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pool.demands definition

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Demands (for a private pool).

Definitions that reference this definition: pool

Implementations

Implementation Description
demands: string Specify a demand for a private pool.
demands: string list Specify a list of demands for a private pool.

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.

Note

Demands and capabilities are designed for use with self-hosted agents so that jobs can be matched with an agent that meets the requirements of the job. When using Microsoft-hosted agents, you select an image for the agent that matches the requirements of the job, so although it is possible to add capabilities to a Microsoft-hosted agent, you don't need to use capabilities with Microsoft-hosted agents.

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)

demands: string

Specify a demand for a private pool.

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

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 list

Specify a list of demands for a private pool.

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

List types

Type Description
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