Overview The env_vars section checks for the presence of environment variables and optionally validates their values against regex patterns. This ensures critical configuration values are set before running your application.
Configuration Each environment variable check is defined by an EnvVarCheck struct (src/config.rs:31) with the following fields:
The name of the environment variable to check.
Whether the environment variable must be set. If true, validation fails when the variable is not defined.
A regex pattern to validate the variable’s value. If specified, the value must match this pattern.
Examples Basic Presence Check Check that an environment variable is set:
env_vars : - name : DATABASE_URL required : true
Optional Variables Mark variables as optional when they have sensible defaults:
env_vars : - name : NODE_ENV required : false - name : LOG_LEVEL required : false
Pattern Validation Validate that environment variable values match expected formats:
env_vars : - name : RAILS_ENV required : false pattern : "^(development|test|production)$" - name : DEBUG required : false pattern : "^(True|False|1|0)$" - name : PORT required : true pattern : "^[0-9]{1,5}$"
Real-World Examples Node.js Project
Django Project
Rails Project
Rust Project
Go Project
version : "1" env_vars : - name : NODE_ENV required : false - name : DATABASE_URL required : true
Pattern Syntax The pattern field uses standard regex syntax. Here are common patterns:
Exact Values # Must be one of: development, test, production pattern : "^(development|test|production)$"
Boolean Values # Common boolean representations pattern : "^(true|false|1|0|yes|no)$" # Python-style booleans pattern : "^(True|False|1|0)$"
Numeric Ranges # Port numbers (1-65535) pattern : "^([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$" # Simple 1-5 digit number pattern : "^[0-9]{1,5}$"
URL Validation # Simple URL pattern pattern : "^https?://.*" # Database URL pattern : "^postgres(ql)?://.*"
# Alphanumeric only pattern : "^[a-zA-Z0-9]+$" # Semantic version pattern : "^[0-9]+ \\ .[0-9]+ \\ .[0-9]+$"
Remember to escape backslashes in YAML strings. Use \\ for a single backslash in regex patterns.
Default Behavior From the struct definition in src/config.rs:31:
name: Required field, no defaultrequired: Defaults to truepattern: Defaults to None (no pattern validation)
When required: true, validation fails if:
The environment variable is not set
The variable is set but its value doesn’t match the pattern (if specified)
Use required: false with a pattern to validate optional variables only when they’re set. This allows developers to omit the variable entirely while ensuring correct values when provided.
