Install the GitHub App

Visit the Zerobillbot GitHub App page and click "Install". Choose your organization or personal account, then select which repositories to enable.

Your first cost analysis

Once installed, Zerobillbot automatically monitors pull requests for infrastructure-as-code changes. Open a PR that adds, modifies, or removes Terraform (.tf), CloudFormation, ARM templates, or Deployment Manager files.

Zerobillbot will:

1. Detect IaC resource changes in the diff
2. Look up current cloud pricing for each resource (AWS, Azure, GCP)
3. Post a cost impact comment with a detailed breakdown table
4. Create a GitHub Check Run (pass/warn/fail based on thresholds)

No config required

Zerobillbot works out of the box with sensible defaults. However, you can customize behavior by adding a .costbot.yml file to your repository root.

Create a .costbot.yml file in your repository root to customize Zerobillbot's behavior. All fields are optional.

# Cost thresholds (in USD per month)
thresholds:
  warn: 10      # Post a warning if cost delta exceeds this
  fail: 25      # Block the PR if cost delta exceeds this

# Resources to ignore (glob patterns)
ignore:
  - "aws_cloudwatch_log_group.*"
  - "aws_iam_*"
  - "aws_s3_bucket_policy.*"

# Notification settings (Pro plan)
notifications:
  slack:
    webhook: "https://hooks.slack.com/services/..."
    channel: "#infra-costs"
    on: ["warn", "fail"]
  teams:
    webhook: "https://outlook.office.com/webhook/..."
    on: ["fail"]

# Regions to use for pricing lookup
regions:
  - us-east-1
  - ap-southeast-1

# Comment settings
comment:
  collapse_unchanged: true    # Collapse resources with no cost change
  show_total: true            # Show total monthly estimate
  currency: "USD"             # Currency for display

Configuration options

Zerobillbot supports benchmarked pricing analysis across AWS, Azure, and GCP resource families.

AWS

• aws_instance — EC2 instances (all instance types)
• aws_ebs_volume — EBS volumes (gp2, gp3, io1, io2, st1, sc1)
• aws_nat_gateway — NAT Gateways
• aws_db_instance — RDS instances

Azure

• azurerm_linux_virtual_machine / azurerm_windows_virtual_machine
• azurerm_managed_disk, azurerm_sql_database, azurerm_kubernetes_cluster
• azurerm_public_ip, azurerm_nat_gateway, azurerm_lb

GCP

• google_compute_instance, google_compute_disk, google_compute_address
• google_sql_database_instance, google_container_cluster
• google_storage_bucket, google_cloud_run_service

Template support

For CloudFormation templates, Zerobillbot maps AWS::EC2::Instance, AWS::RDS::DBInstance, AWS::ECS::Service, and other resource types to equivalent pricing models. ARM and Deployment Manager templates are parsed with the same benchmark workflow used for Terraform-based changes.

Thresholds control how Zerobillbot responds to cost changes in your pull requests.

How thresholds work

Zerobillbot calculates the total estimated monthly cost delta for all infrastructure changes in a PR. This delta is compared against your configured thresholds:

• Below warn threshold: ✅ Check passes. Comment posted with cost breakdown.
• Between warn and fail: ⚠️ Check passes with a warning. Comment highlights the cost increase.
• Above fail threshold: ❌ Check fails. PR is blocked from merging (if branch protection is enabled).

Setting thresholds

Add thresholds to your .costbot.yml:

thresholds:
  warn: 10    # Warn if monthly delta > $10
  fail: 25    # Fail if monthly delta > $25

Recommended thresholds by team size