Pros of Moby

• Comprehensive container platform with a wide range of features
• Large and active community, extensive documentation
• Supports multiple architectures and operating systems

Cons of Moby

• More complex and resource-intensive
• Steeper learning curve for beginners
• Requires more setup and configuration

Code Comparison

Gosu (simple privilege dropping):

if err := gosu.Run(uid, gid, cmd, args...); err != nil {
    log.Fatal(err)
}

Moby (running a container):

resp, err := cli.ContainerCreate(ctx, &container.Config{
    Image: "alpine",
    Cmd:   []string{"echo", "hello world"},
}, nil, nil, nil, "")
if err != nil {
    panic(err)
}

Summary

Gosu is a lightweight tool focused on running commands with different privileges, while Moby is a comprehensive container platform. Gosu is simpler and easier to use for specific tasks, whereas Moby offers a full suite of container management features but with increased complexity. Choose Gosu for simple privilege dropping in containers, and Moby for building, shipping, and running containerized applications at scale.

Pros of Tini

• Acts as a lightweight init system, handling zombie processes and signal forwarding
• Provides a more complete solution for container process management
• Supports custom entrypoints and can run as PID 1

Cons of Tini

• Slightly larger binary size compared to Gosu
• May introduce additional complexity for simple use cases
• Requires explicit installation and configuration in Dockerfiles

Code Comparison

Tini usage in Dockerfile:

FROM debian:stretch
RUN apt-get update && apt-get install -y tini
ENTRYPOINT ["/usr/bin/tini", "--"]
CMD ["your-app-command"]

Gosu usage in Dockerfile:

FROM debian:stretch
RUN apt-get update && apt-get install -y gosu
COPY entrypoint.sh /usr/local/bin/
ENTRYPOINT ["entrypoint.sh"]

Tini focuses on process management and signal handling, while Gosu primarily addresses user switching and permission issues. Tini is better suited for complex container environments requiring proper init system functionality, whereas Gosu excels in scenarios where simple user switching is the main concern. The choice between the two depends on the specific requirements of your containerized application.

Pros of dumb-init

• Handles signal forwarding and reaping of zombie processes
• Lightweight and simple to use
• Can be used as an init system for containers

Cons of dumb-init

• Limited functionality compared to gosu
• Does not provide user-switching capabilities
• May require additional configuration for complex use cases

Code Comparison

dumb-init usage:

FROM debian:stretch-slim
RUN apt-get update && apt-get install -y dumb-init
ENTRYPOINT ["dumb-init", "--"]
CMD ["my-app", "my-app-args"]

gosu usage:

FROM debian:stretch-slim
RUN apt-get update && apt-get install -y gosu
COPY entrypoint.sh /usr/local/bin/entrypoint.sh
ENTRYPOINT ["entrypoint.sh"]
CMD ["my-app", "my-app-args"]

Summary

dumb-init focuses on process management and signal handling, making it ideal for simple containerized applications. gosu, on the other hand, specializes in user-switching capabilities, which can be crucial for security and permissions management in more complex scenarios. While dumb-init is easier to implement, gosu offers more flexibility in terms of user management within containers.

Pros of baseimage-docker

• Provides a complete, init-system-enabled base image for Docker containers
• Includes useful tools and services pre-installed (e.g., SSH, cron, syslog)
• Offers better process management and zombie reaping

Cons of baseimage-docker

• Larger image size due to additional components
• More complex setup and configuration
• Potential security concerns with unnecessary services

Code Comparison

baseimage-docker:

FROM phusion/baseimage:latest
RUN /etc/my_init.d/00_regen_ssh_host_keys.sh
CMD ["/sbin/my_init"]

gosu:

FROM debian:buster-slim
RUN apt-get update && apt-get install -y gosu
COPY entrypoint.sh /usr/local/bin/
ENTRYPOINT ["entrypoint.sh"]

Key Differences

• gosu focuses on running processes with a specific user and group ID
• baseimage-docker provides a more comprehensive environment for containerized applications
• gosu is lightweight and single-purpose, while baseimage-docker offers a full-featured base image

Use Cases

• gosu: Ideal for simple containers requiring user switching
• baseimage-docker: Suitable for complex applications needing multiple services and better process management

Pros of nsenter

• Provides more advanced namespace manipulation capabilities
• Allows entering existing namespaces, not just creating new ones
• Useful for debugging and inspecting running containers

Cons of nsenter

• More complex to use and understand
• Requires root privileges or special capabilities
• Less focused on the specific use case of running commands as a different user

Code Comparison

nsenter:

int main(int argc, char *argv[])
{
    int c;
    while ((c = getopt_long(argc, argv, "+a:m:u:i:n:p:t:F:Z:r:w:S:G:", longopts, NULL)) != -1) {
        switch (c) {
        case 'a':

gosu:

func main() {
    if len(os.Args) <= 2 {
        usage()
    }

    user := os.Args[1]

Summary

nsenter is a more powerful tool for namespace manipulation, while gosu focuses specifically on running commands as a different user. nsenter offers greater flexibility but requires more expertise, whereas gosu provides a simpler solution for a common use case in containerized environments. The code snippets highlight the difference in complexity, with nsenter handling multiple options and gosu focusing on a straightforward user switch.