/
graph.go
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/
graph.go
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package terraform
import (
"fmt"
"log"
"github.com/hashicorp/terraform/tfdiags"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/dag"
)
// 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.
Path addrs.ModuleInstance
// 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) tfdiags.Diagnostics {
return g.walk(walker)
}
func (g *Graph) walk(walker GraphWalker) tfdiags.Diagnostics {
// The callbacks for enter/exiting a graph
ctx := walker.EnterPath(g.Path)
defer walker.ExitPath(g.Path)
// Get the path for logs
path := ctx.Path().String()
debugName := "walk-graph.json"
if g.debugName != "" {
debugName = g.debugName + "-" + debugName
}
// Walk the graph.
var walkFn dag.WalkFunc
walkFn = func(v dag.Vertex) (diags tfdiags.Diagnostics) {
log.Printf("[TRACE] vertex %q: starting visit (%T)", dag.VertexName(v), v)
g.DebugVisitInfo(v, g.debugName)
defer func() {
log.Printf("[TRACE] vertex %q: visit complete", dag.VertexName(v))
}()
walker.EnterVertex(v)
defer walker.ExitVertex(v, diags)
// 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(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("%q (%T): nil eval tree", dag.VertexName(v), v))
}
// Allow the walker to change our tree if needed. Eval,
// then callback with the output.
log.Printf("[TRACE] vertex %q: evaluating", dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("evaluating %T(%s)", v, path))
tree = walker.EnterEvalTree(v, tree)
output, err := Eval(tree, vertexCtx)
diags = diags.Append(walker.ExitEvalTree(v, output, err))
if diags.HasErrors() {
return
}
}
// If the node is dynamically expanded, then expand it
if ev, ok := v.(GraphNodeDynamicExpandable); ok {
log.Printf("[TRACE] vertex %q: expanding dynamic subgraph", dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("expanding %T(%s)", v, path))
g, err := ev.DynamicExpand(vertexCtx)
if err != nil {
diags = diags.Append(err)
return
}
if g != nil {
// Walk the subgraph
log.Printf("[TRACE] vertex %q: entering dynamic subgraph", dag.VertexName(v))
subDiags := g.walk(walker)
diags = diags.Append(subDiags)
if subDiags.HasErrors() {
log.Printf("[TRACE] vertex %q: dynamic subgraph encountered errors", dag.VertexName(v))
return
}
log.Printf("[TRACE] vertex %q: dynamic subgraph completed successfully", dag.VertexName(v))
} else {
log.Printf("[TRACE] vertex %q: produced no dynamic subgraph", dag.VertexName(v))
}
}
// If the node has a subgraph, then walk the subgraph
if sn, ok := v.(GraphNodeSubgraph); ok {
log.Printf("[TRACE] vertex %q: entering static subgraph", dag.VertexName(v))
g.DebugVertexInfo(v, fmt.Sprintf("subgraph: %T(%s)", v, path))
subDiags := sn.Subgraph().(*Graph).walk(walker)
if subDiags.HasErrors() {
log.Printf("[TRACE] vertex %q: static subgraph encountered errors", dag.VertexName(v))
return
}
log.Printf("[TRACE] vertex %q: static subgraph completed successfully", dag.VertexName(v))
}
return
}
return g.AcyclicGraph.Walk(walkFn)
}