root module.
var RootModulePath = []string{RootModuleName}
// Graph represents the graph that Terraform uses to represent resources
// and their dependencies.
type Graph struct {
// Graph is the actual DAG. This is embedded so you can call the DAG
// methods directly.
dag.AcyclicGraph
// Path is the path in the module tree that this Graph represents.
// The root is represented by a single element list containing
// RootModuleName
Path []string
// debugName is a name for reference in the debug output. This is usually
// to indicate what topmost builder was, and if this graph is a shadow or
// not.
debugName string
}
func (g *Graph) DirectedGraph() dag.Grapher {
return &g.AcyclicGraph
}
// Walk walks the graph with the given walker for callbacks. The graph
// will be walked with full parallelism, so the walker should expect
// to be called in concurrently.
func (g *Graph) Walk(walker GraphWalker) error {
return g.walk(walker)
}
func (g *Graph) walk(walker GraphWalker) error {
// The callbacks for enter/exiting a graph
ctx := walker.EnterPath(g.Path)
defer walker.ExitPath(g.Path)
// Get the path for logs
path := strings.Join(ctx.Path(), ".")
// Determine if our walker is a panic wrapper
panicwrap, ok := walker.(GraphWalkerPanicwrapper)
if !ok {
panicwrap = nil // just to be sure
}
debugName := "walk-graph.json"
if g.debugName != "" {
debugName = g.debugName + "-" + debugName
}
debugBuf := dbug.NewFileWriter(debugName)
g.SetDebugWriter(debugBuf)
defer debugBuf.Close()
// Walk the graph.
var walkFn dag.WalkFunc
walkFn = func(v dag.Vertex) (rerr error) {
log.Printf("[DEBUG] vertex '%s.%s': walking", path, dag.VertexName(v))
g.DebugVisitInfo(v, g.debugName)
// If we have a panic wrap GraphWalker and a panic occurs, recover
// and call that. We ensure the return value is an error, however,
// so that future nodes are not called.
defer func() {
// If no panicwrap, do nothing
if panicwrap == nil {
return
}
// If no panic, do nothing
err := recover()
if err == nil {
return
}
// Modify the return value to show the error
rerr = fmt.Errorf("vertex %q captured panic: %s\n\n%s",
dag.VertexName(v), err, debug.Stack())
// Call the panic wrapper
panicwrap.Panic(v, err)
}()
walker.EnterVertex(v)
defer walker.ExitVertex(v, rerr)
// vertexCtx is the context that we use when evaluating. This
// is normally the context of our graph but can be overridden
// with a GraphNodeSubPath impl.
vertexCtx := ctx
if pn, ok := v.(GraphNodeSubPath); ok && len(pn.Path()) > 0 {
vertexCtx = walker.EnterPath(normalizeModulePath(pn.Path()))
defer walker.ExitPath(pn.Path())
}
// If the node is eval-able, then evaluate it.
if ev, ok := v.(GraphNodeEvalable); ok {
tree := ev.EvalTree()
if tree == nil {
panic(fmt.Sprintf(
"%s.%s (%T): nil eval tree", path, dag.VertexName(v), v))
}
// Allow the walker to change our tree if needed. Eval,
// then callback with the output.
log.Printf("[DEBUG] vertex '%s.%s': evaluating", path, dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("evaluating %T(%s)", v, path))
tree = walker.EnterEvalTree(v, tree)
output, err := Eval(tree, vertexCtx)
if rerr = walker.ExitEvalTree(v, output, err); rerr != nil {
return
}
}
// If the node is dynamically expanded, then expand it
if ev, ok := v.(GraphNodeDynamicExpandable); ok {
log.Printf(
"[DEBUG] vertex '%s.%s': expanding/walking dynamic subgraph",
path,
dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("expanding %T(%s)", v, path))
g, err := ev.DynamicExpand(vertexCtx)
if err != nil {
rerr = err
return
}
if g != nil {
// Walk the subgraph
if rerr = g.walk(walker); rerr != nil {
return
}
}
}
// If the node has a subgraph, then walk the subgraph
if sn, ok := v.(GraphNodeSubgraph); ok {
log.Printf(
"[DEBUG] vertex '%s.%s': walking subgraph",
path,
dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("subgraph: %T(%s)", v, path))
if rerr = sn.Subgraph().(*Graph).walk(walker); rerr != nil {
return
}
}
return nil
}
return g.AcyclicGraph.Walk(walkFn)
}
|