In Terraform AWS Provider code, we have two guiding principles for capitalization in function, constant, and variable names:
- We use Go-idiomatic MixedCaps, with idiomatic treatment of initialisms.
- We follow AWS's preferred capitalization for service names (e.g., "SageMaker" rather than "Sagemaker").
For principle 1, the golang/go Go Code Review Comments are instructive:
Words in names that are initialisms or acronyms (e.g. "URL" or "NATO") have a consistent case. For example, "URL" should appear as "URL" or "url" (as in "urlPony", or "URLPony"), never as "Url". As an example: ServeHTTP not ServeHttp. For identifiers with multiple initialized "words", use for example "xmlHTTPRequest" or "XMLHTTPRequest".
This rule also applies to "ID" when it is short for "identifier" (which is pretty much all cases when it's not the "id" as in "ego", "superego"), so write "appID" instead of "appId".
For principle 2, take a look at the AWS website for a service to see the capitalization that AWS prefers. For example, GameLift rather than "Gamelift".
To help enforce these principles, we are using semgrep rules. Below, you will find a list of the specific caps cases we look for currently. This list is generated from the same source as the semgrep rules.
NOTE: Please do NOT add "Id" to the list. Use "ID" or "id", never "Id", but we have found linter enforcement of this initialism to be too error prone because of the number of false positives for "Id" (e.g., "Identifier").
NOTE: Capitalization rules are all found in the ".semgrep-caps-aws-ec2.yml" configuration file are named <Test#>-in-func-name, <Test#>-in-var-name, or <Test#>-in-const-name, where Test# comes from the table below.
NOTE: The Test# order is wonky because we need to match on longer names first. In the future, with an option to automatically correct problems, fixing the longest possible initialism first is important (e.g., HTTPS needs to be fixed before HTTP to avoid something like HTTPs).
The caps enforced are as follows:
| Wrong | Right | Test# |
|---|---|---|
| Acl | ACL | caps1 |
| Acm | ACM | caps1 |
| AcmPca | ACMPCA | caps0 |
| Acmpca | ACMPCA | caps0 |
| Ami | AMI | caps1 |
| Api | API | caps1 |
| ApiGateway | APIGateway | caps0 |
| Appconfig | AppConfig | caps0 |
| Appmesh | AppMesh | caps0 |
| Appsync | AppSync | caps0 |
| Arn | ARN | caps1 |
| Asg | ASG | caps2 |
| Asn | ASN | caps2 |
| Autoscaling | AutoScaling | caps0 |
| Bgp | BGP | caps2 |
| Byoip | BYOIP | caps0 |
| Cidr | CIDR | caps1 |
| Cloudformation | CloudFormation | caps0 |
| Cloudfront | CloudFront | caps0 |
| Cloudwatch | CloudWatch | caps0 |
| Cmk | CMK | caps2 |
| Cname | CNAME | caps0 |
| Coip | CoIP | caps1 |
| Cpu | CPU | caps2 |
| Css | CSS | caps2 |
| Csv | CSV | caps2 |
| Dax | DAX | caps2 |
| Db | DB | caps3 |
| Dhcp | DHCP | caps1 |
| Dkim | DKIM | caps1 |
| Dlm | DLM | caps2 |
| Dms | DMS | caps2 |
| Dns | DNS | caps2 |
| Dnssec | DNSSEC | caps0 |
| DocDb | DocDB | caps0 |
| Docdb | DocDB | caps0 |
| DynamoDb | DynamoDB | caps0 |
| Dynamodb | DynamoDB | caps0 |
| Ebs | EBS | caps2 |
| Ec2 | EC2 | caps2 |
| Ecmp | ECMP | caps1 |
| Ecr | ECR | caps2 |
| Ecs | ECS | caps2 |
| Efs | EFS | caps2 |
| Eip | EIP | caps2 |
| Eks | EKS | caps2 |
| Elasticache | ElastiCache | caps0 |
| ElasticSearch | Elasticsearch | caps0 |
| Elb | ELB | caps2 |
| Emr | EMR | caps2 |
| Fifo | FIFO | caps1 |
| Fms | FMS | caps2 |
| Fqdns | FQDNS | caps0 |
| FSX | FSx | caps2 |
| Fsx | FSx | caps2 |
| Gamelift | GameLift | caps0 |
| Gcm | GCM | caps2 |
| Gp2 | GP2 | caps2 |
| Gp3 | GP3 | caps2 |
| Graphql | GraphQL | caps0 |
| Grpc | GRPC | caps1 |
| Guardduty | GuardDuty | caps0 |
| Haproxy | HAProxy | caps0 |
| Hsm | HSM | caps2 |
| Http | HTTP | caps1 |
| Https | HTTPS | caps0 |
| Hvm | HVM | caps2 |
| Iam | IAM | caps2 |
| Iot | IoT | caps2 |
| Ip | IP | caps3 |
| Ipam | IPAM | caps1 |
| Ipset | IPSet | caps1 |
| Iscsi | iSCSI | caps1 |
| Jdbc | JDBC | caps1 |
| Json | JSON | caps1 |
| Kms | KMS | caps2 |
| Mfa | MFA | caps3 |
| Msk | MSK | caps3 |
| Mwaa | MWAA | caps1 |
| Mysql | MySQL | caps1 |
| Nfs | NFS | caps3 |
| Oauth | OAuth | caps1 |
| Oidc | OIDC | caps1 |
| Opsworks | OpsWorks | caps0 |
| Php | PHP | caps3 |
| Pitr | PITR | caps1 |
| Posix | POSIX | caps1 |
| Precheck | PreCheck | caps0 |
| Qldb | QLDB | caps1 |
| Rabbitmq | RabbitMQ | caps0 |
| Rds | RDS | caps3 |
| Rfc | RFC | caps3 |
| Sagemaker | SageMaker | caps0 |
| Sasl | SASL | caps1 |
| Sdk | SDK | caps3 |
| Sfn | SFN | caps3 |
| Smb | SMB | caps3 |
| Sms | SMS | caps3 |
| Smtp | SMTP | caps1 |
| Sns | SNS | caps3 |
| Sql | SQL | caps3 |
| Sqs | SQS | caps3 |
| Ssh | SSH | caps3 |
| Ssl | SSL | caps3 |
| Ssm | SSM | caps3 |
| Sso | SSO | caps3 |
| Sts | STS | caps3 |
| Swf | SWF | caps3 |
| Tcp | TCP | caps3 |
| Tls | TLS | caps3 |
| Ttl | TTL | caps3 |
| Uri | URI | caps3 |
| Url | URL | caps3 |
| Vgw | VGW | caps3 |
| Voip | VoIP | caps1 |
| Vpc | VPC | caps3 |
| Vpn | VPN | caps3 |
| Waf | WAF | caps3 |
| Wafv2 | WAFV2 | caps1 |
| Worklink | WorkLink | caps0 |
| Workspaces | WorkSpaces | caps0 |
| Xray | XRay | caps1 |
| Xss | XSS | caps3 |
| Yaml | YAML | caps1 |