App Submission: Fulcrum

[sahilph]

App Submission

App name

Fulcrum

Closes #613, also possibly resolves #134

For those who want to try it now, Fulcrum is also available on my personal app store

256x256 SVG icon

https://svgshare.com/i/1Acv.svg

Gallery images

1.jpg:

2.jpg:

3.jpg:

4.jpg:

I have tested my app on:

• umbrelOS on a Raspberry Pi
• umbrelOS on an Umbrel Home
• umbrelOS on Linux VM

[sahilph]

Regarding app IPs in exports.sh, is there any logic to set the IPs ?

Currently I have just selected them randomly so as to not conflict with existing Electrs.

[github-actions]

⚠️   Linting finished with 1 warning   ⚠️

Thank you for your submission! This is an automated linter that checks for common issues in pull requests to the Umbrel App Store.

Please review the linting results below and make any necessary changes to your submission.

Linting Results

Severity	File	Description
ℹ️	fulcrum/docker-compose.yml	Mounted file/directory "/fulcrum/torrc" doesn't exist: The volume "${APP_DATA_DIR}/torrc:/etc/tor/torrc:ro" tries to mount the file/directory "/fulcrum/torrc", but it is not present. This can lead to permission errors!
ℹ️	fulcrum/docker-compose.yml	External port mapping "${APP_FULCRUM_NODE_PORT}:${APP_FULCRUM_NODE_PORT}": Port mappings may be unnecessary for the app to function correctly. Docker's internal DNS resolves container names to IP addresses within the same network. External access to the web interface is handled by the app_proxy container. Port mappings are only needed if external access is required to a port not proxied by the app_proxy, or if an app needs to expose multiple ports for its functionality (e.g., DHCP, DNS, P2P, etc.).
ℹ️	fulcrum/docker-compose.yml	Potentially using unsafe user in service "app": The default container user "root" can lead to security vulnerabilities. If you are using the root user, please try to specify a different user (e.g. "1000:1000") in the compose file or try to set the UID/PUID and GID/PGID environment variables to 1000.
⚠️	fulcrum/umbrel-app.yml	"icon" and "gallery" needs to be empty for new app submissions: The "icon" and "gallery" fields must be empty for new app submissions as it is being created by the Umbrel team.

Legend

Symbol	Description
❌	Error: This must be resolved before this PR can be merged.
⚠️	Warning: This is highly encouraged to be resolved, but is not strictly mandatory.
ℹ️	Info: This is just for your information.

[nmfretz]

Thanks for submitting Fulcrum @sahilph!

We've got our heads down on some other aspects of the codebase, but we have this on our radar and will get to it soon.

One quick thought (as a reminder to myself when I come back to this) is that since this is essentially a drop-in replacement for Electrs, we may want to wait until we've implemented a way to choose which app you want to use for a certain protocol (e.g., the electrum protocol). This is on our roadmap. This would allow users to switch to whatever Electrum implementation they want and have it work with all their other bitcoin ecosystem apps that rely on Electrum.

Right now, if we bring Fulcrum to the app store, apps like Mempool, BTC RPC Explorer, etc. that depend on an electrum server would not be able to use Fulcrum. Maybe this is okay for now.

[sahilph]

apps like Mempool, BTC RPC Explorer, etc. that depend on an electrum server would not be able to use Fulcrum.. Maybe this is okay for now.

@nmfretz Yes, right. Initially I had set the export variables names to be same as that of Electrs, so that they will be able to use Fulcrum directly, but then I saw the Bitcoin Knots Submission #953, and changed the variables names and also added a note that Fulcrum will be integrated later on, very similar to how it was done for Knots.