Google ACE Practice Question: Ensuring Successful Operation of a Cloud Solution

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  gcloud run services update-traffic my-service --to-revisions=rev2=10,rev1=90

  Why this is correct

  This is the correct service-level command for a precise traffic split between two existing revisions. It specifies both revisions explicitly, so Cloud Run routes exactly 10% of requests to rev2 and 90% to rev1; percentages must sum to 100 and should be entered as bare integers (no '%' sign). Because it uses `--to-revisions` on `update-traffic`, it works for rollbacks and gradual shifts without creating a new revision.

• ✗

  gcloud run services update my-service --traffic=rev2=10%

  Why it's wrong here

  The `--traffic` flag is not defined for `gcloud run services update`; that command updates service configuration such as image or concurrency, not traffic routing. Even if a `--traffic` flag existed, the value `rev2=10%` mixes a revision reference with a percentage sign, which is not the expected format. Traffic changes require the dedicated `gcloud run services update-traffic` subcommand with flags like `--to-revisions`.

• ✗

  gcloud run deploy my-service --image=... --traffic=rev2=10

  Why it's wrong here

  `gcloud run deploy` is intended to deploy a new revision from a container image; it does not accept `--traffic=rev2=10` because it cannot reassign traffic among two arbitrary existing revisions. The `--traffic` flag on deploy, when used, takes a single integer percentage to route to the newly created revision, so the left-hand side of the assignment would have to be omitted. For a 10/90 split between existing revisions, `gcloud run services update-traffic --to-revisions=rev2=10,rev1=90` is the correct approach.

• ✗

  gcloud run revisions update rev2 --traffic=10

  Why it's wrong here

  There is no `gcloud run revisions update` subcommand for altering routing, and revision objects themselves are immutable once created. Traffic percentages are a property of the Cloud Run service, not of an individual revision, so attempting to set `--traffic=10` on a revision is both a command error and a logical error. In Cloud Run, you attach a revision to a service and then use service-level commands to direct traffic to it.

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