Serve multiple Django sites from one cloud server

I was a long time user of Heroku, but after they announced the removal of all of their free plans, I have started to look to move all of my side projects to other hosts. I don't begrudge them for wanting to focus on paying customers, but most of my side projects have very low traffic so their pricing tiers don't make much sense for me anymore.

Initially I moved most of my sites to render. It is a delightful hosting platform very similar to Heroku, although you'll need to translate any custom buildpacks into the render.yml file, so it's not quite as simple a translation as I would like. However, render is easy to use and has a nice UI to provision services. I still have a few sites hosted there, mostly for their managed Postgres database support. I even have a checklist I use to deploy sites to render.

However, for low traffic sites I have increasingly become enamored with CapRover after Tobi-De suggested it to me. CapRover can be hosted on lots of hosting platforms, but I have primarily used it on Digital Ocean. If you sign up for Digital Ocean you will get $200 in free credits (and full disclosure, I get a little credit for my hosting costs as well).

Self-hosting CapRover

Benefits

One major pro of using CapRover is that you can use one server to host multiple sites at once. On Heroku or render each "service" will host one site by default. Free tiers will typically limit you to one free site, even for very low traffic sites. Sometimes services in the free tier will be "put to sleep" as well. On CapRover, I can host multiple Django apps on a $6/month server and they are fast and reliable.

Another pro is that CapRover has a long list of one-click installs for open source software. This includes backend services like Postgres, mysql, and redis. Complete packages are also available like analytics tracking (umami and ackee), error monitoring (glitchtip), or uptime monitoring (Uptime Kuma) are all one click away.

Drawbacks

The major con is that support is mainly through GitHub Issues. However, the CapRover documentation is pretty good -- I did have to re-read some sections a few times to understand what to do, but overall it seems pretty solid. However, hopefully this tutorial lets you avoid some of the learning curve I went through.

One other con is that I have noticed a short time where my sites are unavailable while new code is getting deployed. According to this comment CapRover does support zero-downtime deploys. For low traffic sites I'm not worried about a few seconds of downtime, but it is something to keep in mind.

Other options

dokku is another popular option for a self-hosted PaaS and is similar to CapRover, but it doesn't have an admin web UI. It does support buildpacks so if you are transferring from Heroku that might be helpful.

How to create a server in the ☁️

Sign up

There are lots of options for servers in the cloud, however the easiest one I have used with CapRover is Digital Ocean. Sign up for an account to get started.

Create a project

A project holds related servers together. To make things easier, I just have one project that I put everything in.

Create a server

Digital Ocean calls their cloud servers droplets (which is sort of adorable come to think of it).

1. Click the green Create button in the top navigation header
2. Click Droplets
3. Under Choose an image, click the Marketplace tab
4. Search for "caprover" in the Search keyword text box
5. Click CapRover in the search results that shows up
6. Under Choose a plan, click Basic
7. In the CPU options radio button, click Regular with SSD
8. Click the $6/mo option; feel free to choose a more expensive option if you want -- you will be able to change this option later on if you want
9. Under Chose a datacenter region, select a region close to you; I selected New York
10. Under Authentication, create an SSH key with ssh-keygen or 1Password and copy the output of the public key in
11. Click the Monitoring checkbox under Select additional options
12. Put in a memorable name for your new server in the cloud in the text box under Choose a hostname
13. Click Create Droplet

It might take a few minutes, but eventually there will be an ipv4 address on the droplet page. With that you can start setting up CapRover.

At this point, you can access CapRover by going to droplet IP address and a port of 3000, e.g. if your IP address was 123.456.789.123, then you could go to 123.456.789.123:3000. The default login is "captain42", but I suggest continuing on. The CapRover setup will prompt you to change the password in the next step.

CapRover setup

Subdomain

You can use any domain name for the CapRover instance. It doesn't need to be the site that you want CapRover to host. For example, let's say you have two domains, boats-r-us.com and boats-and-totes.com. Both will be Django projects that are deployed using CapRover. You could use either of those domains for the CapRover admin UI or another domain. For example, you might want to host CapRover on boat-lovers.com. It's up to you to decide for your situation.

You can do this in any DNS provider, but I tend to use Cloudflare. Other DNS providers should be a similar process.

1. Log into Cloudflare
2. Click on the domain name you want to use for the CapRover admin UI, e.g. boat-lovers.com
3. Click on DNS in the sidebar
4. Click on Add record
5. Make sure that Type is "A"
6. Decide on a unique subdomain which will be the third-level domain where all CapRover services will be created -- this will require a wildcard fourth-level A name to be added; e.g. apps could be your third-level domain name for boat-lovers.com so an app named boats-r-us would live at boats-r-us.apps.boat-lovers.com a. Add the subdomain with the fourth-level wildcard to the Name text box; e.g. "*.apps"
7. Put the ipv4 address for the droplet into the IPv4 address text box
8. Make sure the the Proxy status is un-checked, i.e. it is grey and says DNS only
9. Click Save

Server setup

Run the following in your source code directory on your local machine.

1. npm install -g caprover
2. caprover serversetup
3. Follow the prompts, but make sure to use the third-level domain for your "root domain", e.g. apps.boat-lovers.com
4. Go to captain.apps.boat-lovers.com and login with the password you set to access the CapRover admin UI

Deploy Django code

My docker-python-poetry-django repository has the files needed for CapRover to work correctly.

• captain-definition: tells CapRover where to find the Dockerfile
• Dockerfile: multi-stage definition for how the server should be setup to run the Django site; it installs dependencies via poetry, runs the bin/post_compile script for Django-specific management commands, and serves the site via gunicorn
• bin/post_compile: script to run collectstatic, migrate, etc.; can be customized for your particular application

Make sure to update ALLOWED_HOSTS in your Django settings file to include the correct fourth-level domain name, e.g. ALLOWED_HOSTS = ['boats-r-us.apps.boat-lovers.com'].

1. caprover deploy from source code directory and follow the prompts
2. Go the the CapRover admin UI and click on Apps and then your app name
3. Click on the Deployment tab at the top
4. Click on View Build Logs if necessary and watch for errors
5. Go to your app's URL via the fourth-level domain name

Public domain name setup

Now that your app works, you can provide a better public URL for people to access the site. A "naked" domain won't have a "www" in front of it. You can also create a rule in Cloudflare to redirect one type of domain to the other.

first-level domain name

The first level domain can be either "naked" or a third-level domain name. A "naked" domain only has a first level domain name and a TLD, e.g. boat-lovers.com.

Naked

This will alias boat-lovers.com to boats-r-us.apps.boat-lovers.com.

1. Log into Cloudflare
2. Click on the domain name you want to use, e.g. boat-lovers.com
3. Click on DNS in the sidebar
4. Click on Add record
5. Make sure that Type is "A"
6. Put "@" in for the Name
7. Put the droplet ipv4 address into the IPv4 address text box
8. Make sure the the Proxy status is checked
9. Click Save

www

This will alias www.boat-lovers.com to boats-r-us.apps.boat-lovers.com.

1. Log into Cloudflare
2. Click on the domain name you want to use, e.g. boat-lovers.com
3. Click on DNS in the sidebar
4. Click on Add record
5. Make sure that Type is "CNAME"
6. Put "www" in for the Name
7. Put the app's URL into the Target text box
8. Make sure the the Proxy status is checked
9. Click Save

Add the domain name

1. Log into your CapRover instance, e.g. captain.apps.boat-lovers.com
2. Click on Apps in the sidebar
3. Click on the name of your app in the list
4. In the HTTP Settings tab, underneath of Your app is publicly available at:, add either the naked domain or the "www" domain (or both), e.g. boats-r-us.com or www.boats-r-us.com
5. Click Connect New Domain
6. Once all domains are added, click Enable HTTPS for each one (even though this seems unnecessary since Cloudflare provides free SSL as well)

Automatic deploys after pushing to GitHub

Once manual deploys are working, you can set up CapRover to deploy a new version of your code every time you push to a specific branch in your repository.

Generate the keys for deploys

Generate a private key and public key in the same directory as your code.

ssh-keygen -t ed25519 -C "skiff@boat-lovers.com" -f ./deploykey -q -N ""

A private key (named deploykey) and a public key (deploykey.pub) will be created in the current directory.

Add the public key to GitHub

1. Create a deploy key in GitHub by going to https://github.com/USERNAME/REPOSITORY_NAME/settings/keys/new
2. Give the key a Title (e.g. "CapRover")
3. Paste the contents of deploykey.pub into the Key text field
4. Do not check Allow write access unless you have a good reason to
5. Click Add key

Add the private key to CapRover

Go to the Deployment tab for your app in CapRover. Scroll down to Method 3: Deploy from Github/Bitbucket/Gitlab.

1. Type your GitHub repo into Repository
2. Put the branch you want to automatically deploy into Branch (typically either "main" or "master")
3. Paste the contents of the deploykey file into the text field underneath of Or, instead of username/password, use SSH Key:
4. Make sure there is a blank line at the bottom of the pasted contents otherwise GitHub won't validate it
5. Click Save & Update
6. The text box above Repository should now have a long URL inside of it; copy that into your clipboard

Add the webhook to GitHub

1. Go to https://github.com/USERNAME/REPOSITORY/settings/hooks/new and paste the generated URL from the last step into the Payload URL text box; leave the rest of the settings as-is
2. Click Add webhook

Now when you push commits to the branch you specified:

1. GitHub calls the webhook
2. CapRover pulls the new code from GitHub
3. CapRover builds the Dockerfile
4. CapRover deploys the site

Custom Dockerfile per app

For one of my side projects, devmarks.io, there is a web site and a worker process. They share the same code. So, I have two apps in CapRover. One named devmarks-web and one named devmarks-worker. Typically my Dockerfile calls a script that runs collectstatic and a few other management commands and then runs gunicorn. However, for my worker app I don't need collectstatic to run and instead of gunicorn I would like to start my worker process.

CapRover allows per-app changes to the captain-definition file. So, for devmarks-worker I created a captain-definition-worker file that references a new Dockerfile-worker file. The only difference in Dockerfile-worker is the CMD statement at the end which calls python manage.py worker.

1. Go to your app in the CapRover admin UI
2. Click the Deployment tab
3. Scroll to the bottom to the captain-definition Relative Path textbox
4. Click Edit
5. Type in ./captain-definition-worker and click Save & Update

Now when CapRover starts up the container it will use captain-definition-worker and Dockerfile-worker to start up my worker process.

Cron jobs

I have a few cron jobs that I need to run that are currently Django management commands. I spent a while researching how to run these cron jobs in Docker, but kept getting turned around when thinking about them.

Cron + Docker = The Easiest Job Scheduler You’ll Ever Create seems useful if your cron jobs are independent of your code. Chadburn is a one-click install for CapRover and seemingly helps manage cron tasks, but has the same limitations since it is contained with its own container. However, my cron jobs need to either 1) be in the same Docker instance as my code, or 2) be able to call into the Docker container with my code.

Setting up cron inside my Docker container with my source code would mean that every instance would run the cron jobs, potentially duplicating the cron jobs when more than one instance of my app was running. That didn't seem ideal.

The option I am leaning toward is to specify the cron jobs in the droplet that contains all of my containers. It feels a little messy, but I will document them in my code repository to try to mitigate that. This solution works because from the droplet I can call into any CapRover app I want.

docker exec -it $(docker ps --filter name=srv-captain--APP_NAME -q) python manage.py MANAGEMENT_COMMAND

Troubleshooting CapRover

At one point, I broke the CapRover admin UI because of an SSL issue. I ended up looking through the logs and restarting the CapRover instance to fix it.

Logging into the droplet

Log into Digital Ocean and click the Console button for your droplet.

View logs

docker service logs srv-captain--APP_NAME --since 60m --follow

Restart CapRover

docker service update captain-captain --force

See all running apps

docker ps

Run Django management command

Get the Docker container id from the ps command above and use it with docker exec.

docker exec -it CONTAINER_ID python manage.py MANAGEMENT_COMMAND

Or to run a command by the CapRover app name.

docker exec -it $(docker ps --filter name=srv-captain--APP_NAME -q) python manage.py MANAGEMENT_COMMAND

Domain Verification Failed - Error 1107

Enabling HTTPS for a domain is usually painless, but one time I kept getting a validation error for an extended period. I double-checked that the new IP and domain were set properly in Cloudflare multiple times and waited a few hours, but it never worked. However, you can skip domain verification if needed.

1. Log into Digital Ocean
2. Go to your droplet
3. Click on the Console button
4. Copy the following into the terminal and pretty Enter

echo  "{\"skipVerifyingDomains\":\"true\"}" >  /captain/data/config-override.json
docker service update captain-captain --force

5. Wait a few minutes for CapRover to restart 6. Try to enable HTTPS for your app again and hopefully it will work

Conclusion

Hopefully this has been helpful for anyone who wants to host a Django site (or a few!) relatively inexpensively. Just a reminder if you sign up for Digital Ocean with my referral code you will get $200 in free credits (and my undying appreciation!).

More resources, documentation, and details

• CapRover documentation
• CapRover service override
• bash strict mode
• Docker setup by Tobi-De
• Docker multi-staged builds by michaeloliverx
• Explanation of Docker by Tiangolo
• More information about GitHub deploy keys
• How to Deploy Django using CapRover
• The Essential Django Deployment Guide

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Hi, I'm Adam 👋

I've been a backend programmer for ~20 years in a variety of different languages before I discovered Python 10 years ago and never looked back. alldjango includes all the hard-won experience I've gained over the years building production-scale Django websites.

Feel free to reach out to me on Mastodon or make a GitHub Issue with questions, comments, or bitter invectives.

All code is licensed as MIT.