Azure DevOps doesn't provide a direct built-in feature to conditionally start a release stage based on the presence of a specific artifact in a release pipeline. However, you can achieve this using a combination of release gates and conditions. Here's how you can approach it:
1. **Release Gates:**
You can use the "Gates" feature in Azure DevOps to introduce conditions before a release stage starts. You would set up a release gate that checks whether the specific artifact exists. If the condition is not met, the gate will block the stage from starting. You can create custom release gates using scripts or use predefined gates like "Artifact download."
2. **Release Stage Conditions:**
While you can't directly conditionally start a stage based on artifact presence, you can control the conditions under which a stage runs. Each release stage can have a "Run on agent" condition that can be customized using pre-defined expressions. You could potentially use variables in these conditions to control the behavior.
Here's a high-level guide on how you might set up this kind of conditional behavior:
1. **Artifact Naming Convention:**
Ensure your build pipeline produces artifacts with clear naming conventions that indicate their purpose (e.g., Artifact1, Artifact2).
2. **Release Gates:**
Set up a release gate (using scripts or predefined gates) that checks for the presence of a specific artifact. If the artifact doesn't exist, the gate would block the stage from starting.
3. **Release Stage Conditions:**
For each release stage, use the "Run on agent" condition to control the stage's behavior. You can use predefined variables like `$(Release.Artifacts.{artifact alias}.SourceVersion)` to check if the artifact exists or has a specific version.
For example, you could set a condition like:
```
and(succeeded(), eq(variables['RELEASE_ARTIFACT1_PRESENT'], 'true'))
```
To set these conditions dynamically, you might need to script the release pipeline YAML or use REST API calls to update the release stages' conditions based on the status of the gates.