All our web applications use Docker for testing purporses and production enviroments and is a must inside our organization.

I think every software corporation needs to migrate their server architerture to contenerized enviroments and Docker make it easy to maintain and scale all web applications because you can have all your services or microservices running isolated and that gives you the possibility to have multiple softwares developed in different languages for every service that your application needs, for example: You can have a running container with Apache Server for your backend using PHP, and another NodeJS container for your frontend, a MySQL database service for your data and a Redis service for the cache management all in the same network sharing for every project or even for different projects in another networks, possibilities are unlimited.

In my oppion, there's no cons using Docker, I think you'll get more gains rather than pains in your software business.

Docker was first (I believe) on themarket of containerized software. There was a lot of talks that it is nothing more than an interface to unix cgroups and that docker has no future, this is just hyped piece of software. Time proved them wrong. Docker became a standard solution, participated in Open Container Initiative and while fully comply with all the OCI requirements, docker is used much widely. Container solves library/dll hell - that means that you may have two application that require incompatible libs running on the same computer without any problems. Applications are separated, they can't affect each other, their resource consumption may be tuned using docker tools. You may build proof of concept wiring containers into a single docker-compose and have the whole stack running here. Multi stage build allows to build software which does not have access to any secrets used during build step. You may use tons of software without installing it, just by running them in the docker.

Great documentation. Easy to use. Exists on any OS and platform you may need it (doesn't work with latest ARM Mac yet, but I believe this is a matter of time). Allows to you to use any software / platform / solution you want without actually installing it on your computer. Docker-compose may ran the whole stack right on your laptop and multistage builds takes care of safe software building. Free docker registry on top of that. Tremendous amount of how-to.

Some functionality behaves differently depending on platform. For example - mounted volumes. Some of issues related to file permissions stays there for at least few years. Internal volumes can not be extracted and moved to another computer easily, which somehow defeats it's purpose. Doesn't play well with WSL/WSL2 and especially if you pair it with build in kubernetes.

We are running a fleet of microservices on Amazon ECS and Docker is part of our development, testing, staging and production environments.

It's become a de-facto standard and there are a lot of resources online to learn everything, from basics to the really advanced tidbits.

Being a very complex system, sometimes it's hard to keep track of all the parts. Is runc part of Docker? What about containerd? What's moby? The fact that operating system packages with the same name include different things doesn't help. Sometimes there are also subtle bugs that take days to track and attribute to Docker.

Even if the image creation may be a complex issue, the rewards makes it worthwhile. And most of the time I can pull the image I need from a repository so I don't have to create it from scratch

It allows me to install software that otherwise the installation procedure would be too complex. I also use it to provide isolation between different software, like using different Python versions.

I don't like the procedure to create a new image, sometimes is complex. Security is also not easy to manage, since in most docker images lot of tools are disabled by default so it is hard to make updates, you have to update the base image.