I am very very new to Docker and trying to really wrap my head around the concept and also struggling a little bit. While I have not created any image yet but my team is moving to Docker and I do have very fundamental questions. Let me start with what I understand
I can create an Image of my application which can consist of OS version, Web server configuration and Applicaton binaries
However what I do not understand is that there are far more things involved in n-tier application and I have a lot of questions which I am struggling to find answers for. i just wanted to post some of them here and see if some of them can be clarified.
As I just mentioned above an n-tier application has far more things involved than my Binaries and web server settings. If I have multiple layers(Binaries) for my application say one for services and one for MVC client then do I need an image per layer?)
What happens to .config files? One thing that confused me a lot is that it is mentioned that you can use the same image for testing and prod. Then something has to be different across these environments right? Would that something be config files? if yes then why it is not mentioned anywhere?
What happens to DB? Do we spin up another image for DB?
I am hope I am not very far off on my assumptions.
Related
I am new to Docker and want to learn the ropes with real-life challenges.
I have an application hosted on IIS and has dependencies over SQL Express and SOLR.
I want to understand the following:
Is it possible to have my whole set-up, including of enabling IIS,
SQL, SOLR and my application in one single container?
If point 1 is feasible, how should I start with it?
Sorry if my questions are basics.
It is feasible, just not a good practice. You want to isolate the software stack to improve the mantainability (easier to deploy updates), modularity (you can reuse a certain component in a different project and even have multiple projects reusing the same image) and security (a software vulnerability in a component of the stack will hardly be able to reach a different component).
So, instead of putting all together into the same image, I do recommend using Docker Compose to have multiple images for each component of the stack (you can even pull generic, up-to-date images from Docker Hub) and assemble them up from the Compose file, so with a single command you can fire up all the components needed for your application to work.
That being said, it is feasible to have all the stack together into the same Dockerfile, but it will be an important mess. You'll need a Dockerfile that installs all the software required, which will make it bulky and hard to mantain. If you're really up for this, you'll have to start from a basic OS image (maybe Windows Server Core IIS) and from there start installing all the other software manually. If there are Dockerfiles for the other components you need to install and they share the same base image or a compatible one, you can straight copy-paste the contents into your Dockerfile, at the cost of said mantainability.
Also, you should definitely use volumes to keep your data safe, especially if you take this monolithic approach, since you risk losing data from the database otherwise.
TL;DR: yes, you can, but you really don't want to since there are much better alternatives that are almost as hard.
I've been learning Travis CI and I want to use it to help automate tests on a MEAN application, then deploy it. However, there are some ways to go about this.
After reading, I learned I can create two separate repositories, thus maintaining two separate applications: a client application and a backend application. Since they are separate repositories, I can have separate .travis.yml files on each and perform continuous integration on the client application and backend application. However, I need advice on this approach because I have questions:
For the client app, I have to write tests. Since I'll be using angular, I want to test responsiveness and if components are working as intended. The client application also has to communicate with the backend application and I want to see if it is properly getting the correct results (such as clicking a button triggers a GET request and see if I'm getting the correct response body). Since the client app is on a separate repository, and when I build it on TravisCI, how will I connect the client application to the backend application if it exists on a separate repository?
I read around and I can use submodules in git. Thus, the client application and the backend application can be submodules for a 'master repository'. Therefore, how will the trigger in TravisCI work? Will I have separate travis.yml files in each submodule, or will I have to have one in the "master repository"?
If I were to get everything to work properly and have the client application and backend application both successfully deploy and the two are hosted on different servers, how will I fix the cross-domain issue?
The other approach is to host the static files produced by ng build --prod and have the node backend application host them. When Travis CI is triggered, I can first build the node backend application and run the tests on it first and then run the tests on the angular client application. After all of the tests are passed, where do I deploy? I know I have to deploy the node application since it will host the static files, so I how exactly will I deploy the backend application in Travis CI?
I know this is going to push it, but I'll ask it anyway. In the future, I want to learn how to implement microservices, and I want to use Nginx for the purpose of load balancing. How will I go about that? Docker can help me create a production environment where I can see if the Nginx server and node application are working well, but how do I include that in Travis CI?
If my question is a bit vague, please let me know what parts of it are vague so I can edit it that way I can make more sense of what I'm asking for. Thank you, and I look forward to an answer :)
Question is ultra-broad. You should solve one problem at a time, because by the time you solve 1 and 2 I doubt that 3 will be your only concern, and all of these issues are not really related.
try spending a bit of time reading Travis CI documentation, but also how to write tests and what different types of tests will do for you. Your issue is less about Travis than about what are unit tests vs. what are integration tests. So write simple standalone tests for your frontend, simple standalone tests for your backend, maybe run integration tests manually for a while, and when it becomes a real issue, then you will have better knowledge of how everything works together and you will find a way. Long story short: there is no single best way to run integration tests and it mostly depends on many, many things in your app (how does it run, what type of DB do you use, etc.)
you should read about submodules. Perhaps you need them, perhaps not. There is no way to tell. You can use submodules with Travis CI, but you can also not use submodules. Depends on what you want to achieve. Focus on the end goal for your architecture, not on what Travis CI needs!
what cross-domain issue? Again, this is a very different problem, and probably not the most prominent one you will face. Since I have no idea what server technology you will use there is no way I can answer that question properly. If you use express, this may be what you are looking for: https://expressjs.com/en/resources/middleware/cors.html
General bit of advice: all of your questions boil down to experience. Try solving one problem at a time, get started with your project and when you hit a specific issue, it's much much easier to solve than asking about "microservices". There are many ways to do microservices right, each solving a different issue. Without any knowledge of what your application is about and what issues you want to solve, microservices may or may not be what you are looking for, but there are also many other components that can affect your stack. Just get started and don't think about all of this too much for now - it's better to have something soon that you can test and learn upon, than think for weeks about something that you will never get because it is only theory.
I'm starting with Kubernetes (through GKE) and I want to setup Gitlab Review Apps.
My use case is quite simple. I've read tons of articles but I could not find clear explanations and best practices on the way to do it. This is the reason why I'm asking here.
Here is what I want to achieve :
I have a PHP application, based on Symfony4, versioned on my Gitlab CE instance (self-hosted)
I setup my Kubernetes using GKE into Gitlab
I want, on each merge request, deploy a new environment on my cluster where I am able to test the application and the new feature (this is the principle of Review Apps).
As far as I read, I've only found simple implementations of it. What I want to do, is deploy to a new LAMP (or LEMP) environment to test my new feature.
The thing that I don't understand is how to proceed to deploy my application.
I'm able to write Docker files, store them on mi Gitlab registry, etc ...
In my use case, what is the best way to proceed?
In my application repository, do I have to store a Docker file which includes all my LAMP configuration (a complete image with all my LAMP setup)? I don't like this approach, it seems strange to me.
Do I have to store different custom images (for Apache, MySQL, PHP-FPM, Redis) on my registry and call them and deploy them on GKE during review Stage in my gitlab-cy.yml file?
I'm a little bit stuck on that and I can't share code because it's more about the way to handle everything.
If you have any explanations to help me, it would be great!
I can, of course, explain a little bit more if needed!
Thanks a lot for your help.
Happy new year!
Recently I have been dabbling in Ruby on Rails by learning it through Michael Hartl's tutorial and various other resources on the net. I'm quite impressed with it and have a number of ideas for applications I want to write with it.
Heroku seems like a really nice option for deploying these applications - it's smooth and extremely easy to set up, which is great. Something that I'm not clear on, however, is the type of projects Heroku is best suited for. This might seem like a subjective question, but keep in mind that I am asking from an entirely technical aspect (for instance, "Heroku is most used for X because of Y"), trying to figure out which option would work best given the type of projects I'm interested in.
With that said, I have three basic types of applications I'd like to write:
A personal site with a blog front page and several content pages
A community site that acts as a repository for Illustrator ".ai" files with forums and possibly a wiki
An image host with forums
For each of these projects, which would be best: Heroku, a traditional host with RoR support, or a different cloud host with RoR support?
Heroku is designed for any kind of webapp really. It is designed to scale well depending of your needs.
If you want to host user files you will have to use an outside service like amazon S3, because heroku is not designed to upload files directly in the application. Which is a good practice.
http://devcenter.heroku.com/articles/slug-size
http://devcenter.heroku.com/articles/s3
http://aws.amazon.com/s3/
How can i write a cloud-aware application? e.g. an application that takes benefit of being deployed on cloud. Is it same as an application that runs or a vps/dedicated server? if not then what are the differences? are there any design changes? What are the procedures that i need to take if i am to migrate an application to cloud-aware?
Also i am about to implement a web application idea which would need features like security, performance, caching, and more importantly free. I have been comparing some frameworks and found that django has least RAM/CPU usage and works great in prefork+threaded mode, but i have also read that django based sites stop to respond with huge load of connections. Other frameworks that i have seen/know are Zend, CakePHP, Lithium/Cake3, CodeIgnitor, Symfony, Ruby on Rails....
So i would leave this to your opinion as well, suggest me a good free framework based on my needs.
Finally thanks for reading the essay ;)
I feel a matrix moment coming on... "what is the cloud? The cloud is all around us, a prison for your program..." (what? the FAQ said bring your sense of humour...)
Ok so seriously, what is the cloud? It depends on the implementation but usual features include scalable computing resource and a charge per cpu-hour, storage area etc. So yes, it is a bit like developing on your VPS/a normal server.
As I understand it, Google App Engine allows you to consume as much as you want. The back-end resource management is done by Google and billed to you and you pay for what you use. I believe there's even a free threshold.
Amazon EC2 exposes an API that actually allows you to add virtual machine instances (someone correct me please if I'm wrong) having pre-configured them, deploy another instance of your web app, talk between private IP ranges if you wish (slicehost definitely allow this). As such, EC2 can allow you to act like a giant load balancer on the front-end passing work off to a whole number of VMs on the back end, or expose all that publicly, take your pick. I'm not sure on the exact detail because I didn't build the system but that's how I understand it.
I have a feeling (but I know least about Azure) that on Azure, resource management is done automatically, for you, by Microsoft, based on what your app uses.
So, in summary, the cloud is different things depending on which particular cloud you choose. EC2 seems to expose an API for managing resource, GAE and Azure appear to be environments which grow and shrink in the background based on your use.
Note: I am aware there are certain constraints developing in GAE, particularly with Java. In a minute, I'll edit in another thread where someone made an excellent comment on one of my posts to this effect.
Edit as promised, see this thread: Cloud Agnostic Architecture?
As for a choice of framework, it really doesn't matter as far as I'm concerned. If you are planning on deploying to one of these platforms you might want to check framework/language availability. I personally have just started Django and love it, having learnt python a while ago, so, in my totally unbiased opinion, use Django. Other developers will probably recommend other things, based on their preferences. What do you know? What are you most comfortable with? What do you like the most? I'd go with that. I chose Django purely because I'm not such a big fan of PHP, I like Python and I was comfortable with the framework when I initially played around with it.
Edit: So how do you write cloud-aware code? You design your software in such a way it fits on one of these architectures. Again, see the cloud-agnostic thread for some really good discussion on ways of doing this. For example, you might talk to some services on GAE which scale. That they are on GAE (example) doesn't really matter, you use loose coupling ideas. In essence, this is just a step up from the web service idea.
Also, another feature of the cloud I forgot to mention is the idea of CDN's being provided for you - some cloud implementations might move your data around the globe to make it more efficient to serve, or just because that's where they've got space. If that's an issue, don't use the cloud.
I cannot answer your question - I'm not experienced in such projects - but I can tell you one thing... both CakePHP and CodeIgniter are designed for PHP4 - in other words: for really old technology. And it seems nothing is going to change in their case. Symfony (especially 2.0 version which is still in heavy beta) is worth considering, but as I said on the very beginning - I can not support this with my own experience.
For designing applications for deployment for the cloud, the main thing to consider if recoverability. If your server is terminated, you may lose all of your data. If you're deploying on Amazon, I'd recommend putting all data that you need persisted onto an Elastic Block Storage (EBS) device. This would be data like user generated content/files, the database files and logs. I also use the EBS snapshot on a 5 day rotation so that's backed up itself. That said, I've had a cloud server up on AWS for over a year without any issues.
As for frameworks, I'm giving Grails a try at the minute and I'm quite enjoying it. Built to be syntactically similar to Rails but runs on the JVM. It means you can take advantage of all the Java goodness, like threading, concurrency and all the great libraries out there to build your web application.