Introduction
Infracost is an open-source fin-ops tool that helps DevOps and developers continuously reduce their cloud costs.
Infracost integrates with terraform (Infrastructure-as-a-code tool) to provide the breakdown of cost and difference in cost for any pull request that DevOps/Developers raised with shift-left approach.
Infracost empowers to discuss costs before the actual resources are created, not after the resources are created.
Getting Started
Installation
1. Install Infracost
Assuming Terraform is already installed, get the latest Infracost release on mac:
brew install infracost
2. Get API key
Register for a free API key:
infracost register
The key is saved in ~/.config/infracost/credentials.yml .
3. Run it
Run Infracost using our example Terraform project to see how it works:
git clone git@github.com:org/terraform.git
cd kong-terraform
# Get breakdown of cost for one of the env
infracost breakdown –path /dev/
# Show diff of monthly costs, edit the yaml file and re-run to compare costs infracost diff –path /dev/ –usage-file /dev/infracost-usage.yml
Advanced usage
The following advanced usage methods can be used in addition to the usage methods mentioned above.
Using Terraform plan file
Infracost can be run against a Terraform plan file.
cd /dev/
terraform init
terraform plan -out tfplan.binary
infracost breakdown –path tfplan.binary
infracost diff –path tfplan.binary
Using Terraform state
The infracost breakdown command has a –terraform-use-state flag that is useful if you want to see the cost breakdown of the current Terraform state. This implies that you have already run Terraform apply .
infracost breakdown –path /dev/ –terraform-use-state
Using Terraform state JSON file
The infracost breakdown command can be run against a Terraform state JSON file. This implies that you have already run Terraform apply , thus no cloud creds or –terraform-plan-flags is needed.
cd /dev/
terraform show -json > tfstate.json
infracost breakdown –path tfstate.json
Generate reports
The infracost breakdown command has a –format json|table|html flag that can be used to change the output format. The JSON option can be used to generate files from individual projects that can then be consumed by the infracost output command to generate a combined report. The output command has a –format json|diff|table|html flag that sets the report format.
Usage
Run infracost output –help to see the available options. Example usage:
infracost breakdown –path /dev/ –format json > project1.json infracost breakdown –path /stage/ –format json > project2.json infracost output –path project*.json –format html > report.html
https://s3-us-west-2.amazonaws.com/secure.notion-static.com/94b48619-c82d-4a45-a9f4-350c0f59f1a0/report.html
Config file
An Infracost config file can be created in each of your Terraform project repos to specify how Infracost should be run.
1. Create an infracost.yml file in each of your Terraform project repos. Each project can have the parameters mentioned in the table below:
version: 0.1
projects:
– path: /dev/tfplan.json
usage_file:/dev/infracost-usage.yml
– path: /test/tfplan.json
usage_file: /test/infracost-usage.yml
2. Pass the file to the infracost breakdown or infracost diff using the -config-file option.
infracost breakdown –config-file infracost.yml
infracost diff –config-file infracost.yml
Usage-based resources
Infracost distinguishes the price of a resource from its cost. For example, an EC2 instance might be priced at $0.02 per hour, and if run for 100 hours (its usage), it’ll cost $2. Supported resources in Infracost will always show prices, but if a resource has a usage-based cost component, we can’t show its cost as we don’t know how much it’ll be used. For example, an AWS Lambda resource shows no monthly costs for requests and duration:
Name Quantity Unit Monthly Cost aws_lambda_function.hi
├─ Requests Cost depends on usage: $0.20 per 1M requests
└─ Duration Cost depends on usage: $0.0000166667 per GB-seconds
PROJECT TOTAL $0.00
Infracost usage file
Infracost solves the above problem by enabling you to describe usage estimates in a file called infracost-usage.yml , which can be passed to Infracost using the –usage-file option so it can calculate costs. An infracost-usage.yml file with Lambda function usage estimates:
version: 0.1
resource_usage:
aws_lambda_function.hi:
monthly_requests: 100000000 # Monthly requests to the Lambda function.
request_duration_ms: 250 # Average duration of each request in milliseconds.
Running infracost breakdown –config-file infracost.yml –usage-file=infracost-usage.yml now shows monthly cost estimates:
Name Quantity Unit Monthly Cost
aws_lambda_function.hi
├─ Requests 100 1M requests $20.00
└─ Duration 12,500,000 GB-seconds $208.33
PROJECT TOTAL $228.33
CI/CD Integration
Use our to automatically add pull request comments showing cost estimate diffs.
1. Developer/DevOps proposes a change to the infrastructure
A Developer/DevOps makes changes to the infrastructure as code file, and creates a pull/merge request.
Infracost.io Configuration 5
2. Infracost calculates the cost of the change
Infracost looks at the changes made to the Terraform file and shows the pre and post-change costs as a comment in the pull request: “This change will increase your bill by 27%”
3. Team discusses the cost implication
This enables engineering teams to see how much each pull request costs, and to peer review costs alongside the code.
Real example of how we have integrated infracost in our terraform repo:
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