Assignment Rules (beta)
Assignment rules allow you to control which tasks can run on which agents. Save on agent costs by provisioning different sizes of agents all with the confidence that your tasks will be run on the agents that are best suited for them. You can ensure resource intensive targets like e2e-ci and build have what they need by using larger agents. Lighter tasks like lint and test can run on smaller agents.
Assignment rules are defined in your workspaces distribution-config.yaml file. This file should be created in the .nx/workflows directory of your repository. Note that this means that you must have dynamic agents also configured in your distribution-config.yaml file.
How to Define an Assignment Rule
Each assignment rule has one of the following properties that it matches against tasks: project, target, and/or configuration. It also has a list of possible agent types that tasks with the matching properties can run on. Rules are defined in yaml like the following:
1distribute-on:
2 default: 3 linux-small-js, 2 linux-medium-js, 1 linux-large-js
3
4assignment-rules:
5 - project: app1
6 target: build
7 configuration: production
8 runs-on:
9 - linux-large-js
10 - linux-medium-js
11The above rule will match any task that has a project named app1, a target named build, and a configuration named production. Any tasks that match this rule will only be allowed to run on agents with the linux-large-js and linux-medium-js launch templates.
You can mix and match any of the criteria in an assignment rule provided that you follow the constraints:
- At least one of the following properties is defined:
project,target,configuration. - There is at least one agent type specified in the
run-onfield. - Every changeset in your
distribute-onfield must include at least one agent that matches each agent type specified in the run-on field across all assignment rules. For example, if your rules distribute tasks onlinux-small-js,linux-medium-js, andlinux-large-js, then at least one agent of each type must be available; otherwise, tasks associated with those rules cannot be executed.
Invalid Assignment Rules Example
1distribute-on:
2 # Invalid changeset that is missing `linux-large-js`. Tasks assigned to large agents won't be able to execute.
3 small-changeset: 1 linux-small-js, 2 linux-medium-js
4 medium-changeset: 2 linux-small-js, 2 linux-medium-js, 3 linux-large-js
5 large-changeset: 3 linux-small-js, 3 linux-medium-js, 4 linux-large-js
6
7assignment-rules:
8 # Missing one of `project`, `target`, `configuration`
9 - runs-on:
10 - linux-medium-js
11 - linux-large-js
12
13 # Missing `runs-on`
14 - target: lint
15 configuration: production
16
17 # Agent type not found in any of the `distribute-on` changesets
18 - project: lib1
19 target: test
20 runs-on:
21 - linux-extra-large-js
22Valid Assignment Rules Example
1distribute-on:
2 default: 3 linux-small-js, 2 linux-medium-js, 1 linux-large-js
3
4# All rules below are valid assignment rules
5assignment-rules:
6 - project: app1
7 runs-on:
8 - linux-medium-js
9 - linux-large-js
10
11 - target: lint
12 configuration: production
13 runs-on:
14 - linux-large-js
15
16 - project: lib1
17 target: test
18 runs-on:
19 - linux-medium-js
20Assignment Rule Precedence
Having multiple assignment rules means that often rules may overlap or apply to the same tasks. To determine which rule take priority, a rule of thumb is that more specific rules take precedence over more general rules. You can consult our precedence chart for a full list of rule priorities. A checkmark indicates that a rule has a particular property defined.
| Priority | Configuration | Target | Project |
|---|---|---|---|
| 1 | ✅︎ | ✅︎ | ✅︎ |
| 2 | ✅︎ | ✅︎ | |
| 3 | ✅︎ | ✅︎ | |
| 4 | ✅︎ | ✅︎ | |
| 5 | ✅︎ | ||
| 6 | ✅︎ | ||
| 7 | ✅ |
Rule Precedence Example
In this example, the task defined below can match multiple assignment rules. However, since the second rule specifies all three properties (project, target, and configuration) rather than just two (project and target), it takes precedence, and we apply the second rule when distributing the task.
1{
2 "project": "app1",
3 "target": "build",
4 "configuration": "production"
5}
61distribute-on:
2 default: 10 linux-medium-js, 8 linux-large-js
3
4assignment-rules:
5 - project: app1
6 target: build
7 configuration: production
8 runs-on:
9 - linux-medium-js
10
11 - project: app1
12 target: build
13 runs-on:
14 - linux-large-js
15Using Assignment Rules in your CI Pipeline
A typical distribution-config.yaml file might look like this:
1distribute-on:
2 small-changeset: 3 linux-medium-js, 2 linux-large-js
3 medium-changeset: 6 linux-medium-js, 4 linux-large-js
4 large-changeset: 10 linux-medium-js, 8 linux-large-js
5
6assignment-rules:
7 - project: app1
8 target: build
9 configuration: production
10 runs-on:
11 - linux-large-js
12
13 - target: lint
14 runs-on:
15 - linux-medium-js
16
17 - configuration: development
18 runs-on:
19 - linux-medium-js
20 - linux-large-js
21You can then reference your distribution configuration in your CI pipeline configuration:
1...
2jobs:
3 - job: main
4 displayName: Main Job
5 ...
6 steps:
7 ...
8 - run: npx nx-cloud start-ci-run --distribute-on=".nx/workflows/distribution-config.yaml" --stop-agents-after="e2e-ci"
9 - ..
10