Task 4.2: Manage runners at scale

• AGitHub wipes and reimages the machines after each job

  Incorrect

  GitHub de-registers the runner; wiping the machine is up to your automation.

• BEach runner is de-registered after it processes one job

  Correct

  The service removes an ephemeral runner's registration after one job.

• CGitHub recommends persistent runners for autoscaling, with ephemeral ones as a fallback

  Incorrect

  GitHub recommends ephemeral runners for autoscaling, not persistent ones.

• DAn ephemeral runner keeps taking jobs from the same workflow run

  Incorrect

  An ephemeral runner gets exactly one job.

• ERunner logs should be forwarded to external storage before the machines are removed

  Correct

  GitHub recommends forwarding ephemeral runners' log files to an external store for troubleshooting.

GitHub recommends autoscaling with ephemeral self-hosted runners, because it can then guarantee that only one job is assigned to each runner. Registering with --ephemeral makes the service de-register the runner after one job; your automation then wipes or replaces the machine. Ephemeral runners' log files should be forwarded to an external store before such a setup goes to production.

• Acodeload.github.com

  Incorrect

  That domain is used to download actions.

• Bghcr.io and *.pkg.github.com

  Incorrect

  Those serve GitHub Packages, not artifacts and caches.

• Cobjects.githubusercontent.com

  Incorrect

  That domain serves runner version updates.

• Dresults-receiver.actions.githubusercontent.com and *.blob.core.windows.net

  Correct

  GitHub lists these for uploading and downloading job summaries, logs, artifacts and caches; the blob storage domain isn't covered by the domains already allowed.

Self-hosted runners make outbound HTTPS connections over port 443. Besides the essential domains, uploading and downloading job summaries, logs, workflow artifacts and caches need results-receiver.actions.githubusercontent.com and *.blob.core.windows.net; other functions, such as downloading actions, packages and runner updates, need their own domains.

• AThe workflow's status badge

  Incorrect

  A badge shows pass or fail only.

• BThe repository's dependency graph

  Incorrect

  The dependency graph lists project dependencies, not runner software.

• CThe cache usage page in the Actions settings

  Incorrect

  That page shows cache sizes.

• DThe Set up job step of each run's log

  Correct

  On GitHub-hosted runners, it records the image details and links to the list of preinstalled tools.

For jobs on GitHub-hosted runners, the Set up job step records details of the runner image and includes a link to the list of preinstalled tools on that runner. The actions/runner-images repository publishes the images and their release notes.

• AACTIONS_RUNNER_HOOK_JOB_STARTED with the script's absolute path

  Correct

  The runner runs that script after a job is assigned and before it starts.

• BA first step in every workflow that deletes the leftover work directory

  Incorrect

  That changes every workflow, which the stem rules out.

• CACTIONS_STEP_DEBUG set to true

  Incorrect

  That only adds debug logging.

• DA pre-job script stored inside the actions-runner directory

  Incorrect

  Hook scripts shouldn't be kept in the runner application directory.

Self-hosted runners can run scripts before or after a job. When the ACTIONS_RUNNER_HOOK_JOB_STARTED or ACTIONS_RUNNER_HOOK_JOB_COMPLETED variable, set in the system or in the runner's .env file, holds a script's absolute path, the runner runs it. Scripts shouldn't be stored in the actions-runner directory.

• ANew runners join every group the repository can use

  Incorrect

  New runners go to the default group unless another is given.

• BRunners can be in several groups at once if each group uses different labels

  Incorrect

  Labels don't change group membership.

• CThe runners start in the default group, and each can be in only one group

  Correct

  A runner belongs to one group at a time, so the five can't be in both.

• DRunners must be re-registered to change groups

  Incorrect

  Runners can be moved between groups.

New runners are assigned to the default group unless another group is specified. A runner can be in only one group at a time, and runners can be moved from one group to another.

• Aubuntu-latest

  Incorrect

  That is a GitHub-hosted runner label.

• Bdefault only

  Incorrect

  No label named default is applied to new runners.

• Cself-hosted, linux and x64

  Correct

  Runners get the self-hosted label plus their operating system and architecture.

• DNo labels such as self-hosted or linux until an administrator adds them

  Incorrect

  Default labels are added at registration.

Self-hosted runners receive default labels: self-hosted, the operating system and the architecture. The --no-default-labels flag prevents the self-hosted label from being applied.

• AIt lost its connection to GitHub Actions for now

  Incorrect

  That is shown as Offline.

• BIt is connected and ready to take a job

  Correct

  Idle runners are connected and waiting for work.

• CIt is running a job

  Incorrect

  That is shown as Active.

• DIt was disabled by a policy

  Incorrect

  That is shown as Disabled.

A self-hosted runner's status is Idle when it is connected to GitHub and ready to execute jobs, Active while it runs a job, and Offline when it isn't connected.

• AAny account can add one after a payment method is on file

  Incorrect

  A payment method alone doesn't make larger runners available.

• BGitHub Free includes one larger runner per account

  Incorrect

  Larger runners aren't part of the GitHub Free plan.

• CLarger runners require self-hosted runner groups

  Incorrect

  Larger runners are hosted by GitHub.

• DLarger runners are for organizations and enterprises on GitHub Team or GitHub Enterprise Cloud

  Correct

  Personal accounts on GitHub Free can't add larger runners.

Larger runners are only available for organizations and enterprises using the GitHub Team or GitHub Enterprise Cloud plans, so a personal account on GitHub Free can't add one. They are hosted by GitHub, not self-hosted.

• AIt is a single-CPU runner hosted in a container on a shared VM

  Correct

  Single-CPU runners run in a container, while other hosted runners are new VMs.

• BIt runs as a runner on the team's own machines

  Incorrect

  ubuntu-slim is a GitHub-hosted label.

• CIt has more memory than ubuntu-latest

  Incorrect

  It has one CPU and less memory.

• DIt can run Docker container actions only

  Incorrect

  It is meant for light automation jobs in general, not for one kind of action.

Except for single-CPU runners, each GitHub-hosted runner is a new virtual machine. The single-CPU ubuntu-slim runner is hosted in a container on a shared VM, with one CPU and 5 GB of memory.