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Posted on 2021-04-04
Based on my previous post about managing a local docker registry[1], as promised let's use it to create a useful image and deploy it on my swarm cluster homelab[2].
2: https://bacardi55.io/pages/home-lab/
For this example, I've decided to use the latest image I've created: gmnisrv[3].
3: https://git.sr.ht/~sircmpwn/gmnisrv
Wait what? Gmnisrv running on a docker swarm? Why??
There are no real good reason to have the gemini server as a docker service… So why? Well the real reasons? Because:
Last week, I made the change from the local installation on a test pi to the cluster, smoothly from what I've seen, without certificate change. But that's not the point of this article^^ (and TBH, I failed[^1] the weekend before :D).
So first thing first, we need to create the image on the registry before being able to use it on the cluster. Feel free to refer to my post about managing a local docker registry[4].
On the registry (in my case named freeza), let's create the image. Let's create a working directory:
mkdir ~/dockerfiles/gmnisrv && cd ~/dockerfiles/gmnisrv
Then, create the very simple Dockerfile:
FROM alpine:3.12
RUN apk add --no-cache git make scdoc openssl-dev build-base mailcap && \
cd /tmp && \
git clone https://git.sr.ht/~sircmpwn/gmnisrv && \
cd gmnisrv && \
mkdir build && \
cd build && \
../configure --prefix=/usr && \
make && \
make install
VOLUME /certs
VOLUME /config
VOLUME /data
CMD ["gmnisrv", "-C", "/config/gmnisrv.ini"]
Very simple :-).
Then, let's try and build the image:
docker build .
If this works correctly, you can tag the image (I always prefix their name with b55-):
docker build . -t registry.local:5000/b55-gmnisrv:latest
Adapt with your registry hostname and port.
Push the image to the directory:
docker push registry.local:5000/b55-gmnisrv:latest
To test the image, you can either use docker run or docker-compose. Because I'm will use a docker-compose file on my cluster, I prefer testing it with a docker-compose file, buit this doesn't matter.
In my case, the local docker-compose.yml file is:
version: '3'
services:
gmnisrv:
image: registry.local:5000/b55-gmnisrv:latest
ports:
- 1965:1965
volumes:
- /path/to/testdir/gmnisrv/data/:/data
- /path/to/testdir/gmnisrv/config/:/config
- /path/to/testdir/gmnisrv/certs:/certs
Then the usual docker-compose up to see if this works correctly (be sure to create the volumes if you want to try with it).
If you want to run a full test before deploying on your cluster, you can create a simple .gmi file in the /data/ directory, create a dev host in the gmnisrv config file (and edit your host file).
If everything work, we can use it on the cluster. Adapt a bit the docker file to have:
version: '3'
services:
server:
image: registry.local:5000/b55-gmnisrv:latest
ports:
- "1965:1965"
deploy:
placement:
constraints:
- node.hostname == ptitcell2
volumes:
- /path/to/containers-data/gmnisrv/data/:/data
- /path/to/containers-data/gmnisrv/certs/:/certs
- /path/to/services-config/gmnisrv/config/:/config
Main difference the placement constraints to a specific node of the cluster. I could have use traefik[5] for load balancing the entry like I do for all services… But I didn't^^. I didn't see the point of adding load to traefik and the node manager for gmnisrv that works on a port that will only be used by gmnisrv. Gmnisrv support multi hosts anyway if I want to add capsules in the future (I'm planing to have a feed type of capsule).
5: https://traefik.io/traefik/
So, long story short, I force the container to only work on the ptitcell2 node. And I forward the 1965 port on my router to the ptitcell2 node. I thus save a bit on the manager.
If you don't care by recreating new certs (if your capsule wasn't live yet), you can just start it like this, otherwise just copy/paste the certificates in the right folder before starting the stack with docker stack deploy gmnisrv -c /path/to/services-config/gmnisrv/docker-compose.yml.
And voilà :] Granted that I have close to no reader on my capsule, I can still say it has worked perfectly since then!
[^1]: In reality I failed for multiple reasons, but also discovered a bug in the latest version of gmnisrv. I fixed it with the help of Drew Devault[6]. Since then my patch has been accepted so even if what I wrote was the simplest patch[7] in the history of patch, I'm still happy about it^^.
7: https://git.sr.ht/~sircmpwn/gmnisrv/commit/8b65e303b01fc573cb1c40a365fb5db166146a37