Multiple machines

Build Environment Running Tests
1

I need to run benchmark tests as part of a CI run. These tests are performance-sensitive, and so they require separate VMs for each component (database, search engine, etc.).

From what I can tell, each job can only run on one machine. Is there no support for provisioning multiple machine resources and scheduling steps to run on them?

2

You should be able to make use of matrix jobs to specify a matrix of resource classes:

As an example, this would build on the medium and large resource classes with machine executor:

version: 2.1

jobs:
  build:
    parameters:
      resource:
        type: string
    resource_class: << parameters.resource >>
    machine:
      image: ubuntu-1604:202007-01
    steps:
      - run: echo 1

workflows:
  workflow:
    jobs:
      - build:
          matrix:
            parameters:
              resource: ["medium", "large"]
3

That only runs the test on one machine at a time, though, as far as I can see. I’m asking about starting multiple machines during a single build, and scheduling different job steps on them. Considering that CircleCI supports detached steps with background: true, I’m surprised there’s no way to tell it where to run the steps.