What is difference between Docker and VMware?

Docker and VMware are both powerful technologies used for virtualization in IT infrastructure and application development environments. However, they each take a different architectural approach.

What is difference between Docker and VMware?

Docker uses operating system level virtualization, also known as containerization. Docker containers share the host operating system kernel and binaries. This makes Docker very lightweight and fast compared to full machine virtualization.

VMware creates fully virtualized machines that emulate real computers. Each virtual machine (VM) runs its own complete operating system and resources are allocated to each VM from the host.

Difference in Resource Allocation

One key difference between Docker and VMware is how they allocate compute resources from the host hardware:

  • Docker containers: Share host OS kernel, rely on host operating system binaries/libraries. Only self-contained app binaries and libraries are bundled inside the container. Containers have restricted access to CPU and memory resources based on configuration, but can scale up/down quickly.
  • VMware VMs: Emulate a full computer in software. Require full OS like Windows or Linux to be installed along with app binaries/libraries. VM gets dedicated CPU cores, memory allocation, storage from host hardware. More resource intensive than Docker, but fully isolated VMs.

This leads to major architectural and performance differences explored below.

Architectural Difference

Docker and VMware virtualization architectures differ significantly:

Docker Architecture

  • Docker engine runs on host OS (Linux, Windows Server)
  • Lightweight Docker containers share host kernel
  • Containers include app binaries/libraries only
  • All containers share host resources

VMware Architecture

  • VMware hypervisor runs directly on server hardware
  • Each VM includes full guest OS (Linux, Windows Server)
  • Hypervisor allocates hardware resources to VMs
  • VMs are fully isolated from each other

Performance Difference

The architectural differences lead to major performance advantages for Docker containerization compared to VMware full virtualization:

  • Docker containers have faster startup times. Typical container startup is sub-second since only the app and runtime environment needs to start, not a full OS.
  • Docker has faster reboot times. Similar to startup, only the lightweight container needs to reboot, not a full VM.
  • Docker has lower memory overhead. Containers share the host kernel and libraries so take up less RAM.
  • Docker benefits from faster app scaling. Containers can scale horizontally faster than VMs since they are so lightweight.

However, the VM approach used by VMware also has advantages:

  • VMs provide guaranteed resources allocation. Predictable CPU and RAM resource allocation since hypervisor dedicates resources to each VM.
  • VMs offer strong isolation and security. Full virtualization provides more isolation for untrusted apps compared to containers.

So there is a tradeoff – Docker provides faster, leaner virtualization while VMware provides more robust isolation for untrusted apps at the cost of reduced performance.

Difference in Portability

Docker and VMware also differ significantly in cross-platform portability:

  • Docker images are portable across any Docker environment – can take image built on a developer laptop and run on a production Linux or Windows Docker host.
  • VMware VMs are tied to the hypervisor and hardware compatibility needs to be considered during migration. Migrating a VM from VMware ESXi to Xen or other hypervisors requires conversion.

So Docker provides a portable package that can run on any compatible Docker environment. VMware VMs run only on VMware virtualization products and migration is more challenging.

When to Use Docker vs VMware

Based on the differences, here are some guidelines on when to use Docker vs VMware:

Docker Tends To Be Better For:

  • Faster startup times
  • Quick horizontal scaling
  • Lightweight microservices apps
  • Cross-platform portability
  • Development and CI/CD environments

VMware Tends To Be Better For:

  • Legacy monolithic or heterogeneous apps
  • Apps that need strong isolation or security
  • Stable production environments
  • Workloads that require guaranteed resources

Of course, many organizations use both Docker and VMware in different parts of the environment depending on the use case. The two technologies can also be used together, for example running Docker hosts within VMs or running VMware infrastructure on Docker.

Docker and VMware Feature Comparison

Feature Docker VMware
Virtualization Approach Operating system level virtualization using containers Hardware level virtualization with hypervisors
Startup Time < 1 second typical 30+ seconds
Scaling Very fast, lightweight container model Slower due to weight of VMs
Portability Images run on any Docker engine Tied to VMware hypervisor platform
Resource Allocation Shared host resources, configurable limits Dedicated resources allocated to each VM
Isolation Weaker isolation as shares host kernel Strong isolation between VMs
Use Cases Microservices, cloud native applications, lightweight apps Monoliths, legacy apps, apps needing thick isolation

Key Takeaways

  • Docker uses lightweight containers that share host resources while VMware uses full virtual machines with allocated resources.
  • Docker has faster startup, reboot, and scaling while VMware provides predictable resource allocation.
  • Docker has excellent cross-platform portability whereas VMs lock you into the VMware platform.
  • Docker suits microservices and cloud native apps. VMware suits legacy monoliths and apps needing thick isolation.
  • Many organizations run Docker and VMware side-by-side with Docker for modern apps and VMware for legacy infrastructure.

Conclusion

Docker containerization and VMware virtualization take very different approaches, leading to tradeoffs in performance, isolation, and portability. Docker provides faster, leaner virtualization using containers while VMware offers better isolation for untrusted apps with full VMs, at the cost of reduced portability and performance.

Most organizations use both technologies, leveraging Docker for modern microservices and VMware for legacy applications and stable workloads that require guaranteed resources. The two approaches can also complement each other, for example running Docker hosts within VMware VMs. Understanding the difference between Docker and VMware virtualization approaches allows architects to pick the right tool for each job.

FAQs

  1. What is the main difference between Docker and VMware?
    The main difference is that Docker uses lightweight operating system level virtualization through containers that share host resources while VMware uses full virtualization with a hypervisor allocating dedicated resources to each virtual machine.

  2. Is Docker better than VMware?
    Docker has advantages for microservices and cloud native applications due to fast startup times, lightweight containers, and portability. But VMware works better for large monolithic apps needing thick isolation and guaranteed resources.

  3. When should I use Docker vs VMware?
    Use Docker for modern, microservices based, portable cloud native applications that need to scale rapidly. Use VMware for stable infrastructure workloads and legacy monolithic applications that require strict resource allocation.

  4. Can you run Docker on VMware?
    Yes you can run Docker hosts inside VMware virtual machines to still get the isolation benefits of VMs while leveraging Docker containerization. Many organizations run Dockerized apps within VMware virtualized infrastructure.

  5. Is Docker Host the same as a VM?
    No – a Docker host provides the environment to run Docker containers so is closer to the hypervisor. The Docker host shares its kernel and host OS with containers rather than virtualizing hardware like a hypervisor.

  6. Do you need VMs if you have Docker?
    Not necessarily – many organizations choose to run Docker natively on infrastructure for optimal performance rather than virtualizing the hosts. However, others run Docker inside VMs to provide better security through isolation.

  7. How does Docker performance compare to VMs?
    Docker has faster startup times (seconds vs minutes), lower memory overhead, and much faster scale up performance compared to VMware VMs. However VMware offers predictable, guaranteed resource allocation.

  8. Can I migrate VMware VMs to Docker?
    There are tools to try to convert VM images to Docker but they may not fully convert the app correctly. It is best to rebuild legacy apps using Docker files and modern frameworks to truly move to containers.

  9. Is Docker cheaper than VMware?
    Docker Enterprise Engine itself costs less than VMware’s hypervisor and infrastructure stack. However both can have high operational costs depending on size of environment. As open source Docker and Kubernetes offer compelling lower cost options.

  10. What does VM stand for?
    VM stands for Virtual Machine – a software emulation of a full computer system including virtualized hardware, guest operating system like Linux or Windows, and applications.

Leave a Comment