Terraform Dev

Terraform Development Loop

Fast feedback during active Terraform development using Makefile targets.

Plan caching

Always capture plan output to a temp file. Plans are expensive (network, credentials, time). Cache once, grep/parse many times.

PLAN_DIR=$(mktemp -d)
terraform plan -no-color 2>&1 | tee "$PLAN_DIR/plan.txt"
echo "Plan cached: $PLAN_DIR/plan.txt"

Then use the cached file for all post-hoc analysis:

# Quick summary
grep '^Plan:' "$PLAN_DIR/plan.txt"

# Find destroys
grep 'will be destroyed' "$PLAN_DIR/plan.txt"

# Non-tag attribute changes
grep -E '^\s+[~+-].*=' "$PLAN_DIR/plan.txt" | grep -v 'tags'

# Feed to plan parser for structured analysis
# See terraform-plan-parser skill

For multi-env work, namespace per env:

PLAN_DIR=$(mktemp -d)
for env in dev tst prd; do
  (cd iac/$env && terraform plan -no-color 2>&1 | tee "$PLAN_DIR/${env}-plan.txt")
done
echo "Plans cached in: $PLAN_DIR"

Prerequisites

• make — drives all targets below
• terraform — for format, validate, and plan
• tflint — for lint targets
• entr or watchexec — optional, for file-watch mode (see Watching for Changes)

Inner Loop (Fast — < 30s)

Run after every meaningful code change:

make format          # terraform fmt -recursive (~1s)
make validate        # terraform validate (~2s)
make lint            # tflint (~5s)

Compose for a single fast-fail check:

make format && make validate && make lint

What each catches:

• make format — inconsistent indentation, alignment
• make validate — type errors, undefined references, malformed HCL
• make lint — security defaults too open, missing types, lookup() usage, line length

Outer Loop (Full — 2–5 min)

Run before pushing or opening a PR:

make pre-pr          # format + validate-full + lint + docs + examples

Example Testing Loop

When changing module interface (variables, outputs, resources):

# Convert to local source for testing
make relative-source

# Test all examples against local code
make test-examples

# Revert to registry source before committing
make registry-source

TFC Deployment Loop

For real-world validation against a live AWS account:

# Deploy example to test workspace
make deploy EXAMPLE=basic WORKSPACE=<tec-dce-inn-dev-XXXXX-username>

# Monitor run
make tfc-run-status EXAMPLE=basic

# Inspect deployed resources (tags, names, outputs)
make tfc-workspace-state EXAMPLE=basic

# Tear down
make deploy-clean EXAMPLE=basic

Safe Experimentation

Before risky refactors:

make checkpoint MSG="before restructuring locals"
# ... make changes ...
# If it goes wrong: git reset --soft HEAD~1

Watching for Changes

For continuous validation while editing multiple files:

# Run inner loop on every save (requires entr or watchexec)
find . -name "*.tf" | entr -c make format validate lint

# Or use terraform-docs watcher if available

Common Failures and Fixes

References

• tfc-api skill — direct TFC API queries for deeper workspace inspection
• terraform-plan-parser skill — structured analysis of terraform plan output for import validation and drift detection

Source: shalomb/agent-skills — distributed by TomeVault.