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How to harden a CockroachDB container (and is cockroachdb/cockroach safe for your data?)

CockroachDB is where your transactional data of record lives: accounts, ledgers, orders, the rows an attacker most wants to read or rewrite. A stock docker run cockroachdb/cockroach:latest keeps that store behind a boundary weaker than the data deserves. Graded on IronClaw's seven-dimension containment scale, the default configuration scores 48 of 100, grade D (porous). Higher is safer. Unlike a broker or a proxy, a single-node SQL database that only its co-located application talks to can close every dimension, including the network. A few runtime flags take the same image to a full 100 of 100, grade A. Here are the exact gaps and fixes from the scan data.

Every number here comes from a read-only docker inspect of cockroachdb/cockroach:latest, the same data behind its isolation scorecard. No workload is executed. How scoring works →

Where the default configuration leaks

ironctl scan grades seven independent containment boundaries. On a default docker run cockroachdb/cockroach:latest, three fail and one warns:

Dimension Verdict Score What the scan found
Non-root user (uid != 0) ❌ FAIL 0/15 runs as root (uid 0); a container escape starts with host-uid 0
Dropped capabilities ❌ FAIL 4/20 default capability set retained (CAP_NET_RAW, CAP_MKNOD, and more)
Seccomp profile ✅ PASS 15/15 seccomp profile active
Network isolation / egress ⚠️ WARN 4/15 network=bridge: outbound egress is possible
Read-only root filesystem ❌ FAIL 0/10 root filesystem is writable
No docker.sock exposure ✅ PASS 15/15 no control socket mounted
No shared host namespaces ✅ PASS 10/10 no host PID/IPC/network sharing

The two that should worry you most are root and egress. A CockroachDB process that escapes as root escapes as root on the host, next to the very store files it was holding. And a database that can reach arbitrary destinations is one that can quietly ship your entire dataset out the moment a SQL parsing or dependency CVE lands code execution. The default capability set and writable rootfs widen and entrench that foothold.

Harden it: the exact --fix remediation

ironctl scan my-cockroach --fix prints one remediation per failed dimension, then one hardened run. For cockroachdb/cockroach:latest:

  • --user 1000:1000 (Non-root user, +15): pin a non-root uid so an escape does not begin as host uid 0. Point /cockroach/cockroach-data at a volume this uid owns.
  • --cap-drop=ALL (Dropped capabilities, +16): drop every Linux capability; CockroachDB needs none of the default set to serve SQL and its console on high ports.
  • --read-only --tmpfs /tmp (Read-only rootfs, +10): make the root filesystem read-only and mount the data directory as an explicit writable volume. Removes the persistence surface.
  • --network=none (Network isolation, +11 to the full 15): this is the dimension a co-located store can actually max out. If the only client is an application on the same host or pod reaching CockroachDB over the loopback of a shared network namespace, cut the NIC entirely. Nothing external can connect, and the database cannot phone home.

When network=none is not honest

CockroachDB is often run as a distributed cluster: nodes gossip and replicate ranges to each other over the network, and SQL clients may connect remotely. If you run more than one node, or accept remote clients, you cannot use --network=none; the store has to accept those connections. In that case put every node on a user-defined network scoped to just its peers and clients, with no default route out. That holds the network dimension at a WARN (4 of 15) and the honest ceiling becomes 89 of 100, grade B, the same as a broker. Use --network=none only for the single-node, co-located case.

Before and after

# Before: 48/100, grade D
docker run -d --name cockroach cockroachdb/cockroach:latest start-single-node --insecure

# After: 100/100, grade A (single node, co-located app, no network needed)
docker run -d --name cockroach-hardened \
  --user 1000:1000 \
  --cap-drop=ALL \
  --security-opt=no-new-privileges \
  --read-only --tmpfs /tmp \
  -v cockroach-data:/cockroach/cockroach-data \
  --network=none \
  cockroachdb/cockroach:latest start-single-node --insecure

Rescan: ironctl scan cockroach-hardened reports 100/100 grade A. A 52-point swing with no custom image build, just the right flags. Every dimension is closed because a co-located single-node database does not need to talk to anything but the app on the other side of its loopback. That is the top grade, reserved for datastores whose clients live next to them.

Verify it on your own CockroachDB

# install (Homebrew)
brew install ironsecco/ironclaw/ironclaw

# grade your running container, then print the fixes
ironctl scan my-cockroach
ironctl scan my-cockroach --fix

ironctl scan also reads a docker-compose.yml service or a Kubernetes manifest, so you can grade the CockroachDB in your stack, not just a bare docker run.

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