Dockerizing an Existing Rails Application

[@Coderjourney]

What did you think of the tutorial? I thought I might have went a little too fast.

[@cmendla]

I actually bumped the speed to 1.25. If someone things you are going to fast they can go to .75.

[@armanmirk]

don't know why this video doesn't have more likes but I suspect for most developers this is the video to watch.

[@Coderjourney]

+Mirkury wow that is such a compliment! I really appreciate that. Thank you

[@rameshdoraiswamy3194]

Pretty informative. Thanks a lot Keith. Looking for more of your great educational videos on Docker Swarm.

[@Coderjourney]

+Ramesh Doraiswamy I'm glad you're finding these useful. Not sure when exactly I'll be digging into Docker Swarm. Please Chime in with any topic suggestions you've got by going to coderjourney.com/survey

[@conradtaylor29]

Very helpful video and timely as well because I'm looking to Dockerizing an existing app as well.

[@ThePolaris87]

Awesome, just started working with a Rails + Docker project and this was very helpful, thanks!

[@Coderjourney]

Awesome. I’m glad you’re finding this useful.

[@manishspuri]

awesome very helpful..!

[@tommoa5225]

I like it. It was a nice overview that gave me an idea of what to expect when Dockerising a rails app. I am curious though. Would you say this is a prerequisite to building images for deployment on a Kubernetes cluster? I have just started learning k8s and came across this video while I attempt to understand the process of app deployments.

[@Coderjourney]

I’m glad that you liked it. Knowledge of how to build a docker image is definitely something that I would suggest before digging into kubernetes.

[@edisonleon7174]

Great tutorial series, Thank you!

[@Coderjourney]

+Edison Leon you're welcome, I'm glad you're liking it. I have some Docker courses over at courses.coderjourney.com if you're wanting to dig deeper.

[@ericzhou3102]

why are the 'POSTGRES_USER' and 'POSTGRES_PASSWORD' parameters in dock-compose.yml left blank? I think it will make the db container running without user and password,right?

[@Coderjourney]

Leaving the value blank tells docker-compose to substitute in the environment values from the machine running the docker-compose command. This lets us set environment variable locally before running the command to change behavior of the started container without needing to change any files.

[@Norm7264]

unless I'm misunderstanding (not unlikely!), it looks to me that the postgres data does not persist in the event of the app being taken down and then up. Is that right? If so, it seems as if this would be a requirement for a live app.

[@Coderjourney]

+Les Nightingill you’re legitimately the only person who’s ever noticed that typo. The volume mapping should be to /var/lib/postgresql/data instead. Not sure why pgsql came to mind when I recorded this.

[@juanpmarinr]

Very helpful tutorial!! I'm learning english so I don't understand what is "external: false" for, can you help me please ? Thaks !

[@Coderjourney]

+Juan Pablo Marín "external: false" tells docker-compose that it should create and manage the volume because we aren't using a volume that we created manually, outside of docker-compose. I hope that helps.

[@MrUntiendX]

Thanks for the tutorial. I have to specify explicitly POSTGRES_USER: 'value' and POSTGRES_PASSWORD: 'value' in docker-compose file? How come for you works without them specified?

[@Coderjourney]

If they are exported into your shell’s environment before running the docker-compose commands then they will be passed through if you don’t provide a value in the YAML file.

[@batorshikh.baavgaikhuu]

I didn't get any log message after docker-compose run --rm app rake db:migrate. But my schema.rb changed. What do you think? thanks.

[@batorshikh.baavgaikhuu]

Is there an any configuration or option to print log into terminal?

[@batorshikh.baavgaikhuu]

And I have a many migration file. It's so strange rake didn't response any log message.

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu is you imported your database file then there wouldn’t be any migrations to apply (because the database state would match). In that case there wouldn’t be much of any output.

[@batorshikh.baavgaikhuu]

Oh, yes. I got it. thank you.

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu you’re welcome. Glad I could help.

[@batorshikh.baavgaikhuu]

Hello How can I run my container as production env?.

[@Coderjourney]

You can add a “RAILS_ENV: production” entry to the environment list in docker compose (or an env file)

[@batorshikh.baavgaikhuu]

Hi again. Should I rebuild image after some code changes?

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu in development if you aren’t sharing through a volume then you will need to rebuild the image to get code changes to show up. Outside of development you will always need to rebuild when there is a code change. There are a few other issues that can pop up in development: 1) your code might be updating, but the app isn’t reloading it. Check for a line about “listen” in the development config and comment it out if it is there 2) macOS High Sierra seems to have broken some file sharing with virtualbox and I haven’t quite found a way around it.

[@batorshikh.baavgaikhuu]

Okay, Thank you. I'll try.

[@batorshikh.baavgaikhuu]

My files updating, but the app isn't reloading that changes. What should I do?

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu does your app use the “listen” gem?

[@batorshikh.baavgaikhuu]

No. I haven't listen gem. Should I use it?

[@batorshikh.baavgaikhuu]

Hi. My all configurations are done(DB, APP). But My app is running so slow, I'm using docker on mac. I also run my app on real UBUNTU OS and its running fine.

[@batorshikh.baavgaikhuu]

Do you know about that?

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu the file system sharing between Mac and Docker can be really slow. I avoid using Docker for Mac for that reason (though I may have used that for these tutorials). I would try switching to using docker-machine and also brew install docker-machine-nfs to run to configure a faster file system share.

[@batorshikh.baavgaikhuu]

Should I reconfigure app environment on docker machine ?

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu it’s worth a shot. I’ve always found it faster. Docker for Mac worked for some of these tutorials because at the time the projects were small, but I could never get it working well with a large project.

[@batorshikh.baavgaikhuu]

Should I Install rails before the dockerizing rails app.?

[@batorshikh.baavgaikhuu]

I'm getting bundle command not found error.

[@Coderjourney]

+Bat-Orshikh Baavgaikhuu if you run any commands locally, outside of Docker, then you will need it, but you should be able to set everything up without adding more to your development machine. I might have slipped up and forgot to run a command in my container in the video.

[@kojie333]

github link does not work for me ? :)

[@Coderjourney]

+Ryan Clemente whoops, the branch was deleted when my pull request was merged. I've changed the link to be to the pull request itself. Sorry about that.

[@LuisSierra42]

Dat intro

[@Coderjourney]

+Luis Sierra :)

[@Nicholas108108]

Is that a lovely mechanical keyboard I hear in the background?

[@Coderjourney]

+Nuclear Nic Yeah... that's no longer part of my recording set up though.

[@oleingemannk]

Your tutorial is very good, but these things are so complex that you lost me after 4 min ...

[@Coderjourney]

+Ole Ingemann Kjørmo there are quite a few different things to consider and understand. Once you've containerized a few different applications it becomes second nature.

[@oleingemannk]

Thanks. Things are starting to make sense. I think it was the specific gems and services for this app that made it a bit confusing at start.

[@Coderjourney]

+Ole Ingemann Kjørmo Good. This was a bit of an experiment since you normally won't be converting and app that you're unfamiliar with, but I wanted to give a real life example.