Docker vs Supervisord: What are the differences?

1. 1. Image vs Process management: Docker is primarily used for packaging applications into lightweight, portable containers known as Docker images. These images contain everything needed to run an application, including the code, runtime, system tools, and libraries. On the other hand, Supervisord is a process manager that helps in controlling and monitoring multiple processes within a single OS instance. It ensures that specified processes are running and provides a mechanism to start, stop, and restart them.

2. 2. Isolation vs Process control: Docker provides containerization, which offers significant isolation between different applications or services running on the same host. Each Docker container runs separately and has its own isolated resources, such as filesystem, network stack, and process space. Conversely, Supervisord does not provide isolation between processes. It is primarily focused on process control, helping to manage and control individual processes on a single OS instance.

3. 3. Scalability: Docker offers a scalable solution by allowing the deployment of multiple containers across different hosts, forming a Docker swarm or Kubernetes cluster. This enables horizontal scaling of applications, as containers can be easily replicated and distributed across multiple machines. On the other hand, Supervisord is not designed for managing large-scale deployments and is more suited for managing processes within a single host.

4. 4. Application Packaging: Docker is widely used for application packaging and distribution. It allows developers to build container images containing all the dependencies and configurations required for an application to run consistently in any environment. Supervisord, on the other hand, does not provide a packaging mechanism and requires manual configuration on each host where it is used.

5. 5. Portability: Docker provides a high level of portability, allowing containers to run on any host that has Docker installed, regardless of the underlying operating system. This is achieved through the use of containerization technologies such as namespaces and control groups. Supervisord, being primarily focused on process management within a single host, does not offer the same level of portability as Docker.

6. 6. Ecosystem and Community: Docker has a large and active community, with extensive documentation, tutorials, and a wide range of pre-built Docker images available in the Docker Hub. This makes it easier for developers to find solutions and troubleshoot issues. On the other hand, Supervisord does not have as large of a community or ecosystem, which may make it more challenging to find resources or support.

In Summary, Docker provides image-based isolation, scalability, packaging, portability, and a vibrant community, while Supervisord focuses on process control within a single host.