terraform/terraform/graph.go

97 lines
2.7 KiB
Go

package terraform
import (
"log"
"strings"
"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
}
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.EvalContext()
// Walk the graph.
walkFn := func(v dag.Vertex) (diags tfdiags.Diagnostics) {
log.Printf("[TRACE] vertex %q: starting visit (%T)", dag.VertexName(v), v)
defer func() {
log.Printf("[TRACE] vertex %q: visit complete", dag.VertexName(v))
}()
// vertexCtx is the context that we use when evaluating. This
// is normally the context of our graph but can be overridden
// with a GraphNodeModuleInstance impl.
vertexCtx := ctx
if pn, ok := v.(GraphNodeModuleInstance); ok {
vertexCtx = walker.EnterPath(pn.Path())
defer walker.ExitPath(pn.Path())
}
// If the node is exec-able, then execute it.
if ev, ok := v.(GraphNodeExecutable); ok {
diags = diags.Append(walker.Execute(vertexCtx, ev))
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, 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() {
var errs []string
for _, d := range subDiags {
errs = append(errs, d.Description().Summary)
}
log.Printf("[TRACE] vertex %q: dynamic subgraph encountered errors: %s", dag.VertexName(v), strings.Join(errs, ","))
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))
}
}
return
}
return g.AcyclicGraph.Walk(walkFn)
}