Dumb-init vs Hadolint: What are the differences?
What is Dumb-init? A minimal init system for Linux containers, by Yelp. dumb-init runs as PID 1, acting like a simple init system. It launches a single process and then proxies all received signals to a session rooted at that child process. Since your actual process is no longer PID 1, when it receives signals from dumb-init, the default signal handlers will be applied, and your process will behave as you would expect. If your process dies, dumb-init will also die, taking care to clean up any other processes that might still remain.
What is Hadolint? A Static Analysis Tool for Dockerfiles in Haskell. A smarter Dockerfile linter that helps you build best practice Docker images. The linter is parsing the Dockerfile into an AST and performs rules on top of the AST. It is standing on the shoulders of Shellcheck to lint the Bash code inside RUN instructions.
Dumb-init and Hadolint can be primarily classified as "Container" tools.
Dumb-init and Hadolint are both open source tools. It seems that Dumb-init with 3.83K GitHub stars and 212 forks on GitHub has more adoption than Hadolint with 2.28K GitHub stars and 99 GitHub forks.