$ TF_LOG=trace terraform apply
2020/02/18 21:36:20 [INFO] Terraform version: 0.12.20  
2020/02/18 21:36:20 [INFO] Go runtime version: go1.13.6
2020/02/18 21:36:20 [INFO] CLI args: []string{"/usr/bin/terraform", "apply"}
2020/02/18 21:36:20 [DEBUG] Attempting to open CLI config file: /home/mike/.terraformrc
2020/02/18 21:36:20 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2020/02/18 21:36:20 [DEBUG] checking for credentials in "/home/mike/.terraform.d/plugins"
2020/02/18 21:36:20 [INFO] CLI command args: []string{"apply"}
2020/02/18 21:36:20 [TRACE] Meta.Backend: no config given or present on disk, so returning nil config
2020/02/18 21:36:20 [TRACE] Meta.Backend: backend has not previously been initialized in this working directory
2020/02/18 21:36:20 [DEBUG] New state was assigned lineage "5921fd19-72a6-b4a1-e1fd-ba47163b7578"
2020/02/18 21:36:20 [TRACE] Meta.Backend: using default local state only (no backend configuration, and no existing initialized backend)
2020/02/18 21:36:20 [TRACE] Meta.Backend: instantiated backend of type <nil>
2020/02/18 21:36:20 [DEBUG] checking for provider in "."
2020/02/18 21:36:20 [DEBUG] checking for provider in "/usr/bin"
2020/02/18 21:36:20 [DEBUG] checking for provider in "/home/mike/.terraform.d/plugins"
2020/02/18 21:36:20 [DEBUG] checking for provisioner in "."
2020/02/18 21:36:20 [DEBUG] checking for provisioner in "/usr/bin"
2020/02/18 21:36:20 [DEBUG] checking for provisioner in "/home/mike/.terraform.d/plugins"
2020/02/18 21:36:20 [INFO] Failed to read plugin lock file .terraform/plugins/linux_amd64/lock.json: open .terraform/plugins/linux_amd64/lock.json: no such file or directory
2020/02/18 21:36:20 [TRACE] Meta.Backend: backend <nil> does not support operations, so wrapping it in a local backend
2020/02/18 21:36:20 [INFO] backend/local: starting Apply operation
2020/02/18 21:36:20 [TRACE] backend/local: requesting state manager for workspace "default"
2020/02/18 21:36:20 [TRACE] backend/local: state manager for workspace "default" will:
 - read initial snapshot from terraform.tfstate
 - write new snapshots to terraform.tfstate
 - create any backup at terraform.tfstate.backup
2020/02/18 21:36:20 [TRACE] backend/local: requesting state lock for workspace "default"
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: preparing to manage state snapshots at terraform.tfstate
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: no previously-stored snapshot exists
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: locking terraform.tfstate using fcntl flock
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: writing lock metadata to .terraform.tfstate.lock.info
2020/02/18 21:36:20 [TRACE] backend/local: reading remote state for workspace "default"
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: reading latest snapshot from terraform.tfstate
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: snapshot file has nil snapshot, but that's okay
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: read nil snapshot
2020/02/18 21:36:20 [TRACE] backend/local: retrieving local state snapshot for workspace "default"
2020/02/18 21:36:20 [TRACE] backend/local: building context for current working directory
2020/02/18 21:36:20 [TRACE] terraform.NewContext: starting
2020/02/18 21:36:20 [TRACE] terraform.NewContext: resolving provider version selections
2020/02/18 21:36:20 [TRACE] terraform.NewContext: loading provider schemas
2020/02/18 21:36:20 [TRACE] terraform.NewContext: complete
2020/02/18 21:36:20 [TRACE] backend/local: finished building terraform.Context
2020/02/18 21:36:20 [TRACE] backend/local: requesting interactive input, if necessary
2020/02/18 21:36:20 [TRACE] Context.Input: Prompting for provider arguments
2020/02/18 21:36:20 [TRACE] backend/local: running validation operation
2020/02/18 21:36:20 [INFO] terraform: building graph: GraphTypeValidate
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ConfigTransformer
2020/02/18 21:36:20 [TRACE] ConfigTransformer: Starting for path: 
2020/02/18 21:36:20 [TRACE] ConfigTransformer: Starting for path: mod1
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ConfigTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.LocalTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.LocalTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.OutputTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.OutputTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.OrphanResourceInstanceTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.OrphanResourceInstanceTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.StateTransformer
2020/02/18 21:36:20 [TRACE] StateTransformer: state is empty, so nothing to do
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.StateTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.OrphanOutputTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.OrphanOutputTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachResourceConfigTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachResourceConfigTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachStateTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachStateTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.RootVariableTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.RootVariableTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.MissingProvisionerTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.MissingProvisionerTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ProvisionerTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ProvisionerTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ModuleVariableTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ModuleVariableTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.graphTransformerMulti
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ProviderConfigTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ProviderConfigTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.MissingProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.MissingProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.PruneProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.PruneProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ParentProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ParentProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.graphTransformerMulti (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.RemovedModuleTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.RemovedModuleTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachSchemaTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachSchemaTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ReferenceTransformer
2020/02/18 21:36:20 [DEBUG] ReferenceTransformer: "module.mod1.output.foo" references: [module.mod1.var.optional_input]
2020/02/18 21:36:20 [DEBUG] ReferenceTransformer: "module.mod1.var.optional_input" references: []
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ReferenceTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
    module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.CountBoundaryTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.CountBoundaryTransformer with new graph:
  meta.count-boundary (EachMode fixup) - *terraform.NodeCountBoundary
    module.mod1.output.foo - *terraform.NodeApplyableOutput
    module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  module.mod1.output.foo - *terraform.NodeApplyableOutput
    module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.TargetsTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.TargetsTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ForcedCBDTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ForcedCBDTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.CloseProviderTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.CloseProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.CloseProvisionerTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.CloseProvisionerTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.RootTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.RootTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.TransitiveReductionTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.TransitiveReductionTransformer with new graph:
  meta.count-boundary (EachMode fixup) - *terraform.NodeCountBoundary
    module.mod1.output.foo - *terraform.NodeApplyableOutput
  module.mod1.output.foo - *terraform.NodeApplyableOutput
    module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [DEBUG] Starting graph walk: walkValidate
2020/02/18 21:36:20 [TRACE] dag/walk: updating graph
2020/02/18 21:36:20 [TRACE] dag/walk: added new vertex: "module.mod1.output.foo"
2020/02/18 21:36:20 [TRACE] dag/walk: added new vertex: "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] dag/walk: added new vertex: "meta.count-boundary (EachMode fixup)"
2020/02/18 21:36:20 [TRACE] dag/walk: added edge: "module.mod1.output.foo" waiting on "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] dag/walk: added edge: "meta.count-boundary (EachMode fixup)" waiting on "module.mod1.output.foo"
2020/02/18 21:36:20 [TRACE] dag/walk: dependencies changed for "module.mod1.output.foo", sending new deps
2020/02/18 21:36:20 [TRACE] dag/walk: dependencies changed for "meta.count-boundary (EachMode fixup)", sending new deps
2020/02/18 21:36:20 [TRACE] dag/walk: visiting "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": starting visit (*terraform.NodeApplyableModuleVariable)
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": evaluating
2020/02/18 21:36:20 [TRACE] [walkValidate] Entering eval tree: module.mod1.var.optional_input
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalSequence
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalOpFilter
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalModuleCallArgument
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalSetModuleCallArguments
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.evalVariableValidations
2020/02/18 21:36:20 [TRACE] evalVariableValidations: not active for module.mod1.var.optional_input, so skipping
2020/02/18 21:36:20 [TRACE] [walkValidate] Exiting eval tree: module.mod1.var.optional_input
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": visit complete
2020/02/18 21:36:20 [TRACE] dag/walk: visiting "module.mod1.output.foo"
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": starting visit (*terraform.NodeApplyableOutput)
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": evaluating
2020/02/18 21:36:20 [TRACE] [walkValidate] Entering eval tree: module.mod1.output.foo
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalSequence
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalOpFilter
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalWriteOutput
2020/02/18 21:36:20 [TRACE] EvalWriteOutput: Removing module.mod1.output.foo from state (it is now null)
2020/02/18 21:36:20 [TRACE] EvalWriteOutput: Saving Create change for module.mod1.output.foo in changeset
2020/02/18 21:36:20 [TRACE] [walkValidate] Exiting eval tree: module.mod1.output.foo
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": visit complete
2020/02/18 21:36:20 [TRACE] dag/walk: visiting "meta.count-boundary (EachMode fixup)"
2020/02/18 21:36:20 [TRACE] vertex "meta.count-boundary (EachMode fixup)": starting visit (*terraform.NodeCountBoundary)
2020/02/18 21:36:20 [TRACE] vertex "meta.count-boundary (EachMode fixup)": evaluating
2020/02/18 21:36:20 [TRACE] [walkValidate] Entering eval tree: meta.count-boundary (EachMode fixup)
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalCountFixZeroOneBoundaryGlobal
2020/02/18 21:36:20 [TRACE] [walkValidate] Exiting eval tree: meta.count-boundary (EachMode fixup)
2020/02/18 21:36:20 [TRACE] vertex "meta.count-boundary (EachMode fixup)": visit complete
2020/02/18 21:36:20 [INFO] backend/local: apply calling Refresh
2020/02/18 21:36:20 [INFO] terraform: building graph: GraphTypeRefresh
2020/02/18 21:36:20 [TRACE] No managed resources in state during refresh; skipping managed resource transformer
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ConfigTransformer
2020/02/18 21:36:20 [TRACE] ConfigTransformer: Starting for path: 
2020/02/18 21:36:20 [TRACE] ConfigTransformer: Starting for path: mod1
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ConfigTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.OrphanResourceInstanceTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.OrphanResourceInstanceTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.StateTransformer
2020/02/18 21:36:20 [TRACE] StateTransformer: state is empty, so nothing to do
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.StateTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachStateTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachStateTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachResourceConfigTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachResourceConfigTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.RootVariableTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.RootVariableTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.LocalTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.LocalTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.OutputTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.OutputTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ModuleVariableTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ModuleVariableTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.graphTransformerMulti
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ProviderConfigTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ProviderConfigTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.MissingProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.MissingProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.PruneProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.PruneProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Executing graph transform *terraform.ParentProviderTransformer
2020/02/18 21:36:20 [TRACE] (graphTransformerMulti) Completed graph transform *terraform.ParentProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.graphTransformerMulti (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachSchemaTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachSchemaTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.ReferenceTransformer
2020/02/18 21:36:20 [DEBUG] ReferenceTransformer: "module.mod1.output.foo" references: [module.mod1.var.optional_input]
2020/02/18 21:36:20 [DEBUG] ReferenceTransformer: "module.mod1.var.optional_input" references: []
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.ReferenceTransformer with new graph:
  module.mod1.output.foo - *terraform.NodeApplyableOutput
    module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  module.mod1.var.optional_input - *terraform.NodeApplyableModuleVariable
  ------
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.AttachDependenciesTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.AttachDependenciesTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.TargetsTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.TargetsTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.CloseProviderTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.CloseProviderTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.RootTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.RootTransformer (no changes)
2020/02/18 21:36:20 [TRACE] Executing graph transform *terraform.TransitiveReductionTransformer
2020/02/18 21:36:20 [TRACE] Completed graph transform *terraform.TransitiveReductionTransformer (no changes)
2020/02/18 21:36:20 [DEBUG] Starting graph walk: walkRefresh
2020/02/18 21:36:20 [TRACE] dag/walk: updating graph
2020/02/18 21:36:20 [TRACE] dag/walk: added new vertex: "module.mod1.output.foo"
2020/02/18 21:36:20 [TRACE] dag/walk: added new vertex: "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] dag/walk: added edge: "module.mod1.output.foo" waiting on "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] dag/walk: dependencies changed for "module.mod1.output.foo", sending new deps
2020/02/18 21:36:20 [TRACE] dag/walk: visiting "module.mod1.var.optional_input"
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": starting visit (*terraform.NodeApplyableModuleVariable)
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": evaluating
2020/02/18 21:36:20 [TRACE] [walkRefresh] Entering eval tree: module.mod1.var.optional_input
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalSequence
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalOpFilter
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalModuleCallArgument
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.EvalSetModuleCallArguments
2020/02/18 21:36:20 [TRACE] <root>: eval: *terraform.evalVariableValidations
2020/02/18 21:36:20 [TRACE] evalVariableValidations: not active for module.mod1.var.optional_input, so skipping
2020/02/18 21:36:20 [TRACE] [walkRefresh] Exiting eval tree: module.mod1.var.optional_input
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.var.optional_input": visit complete
2020/02/18 21:36:20 [TRACE] dag/walk: visiting "module.mod1.output.foo"
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": starting visit (*terraform.NodeApplyableOutput)
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": evaluating
2020/02/18 21:36:20 [TRACE] [walkRefresh] Entering eval tree: module.mod1.output.foo
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalSequence
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalOpFilter
2020/02/18 21:36:20 [TRACE] module.mod1: eval: *terraform.EvalWriteOutput
2020/02/18 21:36:20 [ERROR] module.mod1: eval: *terraform.EvalWriteOutput, err: Operation failed: Error during operation: argument must not be null.
2020/02/18 21:36:20 [ERROR] module.mod1: eval: *terraform.EvalOpFilter, err: Operation failed: Error during operation: argument must not be null.
2020/02/18 21:36:20 [ERROR] module.mod1: eval: *terraform.EvalSequence, err: Operation failed: Error during operation: argument must not be null.
2020/02/18 21:36:20 [TRACE] [walkRefresh] Exiting eval tree: module.mod1.output.foo
2020/02/18 21:36:20 [TRACE] vertex "module.mod1.output.foo": visit complete

2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: removing lock metadata file .terraform.tfstate.lock.info
Error: Operation failed
2020/02/18 21:36:20 [TRACE] statemgr.Filesystem: unlocking terraform.tfstate using fcntl flock

  on mod1/main.tf line 6, in output "foo":
   6:   value = var.optional_input / 5
    |----------------
    | var.optional_input is null

Error during operation: argument must not be null.