In Azure DevOps, release variables play a crucial role in managing and customizing release definitions and deployment processes. These variables allow you to define configuration data that can change between different environments, releases, or build processes. Here’s an overview of how release variables work in Azure DevOps:

Types of Release Variables

1. Predefined Variables: Azure DevOps provides a set of predefined variables (similar to system variables in build pipelines) that are automatically set in each release. Examples include Release.ReleaseId, Release.EnvironmentName, and Release.DefinitionName.

2. Custom Variables: You can define your own custom variables for use in your release pipelines. These can be set at the release pipeline level or within specific environments.

Using Release Variables

• Defining Variables: You can define custom variables in the release pipeline editor. There’s an option to add new variables, where you can specify the name, value, and whether the variable is settable at release time or if it’s a secret (like passwords or keys).

• Scope of Variables: Variables can be scoped to the entire release or to specific environments. This allows for different values in different environments (e.g., different database connection strings for staging and production).

• Accessing Variables: In your deployment jobs and tasks, you can access these variables similarly to how you access system variables, typically using syntax like $(VariableName).

Security and Secret Variables

• Secret Variables: For sensitive data like passwords or API keys, you can mark a variable as a secret. Secret variables are hidden from the logs and can only be accessed by tasks in a secure way.

• Locking Variables: You can lock variables to prevent changes at release time, ensuring consistency and security.

Best Practices

1. Use Descriptive Names: Name your variables in a way that clearly indicates their purpose.

2. Limit Hardcoded Values: Use variables instead of hardcoded values in your tasks and scripts for flexibility and maintainability.

3. Use Group Variables for Common Settings: For variables that are shared across multiple pipelines, consider using variable groups.

4. Secure Sensitive Information: Always use secret variables for storing sensitive information. Additionally, consider integrating with Azure Key Vault for enhanced security.

5. Environment-specific Configuration: Utilize the scoping feature to define different values for variables in different environments.

Variable Groups

• Variable Groups: These are sets of variables that can be used across multiple release and build pipelines. They are useful for sharing common variables among multiple pipelines or when the same value is used in several places.

Accessing Release Variables in Tasks

• Variables are accessed using the $(VariableName) syntax in most tasks.
• In PowerShell or Bash scripts, they can be accessed as environment variables.

By effectively using release variables, you can create flexible and configurable release pipelines in Azure DevOps, enabling more efficient and controlled deployments across different environments.