Terraform Internals and Provider Development

Build a pinned Terraform source revision and run one targeted Core test.

Classify the responsibilities of Terraform Core, HCL, cty, go-plugin, Terraform's plugin libraries, and provider repositories.

Use Go package metadata and `go list` to identify an internal package's direct dependency boundaries.

Locate the CLI command-dispatch path for a `terraform plan` invocation.

Trace a `plan` invocation from CLI argument handling to backend operation creation.

Diagram the data exchanged among configuration loading, Core, state storage, and provider processes.

Correlate a `TF_LOG=TRACE` message with the source function that emitted it.

Use Delve to stop at and inspect one selected Terraform CLI execution path.

Parse a Terraform configuration with `hclsyntax` and inspect its syntax tree.

Extract attributes and nested blocks from an HCL body using a body schema.

Use HCL source ranges to produce a diagnostic tied to the offending configuration text.

Demonstrate the boundary between parsing an expression and evaluating it.

Determine which configuration files Terraform loads from a working directory and how it combines their bodies.

Define clone-side configuration types for `terraform`, `variable`, `locals`, `provider`, and managed-resource blocks.

Implement a directory loader that returns clone configuration objects and HCL diagnostics.

Write table-driven loader tests for malformed, duplicate, and deliberately unsupported configuration constructs.

Construct and inspect primitive, collection, tuple, and object values with cty.

Distinguish null, unknown, and dynamically typed cty values in evaluation results.

Build an HCL evaluation context that resolves input-variable traversals.

Evaluate input-variable defaults and convert supplied values to declared types.

Evaluate local values in dependency order and report a local-value cycle.

Evaluate managed-resource arguments using variables, locals, a small pure-function set, and supplied values for referenced resource instances.

Preserve a sensitive-value mark while transforming a cty value.

Test null and unknown propagation through representative expressions.

Parse absolute managed-resource addresses that include keyed instances.

Distinguish configuration-resource, resource-instance, and module-instance addresses in Terraform Core.

Extract a referenced resource address from an HCL traversal while preserving its remaining attribute path.

Define a clone provider-schema model with required, optional, and computed attributes.

Validate a managed-resource configuration against the clone provider-schema model.

Resolve a managed resource to its default or aliased provider configuration.

Expand a managed resource using `count` into stable integer-keyed instances.

Expand a managed resource using `for_each` into stable string-keyed instances.

Trace one Terraform graph-transformation pipeline and explain why Core constructs graphs through staged transformations.

Represent resource instances, provider configurations, and operation roots as typed graph nodes.

Add implicit dependency edges by extracting references from parsed configuration expressions.

Add explicit dependency edges for `depends_on` without duplicating implicit edges.

Add provider-initialization edges to every resource instance that uses that provider.

Detect a dependency cycle and report the addresses participating in it.

Compute deterministic topological execution layers for an acyclic clone graph.

Render the clone graph as DOT and verify its nodes and edges against a test fixture.

Map a Terraform state snapshot to its hierarchy of modules, resources, instances, and instance-object generations.

Distinguish ready, tainted, and deposed resource instance objects.

Implement address-based lookup, insertion, replacement, and removal in an in-memory clone state.

Serialize clone state with cty type and sensitive-path metadata while rejecting unknown values at persistence time.

Enforce state lineage and monotonically increasing serial numbers when saving state.

Write local state atomically while retaining a recoverable backup.

Implement an exclusive local-state lock with ownership metadata.

Diagnose an address or lineage mismatch from a state snapshot and prepare a safe recovery procedure.

Distinguish init-time provider version selection and checksum verification from runtime provider-executable discovery.

Explain the process handshake and protocol-version negotiation between Terraform and a provider.

Identify the protocol requests used for schema retrieval, configuration validation, planning, reading, and applying resources.

Encode and decode a representative cty value as a protocol dynamic value.

Define the reduced provider interface required by the educational clone.

Implement an in-memory mock provider with schema, validation, read, plan, and apply behavior.

Run the mock provider as a separate process behind a small clone-specific educational RPC boundary.

Propagate provider diagnostics, cancellation, and process failure back to the clone operation.

Trace the major source-level stages of a Terraform planning operation.

Refresh a prior resource instance by calling the clone provider's read operation.

Construct a proposed resource value from configuration, prior state, and provider schema.

Implement a recursive typed diff that preserves attribute paths.

Classify a resource-instance change as no-op, create, update, or delete.

Mark a planned change as replacement when an immutable attribute changes.

Propagate unknown computed attributes through a planned resource value.

Serialize a saved plan with configuration, provider, state-lineage, and state-serial checks.

Trace the Terraform source path that constructs and walks an apply graph, identifying its operation, failure, and replacement nodes.

Transform planned resource changes into a clone apply dependency graph.

Schedule independent apply nodes with a configurable concurrency bound.

Send planned changes to the provider and commit returned state while preserving successful commits if another node fails.

Prevent dependent nodes from running after one of their prerequisites fails.

Execute destroy-before-create replacement in dependency-safe order.

Execute create-before-destroy replacement using a deposed prior object.

Cancel an in-progress graph walk cleanly after an interrupt signal.

Assemble configuration, provider, graph, state, plan, and apply services behind an operation context.

Implement a `validate` command that reports configuration and provider-schema diagnostics.

Implement a `plan` command that writes both human-readable output and a saved plan.

Implement an `apply` command that rejects a stale or foreign saved plan.

Load an explicitly configured clone-compatible provider executable for a clone run.

Run an end-to-end create, update, drift, replacement, and destroy test with the mock provider.

Diagnose an unexpected plan by correlating graph, refresh, diff, and provider logs.

Diagnose a state-related apply failure without manually editing the only state copy.

At a pinned AWS provider revision, map the responsibilities and boundaries of terraform-plugin-sdk/v2, the Plugin Framework, and provider multiplexing.

Trace provider startup from the AWS provider server entry point to registration of the `aws_s3_bucket` resource.

Trace provider configuration from Terraform input to construction of an authenticated AWS client.

Interpret required, optional, computed, replacement, and validation behavior in the `aws_s3_bucket` schema.

Trace the resource's create path from a protocol request to AWS API calls and returned state.

Trace the resource's read path through drift detection, not-found handling, and state reconciliation.

Trace the resource's delete path through dependency cleanup, retries, and completion waiting.

Trace a tag-only update and identify the shared helpers used for tagging, error classification, retries, and timeouts.

Scaffold a Plugin Framework provider and use debug logs to demonstrate its provider and resource lifecycle callbacks under the real Terraform CLI.

Configure an AWS SDK client with region selection, credential-chain support, and an allowed-account check.

Define a focused S3 bucket model and schema with a required bucket name, optional tags, computed identifiers, replacement behavior, and import by bucket name.

Implement bucket creation with region-correct request behavior and Framework diagnostic handling.

Implement bucket reading that reconciles drift and removes an externally deleted bucket from Terraform state.

Implement tag updates without recreating the S3 bucket.

Implement idempotent bucket deletion with bounded waiting and not-found handling.

Run an environment-gated, cost-safe acceptance lifecycle covering create, import, out-of-band tag drift, update, and destroy with reliable cleanup.