terraform/internal/terraform/context_eval.go

105 lines
3.9 KiB
Go

package terraform
import (
"log"
"github.com/hashicorp/terraform/internal/addrs"
"github.com/hashicorp/terraform/internal/configs"
"github.com/hashicorp/terraform/internal/lang"
"github.com/hashicorp/terraform/internal/states"
"github.com/hashicorp/terraform/internal/tfdiags"
)
type EvalOpts struct {
SetVariables InputValues
}
// Eval produces a scope in which expressions can be evaluated for
// the given module path.
//
// This method must first evaluate any ephemeral values (input variables, local
// values, and output values) in the configuration. These ephemeral values are
// not included in the persisted state, so they must be re-computed using other
// values in the state before they can be properly evaluated. The updated
// values are retained in the main state associated with the receiving context.
//
// This function takes no action against remote APIs but it does need access
// to all provider and provisioner instances in order to obtain their schemas
// for type checking.
//
// The result is an evaluation scope that can be used to resolve references
// against the root module. If the returned diagnostics contains errors then
// the returned scope may be nil. If it is not nil then it may still be used
// to attempt expression evaluation or other analysis, but some expressions
// may not behave as expected.
func (c *Context) Eval(config *configs.Config, state *states.State, moduleAddr addrs.ModuleInstance, opts *EvalOpts) (*lang.Scope, tfdiags.Diagnostics) {
// This is intended for external callers such as the "terraform console"
// command. Internally, we create an evaluator in c.walk before walking
// the graph, and create scopes in ContextGraphWalker.
var diags tfdiags.Diagnostics
defer c.acquireRun("eval")()
schemas, moreDiags := c.Schemas(config, state)
diags = diags.Append(moreDiags)
if moreDiags.HasErrors() {
return nil, diags
}
// Start with a copy of state so that we don't affect the instance that
// the caller is holding.
state = state.DeepCopy()
var walker *ContextGraphWalker
variables := mergeDefaultInputVariableValues(opts.SetVariables, config.Module.Variables)
// By the time we get here, we should have values defined for all of
// the root module variables, even if some of them are "unknown". It's the
// caller's responsibility to have already handled the decoding of these
// from the various ways the CLI allows them to be set and to produce
// user-friendly error messages if they are not all present, and so
// the error message from checkInputVariables should never be seen and
// includes language asking the user to report a bug.
varDiags := checkInputVariables(config.Module.Variables, variables)
diags = diags.Append(varDiags)
log.Printf("[DEBUG] Building and walking 'eval' graph")
graph, moreDiags := (&EvalGraphBuilder{
Config: config,
State: state,
Components: c.components,
Schemas: schemas,
}).Build(addrs.RootModuleInstance)
diags = diags.Append(moreDiags)
if moreDiags.HasErrors() {
return nil, diags
}
walkOpts := &graphWalkOpts{
InputState: state,
Config: config,
Schemas: schemas,
RootVariableValues: variables,
}
walker, moreDiags = c.walk(graph, walkEval, walkOpts)
diags = diags.Append(moreDiags)
if walker != nil {
diags = diags.Append(walker.NonFatalDiagnostics)
} else {
// If we skipped walking the graph (due to errors) then we'll just
// use a placeholder graph walker here, which'll refer to the
// unmodified state.
walker = c.graphWalker(walkEval, walkOpts)
}
// This is a bit weird since we don't normally evaluate outside of
// the context of a walk, but we'll "re-enter" our desired path here
// just to get hold of an EvalContext for it. ContextGraphWalker
// caches its contexts, so we should get hold of the context that was
// previously used for evaluation here, unless we skipped walking.
evalCtx := walker.EnterPath(moduleAddr)
return evalCtx.EvaluationScope(nil, EvalDataForNoInstanceKey), diags
}