5 Essential Steps to Overcome Security Blocks When Deploying ClickHouse on Docker

In late 2025, a team preparing to deploy Langfuse—an open-source LLM observability platform—on Kubernetes was halted by their own security scanner. The pipeline flagged three critical CVEs in the ClickHouse Docker image they had uploaded to Amazon ECR. The catch? The vulnerabilities weren't in ClickHouse itself, but in the base image's underlying packages. Despite the team arguing the flaws were irrelevant to their workload, the security team stood firm. The deployment was blocked, and the team was left scrambling for alternatives. If you've ever faced a similar roadblock during a production rollout, you know the frustration. This article walks you through five essential insights to avoid that same fate—from understanding ClickHouse's architecture to leveraging Docker Hardened Images that strip away unnecessary risks and get your container from security-blocked to production-ready.

1. The Security Block That Stops Production Deployments

Enterprise environments increasingly rely on automated container scanning to enforce security policies. When a pipeline scanner detects a vulnerability—even one that has no practical impact on your application—it can halt deployment instantly. In the ClickHouse scenario, the scanner flagged three critical CVEs in the base image's OS packages (e.g., OpenSSL or glibc). While ClickHouse itself was clean, the security team had no mechanism to differentiate real threats from theoretical ones. This leads to wasted hours: investigating findings, writing risk exception forms, and often getting rejected anyway because the vulnerabilities are technically open. The core problem isn't the scanner's accuracy—it's that the base image contains far more than what ClickHouse actually uses. To move forward, you need an image that only includes what's essential.

2. Why Base Image Vulnerabilities Matter (Even When They Don't)

At first glance, a CVE in a package that ClickHouse never calls seems harmless. And functionally, it is. But security teams operate on principle: they cannot approve a container with known, unpatched vulnerabilities. Even if the risk is low, compliance frameworks (e.g., SOC 2, PCI DSS) require remediation. The result? A deployment that is perfectly safe gets blocked by policy, not by danger. For ClickHouse—a database that powers real-time analytics at companies like Cloudflare and Uber—this creates friction between dev and ops. The only way around it is to eliminate the attack surface entirely. Docker Hardened Images achieve this by removing unused packages, libraries, and even the package manager itself, leaving only the minimal set needed to run ClickHouse. No extra packages means no extra CVEs to argue about.

3. Understanding ClickHouse's Architecture and Its Security Implications

ClickHouse is an open-source columnar database designed for analytical workloads. It processes SQL queries via HTTP (port 8123) or TCP (port 9000), passes them through an optimizer that builds an abstract syntax tree, and hands work to parallel threads for execution. The core storage engine, MergeTree, stores data in columnar .bin files with a sparse primary index to skip irrelevant granules. Below that, storage is pluggable—local disk, S3, HDFS. This layered architecture means that ClickHouse itself is lean; the complexity of the Docker image comes from the base OS layer (typically Ubuntu or Alpine). In a standard ClickHouse image, that base layer includes numerous utilities (curl, wget, perl) and libraries that never interact with the database. A hardened image strips these away, leaving only the ClickHouse binary and its direct dependencies. This not only reduces CVEs but also shrinks the image size and startup time.

4. How Docker Hardened Images Solve the CVE Problem

Docker Hardened Images (DHI) are custom-built containers that start from a minimal base—often scratch or a distroless image—and add only the binaries and libraries required by the application. For ClickHouse, this means taking the official ClickHouse binary (or building from source) and placing it into an image without a full OS layer. No shell, no package manager, no unused system utilities. The result is a container with zero or near-zero CVEs. When the same security scanner runs against a hardened ClickHouse image, it finds nothing to flag. The deployment can proceed without risk exceptions or security team debates. Many teams use DHI in combination with tools like Docker Scout or Trivy to verify the image's cleanliness before pushing to registries. This approach turns the security block into a non-issue.

5. Taking ClickHouse from Blocked to Production-Ready

To implement Docker Hardened Images for ClickHouse in your own environment, follow these steps:

• Assess your current image: Run trivy image clickhouse/clickhouse-server:latest to see the CVE baseline.
• Choose a minimal base: Use Google's distroless or an Alpine-based hardened image, or build from scratch.
• Compile ClickHouse statically (or copy the binary) and add only the necessary shared libraries (e.g., libc, libstdc++).
• Remove all package managers (apt, yum, apk) and non-essential tools.
• Test the image: Verify that ClickHouse starts, accepts connections, and runs queries correctly.
• Scan again: Confirm zero critical or high CVEs in the hardened image.

Once your hardened image passes the scanner, push it to ECR (or your registry) with a clear tag like clickhouse-hardened:24.3. Your security team can now approve the deployment without hesitation. The days of writing risk exceptions are over.

Conclusion: Deploying ClickHouse on Kubernetes doesn't have to be a tug-of-war between dev and security. By understanding the root cause of scanner blocks—overly large base images with irrelevant packages—and switching to Docker Hardened Images, you eliminate CVEs at the source. This approach not only saves time but also aligns with DevSecOps best practices: ship minimal, secure containers that are production-ready from the first scan. The Langfuse team, and many others like them, can now move forward without the security limbo. With a hardened image, your ClickHouse deployment will be both powerful and compliant.