ctcloud: CertSpotter-backed CT cloud-resource monitor

Single stateless Go process that consumes CT logs via embedded (patched)
CertSpotter internals, classifies cloud/database/storage DNS identifiers
in-process with a zero-allocation classifier, enriches via round-robin DNS
resolvers with CNAME following, and batch-writes useful findings to PostgreSQL.

- third_party/certspotter: 2-hunk IdentifierSink patch, no stdout/JSON/files
- internal/classify: AWS/Azure/GCP/Firebase/Cloudflare R2/DigitalOcean/Supabase/OCI
- internal/dns: sharded bounded TTL cache, multi-resolver load balancing + failover
- internal/pipeline: bounded queues, dedup, direct-priority load shedding
- internal/store: pgx batch writer, Postgres CT checkpoints (no cert contents)
- internal/probe: optional non-destructive reachability checks (off by default)
- Docker: distroless non-root, read-only rootfs, no app volume, resource limits
- tests enforce 0 allocs/op on the classifier and sink hot path

docker-compose.yml

@@ -0,0 +1,66 @@
+# Local / single-host deployment.
+#
+# Secrets come from .env (gitignored). Copy .env.example to .env and set a
+# strong POSTGRES_PASSWORD plus a matching DATABASE_URL before `docker compose
+# up`. For a production database, point DATABASE_URL at a TLS-enabled endpoint,
+# e.g. postgres://user:[email protected]:5432/ctcloud?sslmode=verify-full
+#
+# The compose bridge network is private; sslmode=disable is only acceptable here
+# because the database is not reachable from outside the stack.
+services:
+  postgres:
+    image: postgres:17-alpine
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER:-ctcloud}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD in .env}
+      POSTGRES_DB: ${POSTGRES_DB:-ctcloud}
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-ctcloud} -d ${POSTGRES_DB:-ctcloud}"]
+      interval: 5s
+      timeout: 5s
+      retries: 12
+    mem_limit: 1g
+    cpus: 2.0
+    pids_limit: 256
+    logging:
+      driver: json-file
+      options: { max-size: "10m", max-file: "3" }
+    restart: unless-stopped
+
+  ctcloud:
+    build: .
+    depends_on:
+      postgres:
+        condition: service_healthy
+    environment:
+      DATABASE_URL: ${DATABASE_URL:?set DATABASE_URL in .env}
+      METRICS_ADDR: ":9090"
+      LOG_LEVEL: ${LOG_LEVEL:-info}
+      DNS_SERVERS: ${DNS_SERVERS:-1.1.1.1:53,8.8.8.8:53,1.0.0.1:53}
+      DNS_WORKERS: ${DNS_WORKERS:-16}
+      ACTIVE_PROBING: ${ACTIVE_PROBING:-false}
+      # START_AT_END: "true"   # skip historical certificates on first run
+    # Metrics/health are bound to loopback only: scrape from the host or a
+    # sidecar, never expose them publicly (there is no auth on this listener).
+    ports:
+      - "127.0.0.1:9090:9090"
+    # No application volume: the container is stateless apart from PostgreSQL.
+    read_only: true
+    tmpfs:
+      - /tmp:size=16m,noexec,nosuid
+    security_opt:
+      - no-new-privileges:true
+    cap_drop:
+      - ALL
+    mem_limit: 1g
+    cpus: 2.0
+    pids_limit: 512
+    logging:
+      driver: json-file
+      options: { max-size: "10m", max-file: "3" }
+    restart: unless-stopped
+
+volumes:
+  pgdata: