In Azure Pipelines, conditions allow you to control whether certain steps, jobs, or stages run based on various criteria. These conditions can be based on the results of previous tasks, variables, or other aspects of the pipeline environment. Understanding how to use conditions effectively is key to creating dynamic and flexible CI/CD workflows in Azure DevOps. Here’s an overview of the different types of conditions and how they are used:

1. Condition Types:

   • succeeded: The default condition. The step will run if all previous steps in the job have succeeded.
   • succeededOrFailed: The step will run regardless of the success or failure of previous steps.
   • failed: The step will run only if any of the previous steps in the job have failed.
   • always: The step will always run, regardless of the success or failure of previous steps.
   • canceled: The step will run only if the run was canceled.

2. Conditional Expressions:

   • Expressions: You can use expressions to create more complex conditions, combining functions, variables, and operators. For example, you can check if a certain variable has a specific value.
   • Format: The general format for a conditional expression is condition: <expression>, where <expression> can involve variables, functions, and logical operators.

3. Using Variables in Conditions:

   • Predefined Variables: You can use predefined Azure Pipelines variables in conditions. For example, you might run a step only if the build was triggered by a pull request.
   • Custom Variables: Similarly, you can define your own variables and use them in conditional expressions.

4. Branch Conditions:

   • Branch Filters: Use conditions to run steps for specific branches, like only running a deployment step if the current branch is main or master.

5. Conditional Insertion in YAML:

   • YAML Syntax: In your YAML pipeline, you can specify conditions directly within the steps, jobs, or stages. This allows for a high degree of customization and control over the pipeline flow.

6. Environment Conditions:

   • Targeting Environments: Set conditions based on the environment. For example, you might have certain steps that only run in a production environment.

7. Dependencies Conditions:

   • Dependent Jobs: Control the execution of jobs based on the outcome of other jobs. For instance, you might have a deployment job that only runs if a build job succeeds.

8. Examples:

   • Run a step only if the previous step failed: condition: failed()
   • Run a job only on a specific branch: condition: and(succeeded(), eq(variables['Build.SourceBranch'], 'refs/heads/main'))
   • Skip a step based on a custom variable: condition: ne(variables['skipStep'], 'true')

9. Task Conditions:

   • Specific Tasks: You can apply conditions to specific tasks within a job, providing granular control over what runs and when.

10. Manual Approvals and Gates:

    • Release Pipelines: In release pipelines, you can also use conditions in conjunction with manual approvals and gates to control the deployment flow.

Azure Pipelines conditions are incredibly powerful for creating CI/CD processes that adapt to the context of the build and deployment, such as differing behaviors based on branch, build result, variables, and more. This adaptability is crucial for modern DevOps practices, allowing teams to automate their workflows intelligently. For detailed guidance and examples, the Azure Pipelines documentation is an invaluable resource.