How Docker Hardened Images Rescue ClickHouse Deployments Blocked by Security Scanners

<p>In late 2025, a team self-hosting Langfuse—an open-source LLM observability platform—on Kubernetes uploaded their ClickHouse image to AWS ECR as part of production preparation. The pipeline scanner flagged three critical vulnerabilities, not in ClickHouse itself, but in its base image. The security team promptly blocked the deployment, prompting a GitHub plea: <em>“Our security team is not allowing us to take it to production. Please suggest alternatives.”</em> This scenario is all too familiar for enterprise container deployments: a functional application is halted not because of broken code, but because a scanner found CVEs in packages the workload never uses. Teams spend days investigating, write risk exceptions, and still face rejection since the vulnerabilities are technically real, even if practically irrelevant.</p> <p>This article explores how Docker Hardened Images (DHI) remove that roadblock, specifically for ClickHouse—one of the most-pulled database images on Docker Hub, with over 100 million pulls. We’ll dive into ClickHouse’s architecture, why its default security posture falls short for enterprise production, and how DHI provides a hardened alternative.</p> <h2 id="the-blocked-deployment">The Blocked Deployment: A Common Enterprise Scenario</h2> <p>When the Langfuse team attempted to push their ClickHouse image to production, they encountered a typical enterprise gate: the container scanner. It reported three critical CVEs in the base image, not in ClickHouse itself. The security team’s policy required zero critical vulnerabilities for production approval, so the deployment was immediately blocked. This wasn’t an isolated incident—it reflects a broader challenge where security scanners flag theoretical risks that don’t affect the actual workload.</p><figure style="margin:20px 0"><img src="https://www.docker.com/app/uploads/2025/03/image.png" alt="How Docker Hardened Images Rescue ClickHouse Deployments Blocked by Security Scanners" style="width:100%;height:auto;border-radius:8px" loading="lazy"><figcaption style="font-size:12px;color:#666;margin-top:5px">Source: www.docker.com</figcaption></figure> <p>The team’s only recourse was to investigate each CVE, document why it couldn’t be exploited, and submit a risk exception. Even then, security teams often reject such exceptions because the vulnerabilities remain “real” in the CVE database. The result: delays, frustration, and workarounds that undermine both security and velocity.</p> <p>Enter Docker Hardened Images. These are pre-hardened base images that strip out unnecessary packages, reduce attack surface, and remediate known CVEs before they ever reach your environment. By starting from a hardened base, organizations can bypass the scanner bottleneck entirely.</p> <h2 id="clickhouse-and-its-docker-image">Understanding ClickHouse and Its Docker Image Challenges</h2> <p>ClickHouse is an open-source columnar database designed for analytical workloads at scale. It can query billions of rows and return results in milliseconds—a feat traditional row-oriented databases can’t match. Companies like Cloudflare, Uber, and Spotify run it in production, relying on its speed for real-time analytics. Its Docker image is popular (over 100 million pulls), but its default configuration prioritizes developer ease-of-use over enterprise hardening. That gap leads to the CVE friction experienced by the Langfuse team.</p> <p>The standard ClickHouse image includes a full Linux distribution with many packages (e.g., system utilities, libraries) that are not needed for the database to function. Scanners detect CVEs in these packages, triggering security blocks. Docker Hardened Images solve this by providing a minimal, purpose-built base that includes only the essentials for ClickHouse to run, eliminating unnecessary vulnerabilities.</p> <h2 id="how-docker-hardened-images-help">How Docker Hardened Images Solve the CVE Problem</h2> <p>Docker Hardened Images (DHI) are curated base images that undergo rigorous security scanning and remediation. They strip out all non-essential components, significantly reducing the number of CVEs. For ClickHouse, using a DHI means the scanner will only find vulnerabilities in packages actually required by the database—and those are regularly patched.</p><figure style="margin:20px 0"><img src="https://www.docker.com/app/uploads/2025/03/image-1024x1024.png" alt="How Docker Hardened Images Rescue ClickHouse Deployments Blocked by Security Scanners" style="width:100%;height:auto;border-radius:8px" loading="lazy"><figcaption style="font-size:12px;color:#666;margin-top:5px">Source: www.docker.com</figcaption></figure> <p>Benefits include:</p> <ul> <li><strong>No false positive CVEs</strong>: Unused packages are removed, so scanners don’t flag irrelevant alerts.</li> <li><strong>Faster security approvals</strong>: With fewer real vulnerabilities, security teams can approve deployments quickly.</li> <li><strong>Lower operational overhead</strong>: No need to investigate and write risk exceptions for every scanner finding.</li> </ul> <p>By adopting DHI, teams can move from “security blocked” to “production ready” without compromising on safety.</p> <h2 id="clickhouse-architecture">ClickHouse Architecture Overview</h2> <p>Understanding ClickHouse’s layered architecture helps appreciate why a hardened image is beneficial. ClickHouse processes SQL queries over HTTP (port 8123) or TCP (port 9000). The optimizer parses the query into an abstract syntax tree, prunes it, and passes it to the pipeline executor, which distributes work across parallel threads. At the core is the MergeTree storage engine, which stores data in columnar <code>.bin</code> files. It uses a sparse primary index to skip irrelevant granules without scanning entire columns, and runs background merges to compact parts and maintain performance.</p> <p>The storage layer is pluggable, supporting local disk, S3, and HDFS. This design enables high throughput but also means the container must include appropriate drivers and libraries. With a hardened image, only those necessary components are included, reducing the attack surface.</p> <h3>Conclusion</h3> <p>The Langfuse team’s experience is a cautionary tale for any organization deploying containers in regulated environments. Security scanners are essential, but they can create friction when base images contain irrelevant CVEs. Docker Hardened Images offer a pragmatic solution: a clean, minimal base that passes security scrutiny without sacrificing functionality. For ClickHouse users, this means faster production rollouts, less overhead, and peace of mind that the database is running on a secure foundation.</p> <p>If you’re facing similar blocks, consider switching to a hardened image. Your security team—and your release schedule—will thank you.</p>