pool.demands definition

Implementations

Remarks

Use demands to make sure that the capabilities your pipeline needs are present on the agents that run it. Demands are asserted automatically by tasks or manually by you.

You can check for the presence of a capability (Exists operation) or you can check for a specific string in a capability (Equals operation). Checking for the existence of a capability (exists) and checking for a specific string in a capability (equals) are the only two supported operations for demands.

Task demands

Some tasks won't run unless one or more demands are met by the agent. For example, the Visual Studio Build task demands that msbuild and visualstudio are installed on the agent.

Manually entered agent demands

You might need to use self-hosted agents with special capabilities. For example, your pipeline may require SpecialSoftware on agents in the Default pool. Or, if you have multiple agents with different operating systems in the same pool, you may have a pipeline that requires a Linux agent.

Exists operation

The exists operation checks for the presence of a capability with the specific name. The comparison is not case sensitive.

pool:
 name: MyPool
 demands: myCustomCapability # exists check for myCustomCapability

Equals operation

The equals operation checks for the existence of a capability, and if present, checks its value with the specified value. If the capability is not present or the values don't match, the operation evaluates to false. The comparisons are not case sensitive.

pool:
 name: MyPool
 demands: Agent.Version -equals 2.144.0 # equals check for Agent.Version 2.144.0

Agent variables as system capabilities

Self-hosted agents have the following system capabilities with similar names to agent variables, but they are not variables and don't require variable syntax when checking for exists or equals in a demand.

• Agent.Name
• Agent.Version
• Agent.ComputerName
• Agent.HomeDirectory
• Agent.OS
• Agent.OSArchitecture
• Agent.OSVersion (Windows agents only)

Agent capability scanning

When the agent software starts, it scans for the following software and tools and registers the corresponding capabilities.

demands: string # Specify a demand for a private pool.

Examples

To add a single demand to your YAML build pipeline, add the demands: line to the pool section.

pool:
 name: Default
 demands: SpecialSoftware # exists check for SpecialSoftware

demands: [ string ] # Specify a list of demands for a private pool.

Examples

To specify multiple demands, add one per line.

pool:
 name: MyPool
 demands:
 - myCustomCapability # exists check for myCustomCapability
 - Agent.Version -equals 2.144.0 # equals check for Agent.Version 2.144.0

See also

• Agent capabilities