Use Docker rather than native/homebrew on Mac? - docker

I currently have a LAMP stack installed on my mac running through Homebrew, which, to be honest hardly ever get's used.
Lately I have been working a lot with AngularJS and service based apps, so generally run the sites through a gulp / nodeJS based webserver.
I am totally frontend orientated, so very rarely do I play with backend related technologies other than the odd Drupal site and mysql.
I am interested to learn more NodeJS, perhaps even some Ruby, purely to understand programming more - not really for it to become my new job description.
So reading up on NodeJS a bit last night I read a lot about Docker, and installed it the toolkit and gui this morning. It looks pretty neat!
My question is: Would it work better for me to just run everything I need through Docker? For example, I can just install the mysql container, and turn it on when I need a db, and just spin up a drupal instance when I need one and connect it to my db instance?
I understand that running Docker on Mac is slower as it doesn't have the native Linux kernel and runs through a VM - but considering my needs from it, this should be okay?
I love the idea of just deploying containers, so will probably want to install Docker on my hosting environment too (VM in the cloud).
Follow up question: 90% of the sites I work on are AngularJS based frontends that speak to APIs that our backend guys build separately. Would it be overkill to have a Docker for each of those sites, or would I rather just run them all in one, or just bypass docker entirely for that (as I mentioned, I normally just load them up from within my Gulp's webserver)
Thanks a lot. I realise this is a n00b asking questions about big technology, but I'm trying to wrap my head around it and hopefully grow a bit in the process.

The interest in deploying Docker container is reproducibility.
You can easily reproduce:
either a complex development environment requiring the installation of numerous libraries (that you don't want to pollute directly your host)
or an execution environment, for a given tool to run (like a web server)
If you are not likely to repeat a setup (for dev or exec), a docker container would bring little value.
But if you want to keep track of the exact specification of an environment (through its Dockerfile) and will deploy it not just on your workstation, but in other places as well, then docker is certainly a good option to consider.

Related

Emacs workflow with development containers

New to Emacs and recently been trying to get used to it. loving it so far!
One thing I cannot seem to figure out by myself nor find any proper examples of how to figure out to following workflow:
Since I work on multiple projects with different languages and like to keep my work and private projects separated as much as possible in my OS, ive been working with development containers using docker and VScode for the past years.
This allowed me to keep both my project dependencies and the development tools in one container, where i just attached my VScode instance to a project and used extensions such as Language servers / linting / debugging from within that container.
Currently I can open my projects in emacs as the code is local and mounted to the containers, but im looking for a way to either:
Allow my local emacs to use the language/linting/debugging services installed in the container.
Install emacs in the dev containers and mount my configs to keep this synchronized.
Or better alternatives?
Most valuable would be to get language servers working again.
In case it matters, i'm working in DOOM Emacs on Arch. Mostly Python, PHP and NodeJS projects.
... use the language/linting/debugging services installed in the container
By design this is difficult to do with Docker: by design the host system can't directly access files or binaries installed in a container. Without a lot of tricks around bind mounts and user IDs and paths and permissions it's very difficult to run a program in a container in a way that looks like it's on the host system. A couple of tools have those tricks built in, but it's not at all universal. (Jenkins for example generates about 5 lines' worth of docker run command options if you ask it to run a step inside a container.)
My Emacs experience has generally been much better using a host-based per-language version manager and per-project packaging tool (a per-project node_modules directory, rbenv plus Ruby gem sets, pipenv for Python programs, ...).
In short: Emacs can't use language servers, language interpreters, or other tools from Docker images instead of the host system (without writing a lot of Lisp (and if you do consider publishing it to MELPA (and also to GitHub))).
Most valuable would be to get language servers working again.
M-x lsp-install-server will download one of the language servers lsp-mode knows about and save it in your $HOME/.emacs directory. If you activate lsp-mode and it doesn't already have a language server for the current major mode, it will offer to download it for you. There's not much to "get working" usually.

Is Docker-ized dev envoirment good for maintaining legacy software?

Let's say I have old, unmaintained application that lives on a VPS (i.e. Symfony 3 PHP app that relies on PHP 5).
If some changes are needed I have to clone this app to my desktop, build it, change and re-deploy. As time goes, recreating desktop dev environment gets harder - in this example I can't simply build the app as I use PHP7 in my CLI that breaks building process.
I tried to dockerize the app, so I added Ubuntu 18 to my docker-compose file... and it doesn't work as latest Ubuntu that has PHP5 support is 14.04. 14.04 is also the oldest (official) version available on DockerHub. But will it be still available in 3 years? If not, Docker won't build a container.
So, my question is: is Docker a right tool to solve described problem at all?
If so, should I backup docker images described that my build relies on?
If not, beside proper maintenance, what tool is better?
You can install PHP5 in newer ubuntu versions, but it means adding an external repository.
You could also create your own docker image, containing only the libraries you want. If so, I'd advise to try and use alpine as a base image. There is a bit of a learning curve to adapt, but once you do it you'll have a small image tailored to your needs.
Given that containers allow you to isolate processus and conf with minimal footprint compared to a VM, I think it is the best option. Tailoring and maintaining your own image is not that expensive in terms of maintenance if you document it correctly, and it will allow you to always have a system 'maintaining' all your precise requirements.

Docker query on containerizing

Our requirement is to create a container for legacy apps over docker.
We don't have the operating system support/application server support available, nor do we have knowledge to build them from scratch.
But we have a physical instance of the legacy app running in our farm.
We could get an ISO image from our server team if required, our question is if we get this ISO image can we export this as a docker image?
if yes, please let me know if there is any specific procedure or steps associated with it.
if no, please tell me why? and the possible workarounds for the same.
if we get this ISO image can we export this as a docker image?
I don't think there is an easy way (like push-the-export-button) to do this. Explanation follows...
You are describing a procedure taking place in the Virtual Machine world. You take a snapshot of a server, move the .iso file somewhere else and create a new VM that will run on a Hypervisor.
Containers are not VMs. They "contain" all the bytes that a service needs to run but not a whole operating system. They are supposed to run as processes on the host.
Workarounds:
You will have to get your hands dirty. This means that you will have to find out what the legacy app uses (for example Apache + PHP + MySql + app code) and build it from scratch with Docker.
Some thoughts:
containers are supposed to be lightweight. For example one might use one container for the database, another one for the Apache etc... Your case looks like you are moving towards a fat container that has everything inside.
Depending on what the legacy technology is, you might hit a wall... For example, if we are talking about something working with old php, mysql you might find ready-to-use images on hub.docker.com. But if the legacy app is a financial system written in cobol, I don't know what your starting point might be...
You will need to reverse engineer the application dependencies from the artifacts that you have in access to. This means recovering the language specific dependencies (whether python, java, php, node, etc). And any operating system level packages/dependencies that are required.
Essentially you are rebuilding the contents of that ISO image inside your docker file using OS package installation tools like apt, language level tools like pip, PECL, PEAR, composer, or maven, and finally the files that make up the app code.
So, for example: a PHP application might be dependent on having build-essential and php-mysql installed in the OS. Then the app may be dependent on packages like twig and monolog loaded through composer. If you are using SASS you may need to install ruby as well.
Your job is to track all these down and create a docker file that reproduces the iso image. If you are using a common stack like a J2EE app in tomcat, or a php app fronted by apache or ngnix, there will be base docker images that will get you most of the way to where you need to go.
It does look like there are some tools that can do this for you automatically: Dependency Walker equivalent for Linux?. I can't vouch for any of them. But you can also use command line tools. For example this will give you a list of all the user installed packages on a fedora system:
sudo dnf history userinstalled
When an app is using a dependency manager like composer or pip, there is usually a file that lists all the language specific dependencies.
At the end of the process you'll have a portable legacy app that can be easily deployed anywhere with a minimal footprint.
As one of the comments rightly points out, creating a VM from the ISO image is another way forward that will be much easier to accomplish. The application dependencies won't be explicit, but maybe that's ok for your use case.

Docker on Windows in Production

I've been asked to research Docker. The question that I cannot get a definitive response to is "can you run Docker on Windows in production?".
I keep seeing "Docker image containers can run natively on Linux and Windows. However, Windows images can run
only on Windows hosts and Linux images can run only on Linux hosts, meaning a host server or a VM."
I'm not interested in running containerized windows applications (.net). We have Spring Boot (java) applications & are creating a microservices architecture. These containerized apps. don't need an OS running in the same container.
We also need an orchestration engine like Kubernetes and its unclear if this is something that can run in production on windows either.
I've been fighting the good fight trying to get deployment environments switched to Linux but that's a loosing battle at this point.
Citing the docs:
Welcome to Docker for Windows!
Docker is a full development platform for creating containerized apps,
and Docker for Windows is the best way to get started with Docker on
Windows systems.
Take this literally. It's meant by the vendor as a dev tool to develop your Docker environment on Windows, not a production environment. To run it in production, they expect a Linux host.
It's not clear if the OP is asking "Can I run Docker on Windows in production" (like from a licensing perspective), or "should I run it" (like from an experience perspective.) I have an answer that should address both points.
It's indeed interesting to note first that as I write this, all the answers and comments so far are from 2018 or (like the question) 2017.
Here's at least one 2019 post on the topic from Docker (including listing clients running in production, so it addresses both points):
https://www.docker.com/blog/5-reasons-to-containerize-production-windows-apps-on-docker-enterprise/
And while the title refers to Docker Enterprise, the article does say "Hundreds of enterprises now run Windows container nodes in production", without that Enterprise caveat.
Even so, folks who may "not want to pay to run Docker Enterprise" should note that Windows 2016 and 2019 include a license of Docker Enterprise, free. (As for the recent upheaval of Docker where the Enterprise product was sold to Mirantis, there's no indication yet that will change the included Windows licensing of it.)
Still, I realize that the OP and other readers may seek still more (documented) evidence of production Docker deployment on Windows. I'll leave that for others to elaborate. Just didn't think this should stand here without anything more recent than July 2018.
Check out this blog, it quotes "Windows Server 2016 is the where Docker Windows containers should be deployed for production".
First of all, I suspect this question is rather stale after 3 years. I don't know if you are still struggling with the problem, I would love to hear your experience and the route you had taken.
This is probably a biased answer but I will try to answer with my experience. Like you, we have also lost the good fight to persuade our client to use a Linux server. We have 2 metals and a small bunch of virtual machines running Windows Server 2019 - Server version 1809 (Which is not the cutting edge, but the most recent stable version) It was indeed an improvement on top of WS2016. However it still had some problems. The major problem was with the docker swarm. The overlay networking with routing mesh was not working properly. So we had to fall back to containers with docker-compose and manual service discovery, which kinda beats the purpose of docker.
That being said, the problem with the Swarm network could be because of the fact that we are using virtual machines and Hyper-v switches. On top of that, we had no direct access to host network and we had to jump through some bureaucratic hoops whenever we require changes in the network, which got super old super fast when we want to test stuff. Additionally, we did not have Active Directory because of our lack of confidence to network. I am still not sure if DCs would play with docker in a virtual environment. Still not having AD was manageable since we did not have many machines.
Another problem was that we did not have nested virtualization (i.e. cannot run moby) due to CPU issues, and WSL2 with support for Docker is not available on WS19 LTSC editions. So I had to write our own images for many stuff that we use. Like Jenkins, Redis, etc. You can find the dockerfiles here if interested But obviously keeping them up to date and tidy was a huge work and I did not have much time to invest.
Performance-wise, we seemed to have no issues but we did not really make a comparative analysis.
All in all, I love Docker, it is a great product. But after this project I am thinking not to touch Docker on windows in a production environment with a 10 foot pole. In fact, I don't know if I will ever use a Windows machine as production environment in the future. It is cool to have it in development though.
My understanding is that Containers on Windows Server should be fine for production while Containers on Windows Desktop should be only for dev and test, not production. I saw one post "MICROSOFT SOFTWARE SUPPLEMENTAL LICENSE FOR WINDOWS CONTAINER BASE IMAGE" https://learn.microsoft.com/en-us/virtualization/windowscontainers/images-eula, not sure how this one is related to this question?
I can highly recommend not to use Docker Desktop for Windows in Production.
The host machines (Windows 10 Pro) where configured to restart everyday at a certain time and the Docker Container where Linux containers which as recommended where using the WSL2 based engine.
I was testing it on 20 devices for a over one year now and from 20 Pc's had at least 5 now the problem that Docker Desktop cannot be initialized. Which means that Docker Desktop is not starting anymore until you remove some folder(s) in %APPDATA% but when you do so it worked only 3 out of 5 times for me that Docker Desktop was able to start after that. One time needed to reinstall Docker Desktop the remaining One I needed to reload all the docker images and configure them again. Most of the issues seemed to have been a result of a power cut.
Most annoying are the updates from my perspective, because from one to the other version all images and running containers where gone and I needed to reconfigure them, happend with 2 Version in the past but not on all computer.
The Linux machines on the other hand no issues.

Using Vagrant and Docker together, by example

So this weekend I installed both Vagrant and Docker on my laptop and played around with them a little bit. I totally understand that they are different beasts with different intentions in mind. But I can't help to think: how could they be used to complement each other?
If you Google "Docker vs Vagrant" you'll get an ocean of blogs and articles stating how these two technologies are different. But I have yet to come across a single concrete article demonstrating how these two technologies can be used with each other. I assume there has to be specific scenarios where one would use both, otherwise there would be no reason to have the Vagrant-Docker provisioner.
So I ask: Can someone please provide me with a concrete scenario(s) in which a dev would use both Docker and Vagrant? Perhaps using Vagrant to manage a local VM and then perhaps Docker for "converting" that configured (with deployed application in tow) VM to a container, or something thereabouts?
I'm looking for specific, fairly detailed scenarios here! Thanks in advance!
This question is very broad but for dev environments you can use as your creativity spans.
So one scenario that I can think of is that you are running say Ubuntu in your production environment with Docker containers. Say your developers have Mac OS X machines running VirtualBox, but you want want their environment to be as close as possible to the production environment. So use Vagrant with Ubuntu VM and in that VM run Docker containers.
The same can be said about Windows machines, what if your production environment is all Ubuntu with Docker. You can emulated with Vagrant and VirtualBox too.
Often considered two alternative tools, Docker and Vagrant can be used
together to build isolated and repeatable development environments. We
will prove it setting up a Docker container for development of a Java
application and taking advantage of Vagrant powerful features to solve
some real life practical issues.
https://blog.zenika.com/2014/10/07/setting-up-a-development-environment-using-docker-and-vagrant/

Resources