rshade Cost Check
Detect the IaC stack in the current directory, run a compatible cost tool, and produce a cost report with flagged items.
Core principle: Orchestrate real cost tools — do not parse IaC files directly or estimate prices manually.
Step 1: Detect IaC stack
Scan the current directory for IaC project files:
ls Pulumi.yaml 2>/dev/null && echo "pulumi: detected"
ls *.tf 2>/dev/null && echo "terraform: detected"
If no IaC files are found, stop and report: "No IaC project detected in this directory."
For the full detection table, see references/tool-matrix.md.
Step 2: Detect cost tool
For each detected IaC stack, check if a compatible cost tool is installed:
command -v finfocus 2>/dev/null && echo "finfocus: available"
command -v infracost 2>/dev/null && echo "infracost: available"
If no compatible tool is found for a detected stack, soft-fail:
report which IaC stack was detected and recommend the appropriate
tool. Do not prescribe install commands — link to the tool's own
documentation. See references/tool-matrix.md for recommendations.
If the only available tool is incompatible with the detected stack (e.g., infracost found but project is Pulumi), treat the same as no tool found.
Step 3: Load thresholds
Check for .cost-check.yml in the project root. If present, read
threshold overrides. If absent, use defaults from
references/default-thresholds.md:
- resource: $100/mo (flag individual resources above)
- increase: $50/mo (flag cost increases above)
- increase_pct: 20% (flag cost increase percentage above)
- total: $1000/mo (flag total cost above)
Step 4: Read baseline
If a previous COST_CHECK.md exists in the project root, read the
total monthly cost from it. This serves as the baseline for delta
comparison. If no previous report exists, skip delta flagging.
Step 5: Run cost tool
Run the compatible cost tool for each detected IaC stack. See
references/tool-parsers.md for per-tool invocation and parsing
instructions.
Capture the full output. Extract into the normalized structure:
- Total projected monthly cost
- Per-stack/workspace breakdown
- Per-resource-type grouping within each stack
- Individual resource costs
Step 6: Flag items
Apply thresholds to the normalized cost data:
- Expensive resources — flag any resource with monthly cost above the resource threshold
- Cost increase — if a baseline exists, flag if the total cost increase exceeds the increase threshold OR the increase percentage exceeds the increase_pct threshold
- Total cost — flag if total projected cost across all stacks exceeds the total threshold
Step 7: Terminal summary
Print the results immediately:
- IaC stack and cost tool used
- Per-stack total with resource type breakdown
- Flagged items with threshold that triggered the flag
- Delta from baseline (if baseline exists)
- Total across all stacks
Step 8: Generate COST_CHECK.md
Write the report to the project root using the template in
references/report-template.md. Include all sections: summary,
stack breakdown, flagged items, thresholds used, and tool info.
Run markdownlint on the generated file.
Step 9: Present results
Show the user:
- Total projected cost across all stacks
- Number of flagged items by category
- Top flagged items with costs
- Delta from previous check (if baseline existed)
- Ask if they want to adjust thresholds or investigate specific items