I want to use two containers Golang web server and Mysql Database.
And then I prepared two Dockerfiles and pushed on Heroku.
However web server can not be connected to mysql server.
How is link set from web server to mysql??
Thanks!
You can't link containers in Heroku unless you use the DockHero plugin there (which costs you money), so that you can use Docker Swarm. In your case it would be better just to use the ClearDB MySQL plugin they provide, and only deploy the first container.
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I am trying to understand Docker. The idea is that we can create a complete environment and have it run on any machine. But in my mind there is a problem.
Imagine that I create a Apache/PHP/MySQL application where Apache/PHP is on 1) one container and MySQL is 2) another container. Then my friend says - "Hey mate, I just created this really cool Apache/PHP/PostgreSQL application, can I run it on your server?". But he also has a Apache/PHP (different configuration) container and a PostgreSQL container. He DID NOT KNOW that there is already a Apache/PHP container running on the server. That means we will have 2 Apache and PHP installations running on the server.
If we were not using Docker we could use the same Apache and PHP. Except we would need to install some Postgres extensions. Is my understanding correct? Is this how it is done?
Is it possible to have docker installed on two servers and then using azure DevOps server, deploy the asp.net core Publish to the both servers?
If yes, I think, I need to have local registry on both servers. Then using docker-compose push the images to servers.
Am I right?
Any help would be appreciated
I’ve spent months building an application and now I’m looking to deploy it, but I’m new to Docker and I seem to have brain block when it comes to actually containerizing my application. I need to run the following technologies:
php 7.2
mysql 5.7
apache 2.4
phpMyAdmin 4.7
My application will need to be available exclusively through https and I’m assuming the connection between my application and the mysql container will also need to be through a secure port.
In addition to that I have a wordpress site that will serve as the pre-login experience for my application that I’d like to dockerize, but should not share the same DB. When I move this to a prod environment, I will not include the phpMyAdmin container.
How many containers do I need? I was thinking that I would need at least 5:
apache
php
mysql (my application)
mysql (wordpress)
phpmyAdmin
Should my application and the worpress site live in the php container? or should I create separate containers for each.
What should my docker-compose.yml file and dockerfiles look like to achieve this feat?
The driving idea here is that a container should contain a single "service". You don't break things into containers by software component (php, apache, etc.) but rather by whatever needs to be combined to create a single service. So if your application is a PHP application hosted by Apache, then you'd want a container for your application that contained PHP, Apache and your application code. That would provide your application as a service.
Same goes for Wordpress. If Wordpress is running behind Apache and needs PHP, you'd create a second container containing PHP, Apache, WordPress, and your WordPress content, producing your "Wordpress service".
Each of your individual databases can be seen as a service, so you might want two containers running MySQL, one serving each of your databases. You could choose to consider the database server as a whole to be a service, and have it serve both of your databases. Then you could get away with a single MySQL container. Which way you go with this is a minor issue. Having a single database server will likely save a little bit of resources by avoiding some duplication.
If all of your services need to talk to each other, the easiest way to do this with Docker is to use Docker Compose. This lets you create multiple containers that know about each other and can communicate very easily between each other by way of some simple DNS logic that Docker Compose provides. With Compose, you give each of your containers a simple name, and then that name can be looked up via DNS to provide the IP address of each container. So for example, if your MySql container was named "mysql", your app container could connect to it via the DNS address "mysql" with no additional work on your part.
I want to use Docker to deploy my Rails application. I want to know if there is someone tried this? And what problems can I face?
Deploying Rails apps to production with Docker is not only possible, but something you'd want to do, to make sure your app runs on any server you deploy.
This comes with some challenges. First, it's advisable to run your database server and your Rails app different containers to keep things isolated. You can also set up your production server Docker environment with Docker Machine. Machine allows you to configure AWS, Digital Ocean, Azure and Compute Engine instances (among many others), and manage your containers from your computer. I assume you're just getting started with Docker, so I suggest you take a look at this cool guide about setting up a Rails + Postgres app with Docker.
I want to migrate my current deploy to docker, it counts on a mongodb service, a redis service, a pg server and a rails app, I have created already a docker container for each but i have doubts when it comes to start and linking them. Under development I'm using fig but I think it was not meant to be used on production. In order to take my deployment to production level, what mechanism should I use to auto-start and link containers together? my deploy uses a single docker host that already runs Ubuntu so i can't use CoreOS.
Linknig containers in production is a tricky thing. It will hardwire the IP addresses of the dependent containers so if you ever need to restart a container or launch a replacement (like upgrading the version of mongodb) your rails app will not work out of the box with the new container and its new IP address.
This other answer explains some available alternatives to linking.
Regarding starting the containers, you can use any deployment tool to run the required docker commands (Capistrano can easily do that). After that, docker will restart running the containers after a reboot.
You might need a watcher process to restart containers if they die, just as you would have one for a normal rails app.
Services like Tutum and Dockerize.it can make this simpler. As far as I know, Tutum will not deploy to your servers. Dockerize.it will, but is very rough (disclaimer: I'm part of the team building it).
You can convert your fig configuration to CoreOS formatted systemd configuration files with fig2coreos. Google App Engine supports CoreOS, or you can run CoreOS on AWS or your cloud provider of choice. fig2coreos also supports deploying to CoreOS in Vagrant for local development.
CenturyLink (fig2coreos authors) have an example blog post here:
This blog post will show you how to bridge the gap between building
complex multi-container apps using Fig and deploying those
applications into a production CoreOS system.
EDIT: If you are constrained to an existing host OS you can use QEMU ("a generic and open source machine emulator and virtualizer") to host a CoreOS instance. Instructions are available from the CoreOS team.