// Graph builds a dependency graph of all the resources for infrastructure
// change.
//
// This dependency graph shows the correct order that any resources need
// to be operated on.
//
// The Meta field of a graph Noun can contain one of the follow types. A
// description is next to each type to explain what it is.
//
// *GraphNodeResource - A resource. See the documentation of this
// struct for more details.
// *GraphNodeResourceProvider - A resource provider that needs to be
// configured at this point.
//
func Graph(opts *GraphOpts) (*depgraph.Graph, error) {
if opts.Config == nil {
return nil, errors.New("Config is required for Graph")
}
log.Printf("[DEBUG] Creating graph...")
g := new(depgraph.Graph)
// First, build the initial resource graph. This only has the resources
// and no dependencies.
graphAddConfigResources(g, opts.Config, opts.State)
// Add explicit dependsOn dependencies to the graph
graphAddExplicitDeps(g)
// Next, add the state orphans if we have any
if opts.State != nil {
graphAddOrphans(g, opts.Config, opts.State)
}
// Map the provider configurations to all of the resources
graphAddProviderConfigs(g, opts.Config)
// Setup the provisioners. These may have variable dependencies,
// and must be done before dependency setup
if err := graphMapResourceProvisioners(g, opts.Provisioners); err != nil {
return nil, err
}
// Add all the variable dependencies
graphAddVariableDeps(g)
// Build the root so that we have a single valid root
graphAddRoot(g)
// If providers were given, lets associate the proper providers and
// instantiate them.
if len(opts.Providers) > 0 {
// Add missing providers from the mapping
if err := graphAddMissingResourceProviders(g, opts.Providers); err != nil {
return nil, err
}
// Initialize all the providers
if err := graphInitResourceProviders(g, opts.Providers); err != nil {
return nil, err
}
// Map the providers to resources
if err := graphMapResourceProviders(g); err != nil {
return nil, err
}
}
// If we have a diff, then make sure to add that in
if opts.Diff != nil {
if err := graphAddDiff(g, opts.Diff); err != nil {
return nil, err
}
}
// Validate
if err := g.Validate(); err != nil {
return nil, err
}
log.Printf(
"[DEBUG] Graph created and valid. %d nouns.",
len(g.Nouns))
return g, nil
}
