egress-proxies-operator

A Kubernetes operator that manages a fleet of HTTP egress proxies for crawling: each proxy is a Proxy custom resource that the operator provisions (or merely tracks), actively health-checks through the proxy itself, and hands out to crawler clients via an HTTP list/lease API.

Architecture in 60 seconds

• Proxy CRD (crawl.example.com/v1alpha1, namespaced, kubectl get px): Managed proxies are provisioned by a configured provider; External proxies exist elsewhere and are only tracked and health-checked.
• Reconciler — a crash-safe state machine: every reconcile derives one action from (spec, status, provider Get). Proxies are immutable cattle: any meaningful spec change (placement, cloud-init, port) deletes and recreates the VM — never in-place mutation.
• Providers behind one minimal interface: kubernetes (a real Squid pod in this cluster — local dev/CI) and gcp (Compute Engine VMs with ephemeral external IPs — the real egress fleet). Config is a YAML file (--providers-config) with named instances (gcp-eu, gcp-us, ...).
• Health engine probes every proxy by fetching a URL through it (a real CONNECT tunnel — a proxy that accepts TCP but can't egress goes Unhealthy), with threshold logic and transition-only status writes.
• Discovery API (:8090): list healthy proxies filtered by attributes, lease one (least-loaded, TTL-based), release, and report rate-limiting — reports put the proxy in a per-target cooldown.
• Orphan GC sweeps each provider for tagged instances whose owning CR is gone — the safety net for crashes mid-create.

Details, diagrams, and recorded design decisions: docs/architecture.md.

Quickstart on kind (~5 minutes)

Requires: kind, kubectl, docker, Go 1.26, jq (optional). The kubernetes-pod provider needs no cloud account — proxies are real ubuntu/squid pods in the kind cluster itself.

The operator runs in-cluster for this quickstart. (Running it on your laptop with make run-dev provisions pods fine, but the health probe then originates on your machine, which cannot reach kind's pod IPs — the proxy would sit at Unhealthy forever. In-cluster, probes run where the pod network is routable.)

kind create cluster --name proxy-operator-demo
make install                                          # install the CRD
make docker-build IMG=egress-proxies-operator:dev
kind load docker-image egress-proxies-operator:dev --name proxy-operator-demo
make deploy IMG=egress-proxies-operator:dev
kubectl -n egress-proxies-operator-system rollout status deploy/egress-proxies-operator-controller-manager

Create a proxy and watch it come up:

kubectl apply -f config/samples/proxy_kubernetes.yaml
kubectl get px -w
# NAME                      MODE      PROVIDER     PHASE   IP           HEALTHY
# proxy-kubernetes-sample   Managed   kubernetes   Ready   10.244.x.x   True

Once it's Ready, port-forward the discovery API and use it:

kubectl -n egress-proxies-operator-system port-forward \
  svc/egress-proxies-operator-controller-manager-discovery-service 8090:8090 &

# List healthy proxies
curl -s 'localhost:8090/v1/proxies?healthy=true' | jq

# Lease one (5-minute TTL)
curl -s -XPOST localhost:8090/v1/leases \
  -d '{"selector":{"geo":"local"},"ttlSeconds":300}' | jq
# → {"leaseID":"...", "proxy":{"id":"default/proxy-kubernetes-sample", "ip":..., ...}}

# Actually crawl through it (from inside the cluster, or port-forward the pod)
# curl -x http://<proxy-ip>:3128 https://example.com

# Report the proxy got rate-limited by a site → 15-minute cooldown for that target
curl -s -XPOST localhost:8090/v1/leases/<leaseID>/report \
  -d '{"result":"rate_limited","target":"example.com"}'

# Release early (idempotent — 204 both times)
curl -si -XDELETE localhost:8090/v1/leases/<leaseID>

Tear down:

kubectl delete -f config/samples/proxy_kubernetes.yaml   # finalizer deletes the pod
kind delete cluster --name proxy-operator-demo

Deploying in-cluster

make docker-build IMG=<registry>/egress-proxies-operator:dev
make deploy IMG=<registry>/egress-proxies-operator:dev

• Provider config comes from the providers-config ConfigMap (config/manager/providers_config.yaml); the default ships only the kubernetes provider.

• The discovery API is exposed by the controller-manager-discovery-service Service on port 8090.

• Auth: create the token Secret, or the API serves unauthenticated (it warns loudly at startup):

  kubectl -n egress-proxies-operator-system create secret generic discovery-token \
    --from-literal=token="$(openssl rand -hex 24)"
  

GCP setup

1. Add a gcp entry to the providers config (see config/samples/providers-config.yaml) — only project is required.
2. Credentials are Application Default Credentials: workload identity in-cluster, gcloud auth application-default login locally. No key-file plumbing exists.
3. The identity needs roles/compute.instanceAdmin.v1 on the project — plus roles/iam.serviceAccountUser if instances attach a service account.
4. Managed GCP proxies must set all of placement.zone, placement.machineType, and placement.image (see config/samples/proxy_gcp.yaml, which also installs Squid via cloud-init). A missing field fails the Proxy with a message naming it.

Cloud-init from a Secret: the Secret must carry the label crawl.example.com/cloud-init: "true" — the operator's cache only holds labelled Secrets, so an unlabelled one is invisible (the Proxy reports CloudInitError). Rotating the Secret's content triggers VM replacement.

Caveats — read these two

Changing a proxy changes its IP. Proxies are immutable cattle: editing placement, cloudInit (or rotating its Secret), or port deletes the VM and creates a replacement with the same name but a new IP. Clients discover the new address via the discovery API; anything that pinned the old IP breaks by design.

Operator restart drops all leases and cooldowns. Lease state is in-memory (replicas: 1 accordingly). Clients must tolerate a lease vanishing — requests through the proxy keep working; they just re-lease. The lease store sits behind an interface so a persistent backend can replace it without touching the API handlers.

Smaller notes:

• status.lastHealthCheckTime is the time of the last status-affecting probe, not the most recent probe — status writes are transition-only by design. True probe recency lives in the metrics (proxy_operator_healthcheck_*).
• The discovery API is served by every replica but is not leader-elected; the operator ships with replicas: 1 (see the lease caveat above).

Version pins

Built and verified against the spec's pins with no substitutions needed: Go 1.26, kubebuilder v4.15.0, controller-runtime v0.24.1, k8s.io/* v0.36.3 (Kubernetes 1.36 API level), controller-tools v0.21.0, cloud.google.com/go/compute v1.65.0. envtest uses the 1.36.2 binary bundle (the latest 1.36 patch with published binaries — do not "fix" the Makefile's derived version to 1.36.3, which has none).

Development

make test        # unit + envtest suites, with -race (sets up envtest binaries itself)
go test -short ./...   # skip the envtest suite
make run-dev     # run against the current kubeconfig context

make run-dev is for iterating on the operator itself: provisioning, replacement, the discovery API, and External proxies all work from your laptop. Health checks against in-cluster pods do not (see the quickstart note) — use the in-cluster deploy to see a kubernetes-provider proxy go Ready.

Project layout, reconcile-loop diagrams, and the decision log are in docs/architecture.md; the build history is in docs/plans-executions/.