Self-hosting a Gemini capsule

2025-03-30 20:55

TLDR: How I created and serve my Gemini capsule

I've been enjoying reading content in lagrange lately. Lagrange is a client for the Gemini and Gopher protocols, which are essentially simpler versions of HTTP and HTML - text and links only, with gemini providing a little extra styling than gopher. It's a fascinating place. A different kind of reading experience. Posts seem shorter, and written differently. I can't pinpoint what I mean by that, but it's definitely different. In the end it is a very pleasant reading experience.

I'm also super keen to improve my knowledge around networks, servers, self-hosting, and the like, so I thought I'd give a crack at setting up a Gemini capsule hosted on my own "server". I learnt a tonne already, so mission accomplished. Below is how I did it. A reference to myself and anyone else at a beginner level looking to dip their toes into a different area of the web.

First, a bit of background.

I don't have an actual server yet that runs 24/7, so I am just practicing on this laptop (running Linux and Debian), which means the capsule will only be accessible when the laptop is on. I have an unboxed Raspberry Pi 4 (bday present from Dad and R, thanks!), which, if all going well, I will transfer to once up and running.
I bought the zkbro.com domain a while back, and done nothing with it. I have decided to utilise this by using gmi.zkbro.com (gmi as the subdomain). This keeps zkbro.com free for HTTPS if I ever get around to it.
I use the helix text editor to edit files. This uses hx command to load the application. Replace with nano, vim, micro or whatever if something else is used.

Install server molly-brown

I'm using molly-brown as my gemini server software simply because it was available in the apt package manager, and I had tried agate previously without success (though after being through all this rigmarole I might be more successful a second time around).

sudo apt install molly-brown

Configure molly-brown

Create a molly.config file:

hx ~/.config/molly-brown/molly.conf

Enter in the following configurations:

Hostname = "gmi.zkbro.com"
Port = 1965
CertPath = "/home/zkbro/.config/molly-brown/certs/cert.pem"
KeyPath = "/home/zkbro/.config/molly-brown/certs/key.pem"
DocBase = "/home/zkbro/gemini"
AccessLog = "/home/zkbro/.var/log/molly/access.log"
ErrorLog = "/home/zkbro/.var/log/molly/error.log"

Note: Gemini clients by default use port 1965.

Create TLS certificate and key files:

openssl req -x509 -newkey rsa:2048 -keyout ~/.config/molly-brown/certs/key.pem -out ~/.config/molly-brown/certs/cert.pem -days 3650 -nodes -subj "/CN=gmi.zkbro.com"

Resource: How to Create your Own SSL Certificate Authority (CA) for Local HTTPS

Allow ports through firewall

sudo ufw allow 1965/tcp

Set up domain

In my namecheap.com dashboard, go to Domain List --> Manage (zkbro.com) --> Advanced DNS.

Enable Dynamic DNS: true Given I'm using a standard ISP this ensures the IP address I assign to this host are updated dynamically if they ever change (which they do). This also requires a Dynamic DNS client to pass current IP address to namecheap regularly.

Install ddclient:

sudo apt install ddclient

Follow the basic configuration steps in ddclient and when prompted use the password generated back in the namecheap dashboard.

Back in namecheap, under Host Records add a new record with the following information:

Type: A + Dynamic DNS
Host: gmi
Value: My current public IP address
TTL: Automatic

Set modem configurations

Login to the modem GUI in browser at http://192.168.1.1/. Login and password is on the bottom of the modem. I am currently using an old ISP modem (Slingshot) so steps below may look different on different modems.

Set up virtual server: Go to Advanced Setup --> NAT --> Virtual Servers and add a new server with the following configuration:

Use interface: ETH WAN
Custom Service: MollyBrown (or whatever)
Enable LAN Loopback: true (so I can access the site on my own LAN).
Server IP Address: 192.168.1.18 (replace 18 with whatever the server machine is. Check with ip a.)
Status: Enable
External Port Start: 1965
External Port End: 1965
Protocol: TCP
Internal Port Start: 1965
Internal Port Start: 1965

Start server!

molly-brown -c ~/.config/molly-brown/molly.conf

The capsule should now be visible at gemini://gmi.zkbro.com/:

Bonus: Start server on startup

Updated 3/04/2025 after a helpful pointer from Bacardi55. I have been using .desktop files for autostart applications in my ~/.config/autostart/ directory, however systemd.service files appear to be the better option. They provide more options, logging, and work with non-graphical environments, which is great for a server. I found the setup relatively easy too.

First check if a systemd.service file doesn't exist already with the name I'm going to use:

sudo systemctl list-unit-files --type=service

Create .service file:

hx /usr/lib/systemd/system/molly-brown.service

Insert text:

[Unit]
Description=Molly-Brown Startup
Wants=network.target
After=syslog.target network-online.target

[Service]
Type=simple
ExecStart=/usr/bin/molly-brown -c /home/zkbro/.config/molly-brown/molly.conf
Restart=on-failure
RestartSec=10
KillMode=mixed

[Install]
WantedBy=multi-user.target

Check service is created via status:

systemctl status molly-brown.service

Reload systemctl:

sudo systemctl daemon-reload

Enable service:

sudo systemctl enable molly-brown

Reboot to check all working.

Start and stop service by:

sudo systemctl start molly-brown and sudo systemctl stop molly-brown. Disable autostart on reboot with sudo systemctl disable molly-brown.

Conclusion

Well there was A LOT in there. There was a lot of reading involved. Didn't want to do all this willy-nilly. I learnt so much and it was really fun. With the TLS certificate I'm pretty sure everything is honky. Like I said, the capsule won't be accessible if my laptop is off, but in the not too distant future I'll get this up and running on the Raspberry Pi.

I probably need to set up a static IP for my laptop in case it changes and breaks the virtual server setup. I've seen the setting in the modem so shouldn't be a problem.

I have some ideas brewing on some text-only gemlogs, but I want to sit on them for a while as I don't want to have to make decisions on website vs capsule. They're going to need to be very distinct topics.

I need to work on how directories, subdirectories and gmi files are displayed and listed once deployed.

From what I have read, molly-brown is a bit more advanced than agate in that it can handle hosting of other peoples capsules. Now THAT would be cool. I am way off that, but if some of my connections in the blogosphere would be interested in something like this, like a learn-together type project, I'd be totally up for diving into that.

If anyone actually got this far and has some pointers, or if you have a gemini capsule or gopherhole! (I'd love to follow along) please email me.