So I have been browsing the web for a while now and can't seem to find an answer on how to build the native DocC Xcode documentation using a CLI command.
Both the xcodebuild commands and Fastlane do not provide a command to build the documentation - as far as I know.
The docs are supposed to be built inside a CI/CD Github Actions workflow. If there are other methods to accomplish this, any help is appreciated.
Apple has added a new command to xcodebuild tools:
xcodebuild docbuild
You can also take a look at the WWDC presentation "Host and automate your DocC documentation". Start watching from 7:06 min onwards for DocC automation: https://developer.apple.com/videos/play/wwdc2021/10236/
To complement the initial answer, I'd like to mention this complete summary of all the WWDC21 videos regarding DocC that contains precious information about automation.
Indeed, there's a feature in Xcode 13 for building documentation through the command line that includes the docbuild action with many possible options as described below.
Besides, Xcode 14 fosters the DocC archive content deployment at the root of a web server thanks to its new compatibility with most web servers.
Even if a solution has already been provided by @Colin , I deemed it important to append some information that may be crucial for some.
I tweaked the xcodebuild docbuild for modular projects as below:
xcodebuild -project ModularSlothCreator.xcodeproj -derivedDataPath docsData -scheme ModularSlothCreator -destination 'platform=iOS Simulator,name=iPhone 13 Pro Max' -parallelizeTargets docbuild
I also tweaked the docc site generation using the transform-for-static-hosting flag:
$(xcrun --find docc) process-archive transform-for-static-hosting "$ARCHIVE" --hosting-base-path ModularSlothCreator/$ARCHIVE_NAME --output-path docs/$ARCHIVE_NAME
I've updated the original demo showcased at WWDC with support for static hosting of modular App targets (rather than only supporting a single Swift Package announced at WWDC) using GitHub Pages without needing to define a server configuration for convenience in my blog post.