Install

One binary covers all three surfaces — the CLI, the MCP server (lookout mcp), and the sentinel (lookout watch). Installing means getting that binary where you need it:

• On a workstation — for the CLI and the MCP server — download a prebuilt binary from the latest release (v0.13.0 and later; Linux and macOS on amd64/arm64, Windows on amd64 — Windows archives are .zip):

  gh release download -R go-steer/k8s-lookout -p 'lookout_*_linux_amd64.tar.gz'
  tar -xzf lookout_*_linux_amd64.tar.gz && sudo install lookout /usr/local/bin/

  The lookout-gke_* assets are the same binary with the GKE/GCP provider compiled in (see the flavor guide below). Or build from source with Go 1.26+:

  go install github.com/go-steer/k8s-lookout/cmd/lookout@latest

  Either way that is the whole install; lookout health against your current kubeconfig works immediately (First reads is the next page).

• In a cluster — for the sentinel — use the container images below; Deploy the sentinel applies the shipped manifests with one kubectl apply -k, no clone needed.

Container images

Images are published at ghcr.io/go-steer/lookout — multi-arch (amd64 + arm64), distroless static, running as nonroot, Sigstore-signed:

docker pull ghcr.io/go-steer/lookout:latest       # default: GCP-free, runs on any conformant cluster
docker pull ghcr.io/go-steer/lookout:latest-gke   # same binary + GKE/GCP provider (-tags allproviders)

Which flavor you need:

• Default (:latest, :vX.Y.Z) — links zero GCP SDKs, by design (a conformance test in CI keeps it that way). Most of the suite is pure client-go: the entire triage group, state edges|webhooks|volumes, stab drift|drain, bundle, health, net probe, and the sentinel sources k8s-events, object-state, rollout, saturation, degradation, expiry, and token-burn. Provider-gated commands in this image never break or lie — they emit an explicit cloud.unavailable finding and exit 0 (see Troubleshooting).
• -gke (:latest-gke, :vX.Y.Z-gke) — the same binary compiled with the GKE/GCP cloud provider. Required for the cloud command group, state wi, the perf probe metric packs, the quota source, and the capacity source’s GKE scale-decision sub-source. Same flags, same signing; only the compiled-in cloud provider differs. Project-tier deployments (the one sentinel per GCP project that enables the quota source) must pin this flavor — --sources=…,quota in the default image refuses at startup, loudly and correctly.

Verify signatures

cosign verify ghcr.io/go-steer/lookout:vX.Y.Z \
  --certificate-identity-regexp '^https://github.com/go-steer/k8s-lookout' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com

cosign verify works identically against the -gke tags.

Read the bill of materials

Every image carries an SPDX SBOM attestation per platform, signed keyless with the same identity as the signature — so the “who built this” and “what is in it” questions verify through one flow and one trust root:

cosign verify-attestation ghcr.io/go-steer/lookout:vX.Y.Z \
  --type spdxjson \
  --certificate-identity-regexp '^https://github.com/go-steer/k8s-lookout' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  | jq -r '.payload | @base64d | fromjson | .predicate' > sbom.spdx.json

Two attestations come back, one per platform (linux/amd64, linux/arm64) — a multi-arch index scanned without a platform silently describes whichever child matched the scanner’s host. This is also the checkable form of the GCP-free guarantee: the default flavor’s SBOM contains no cloud SDK, and the -gke flavor’s does.

Release binaries are covered by a keyless-signed checksums file attached to each release:

cosign verify-blob lookout_vX.Y.Z_SHA256SUMS \
  --bundle lookout_vX.Y.Z_SHA256SUMS.sigstore.json \
  --certificate-identity-regexp '^https://github.com/go-steer/k8s-lookout' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com
sha256sum -c lookout_vX.Y.Z_SHA256SUMS --ignore-missing

GKE Autopilot: both flavors run on Autopilot, with one platform limitation — Warden denies nodes/proxy to every principal, so the saturation source’s PVC dimension is disabled there (CPU/memory forecasting still works). The sentinel reports this at startup; see Concepts → Portability.

Building with a cloud provider

go install builds the GCP-free default. For a provider-enabled binary, build with tags — -tags gke for the GKE provider alone, -tags allproviders for everything (what the -gke image ships):

go build -tags allproviders ./cmd/lookout

Entrypoint

The image’s entrypoint is ["/lookout", "watch"], so a Deployment’s bare args: splice in behind watch (no explicit command: needed). The sentinel’s core flag surface is pinned by CI contract tests, so an existing deployment can upgrade the image with zero config change.

To run a read-path command from the image (rather than the sentinel), override the entrypoint — e.g. --entrypoint /lookout with docker run, or command: ["/lookout"] in a pod spec. On a workstation the natural path is the plain binary: every read command works against your current kubeconfig context, which is the next page.