opentofu/terraform/graph.go
James Bardin 0b025d74e5 add EvalContext.WithPath
As the Graph is walked, the current way to set the context path was to
have the walker return a context from EnterPath. This required that
every node know it's absolute path, which can no longer be the case
during plan when modules have not been expanded.

This introduces a new method called WithPath, which returns a copy of
the context with the internal path updated to reflect the method
argument. Any use of the EvalContext that requires knowing the path will
now panic if it wasn't explicitly set to ensure that evaluations always
occur in the correct path.

Add EvalContext to the GraphWalker interface.
EvalContext returns an EvalContext that has not yet set a path. This
will allow us to enforce that all context operations requiring a module
instance path will require that a path be explicitly set rather than
evaluating within the wrong path.
2020-03-25 17:03:06 -04:00

108 lines
3.0 KiB
Go

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
}
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.
var walkFn dag.WalkFunc
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))
}()
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 GraphNodeModuleInstance impl.
vertexCtx := ctx
if pn, ok := v.(GraphNodeModuleInstance); ok {
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))
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, 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))
}
}
return
}
return g.AcyclicGraph.Walk(walkFn)
}