The rise of WebAssembly (WASM) as a server-side runtime has led many to predict the "death of Docker." With its near-instant startup times and tiny footprint, WASM is undeniably the future of Edge computing and FaaS (Function as a Service). However, reports of Docker's demise are greatly exaggerated.
While WASM provides a high-performance sandbox, Docker provides a complete operating environment. Here are the specific use cases where Docker remains the superior choice for developers and architects.
1. Legacy "Lift and Shift" Applications
WebAssembly requires code to be compiled into the .wasm target. While languages like Rust and C++ handle this well, millions of enterprise applications run on legacy Java, Python, or Ruby versions that rely on specific OS-level shared libraries (.so or .dll files).
2. Heavyweight AI and ML Workloads (GPU Access)
Modern AI models require direct access to hardware acceleration, specifically NVIDIA GPUs via CUDA. While there are experimental proposals for WASM to interface with GPUs (WebGPU), the ecosystem is nowhere near the maturity of the NVIDIA Container Toolkit.
- Docker: Provides pass-through access to host kernels and hardware drivers.
- WASM: Operates in a strictly isolated sandbox that makes low-level hardware communication complex and slow.
3. Applications Requiring Multi-Process Management
A standard Docker container can run a primary process and several background "sidecar" processes within the same network namespace. This is common for applications that need a local logging agent, a metrics exporter, or a database proxy.
WASM runtimes are designed to execute a single module. Orchestrating multiple processes within a single WASM sandbox is contrary to its design philosophy, whereas Docker was built to handle complex, multi-faceted environments.
4. Mature Ecosystem and Tooling
Docker has had over a decade to build its ecosystem. From security scanning (Snyk, Trivy) to observability (Datadog, Prometheus) and orchestration (Kubernetes), the "Docker-native" stack is industrial-grade.
| Feature | Docker | WebAssembly (WASI) |
|---|---|---|
| Debugging | Highly mature (gdb, lldb, logs) | Improving, but difficult |
| Networking | Full TCP/UDP Stack | Restricted/Socket-based |
| Filesystem | Layered, Read/Write Access | Virtual/Sandboxed |
5. Large-Scale Microservices with Complex Dependencies
If your application depends on binary utilities—like ffmpeg for video processing, imagemagick for photo manipulation, or pandoc for document conversion—Docker is the only logical choice. In Docker, you simply apt-get install the utility. In WASM, you would have to find a WASM-compiled version of those massive libraries, which often doesn't exist or is significantly less performant.
Conclusion
WebAssembly is a scalpel—precise, fast, and perfect for specific tasks like Edge computing and plugin systems. Docker is a Swiss Army Knife—versatile, robust, and capable of carrying the weight of entire enterprise systems. For the foreseeable future, Docker remains the backbone of the modern data center.