Leveraging Central And Local Package Repositories For Latex
The Package Management Problem
Finding and installing the correct LaTeX packages and versions to build documents can be challenging for LaTeX users. Package dependencies, where one package requires additional packages to function properly, can compound installation problems. Conflicts frequently arise when multiple installed packages require incompatible versions of the same dependencies, resulting in frustration for LaTeX authors.
LaTeX distributions provide varying degrees of package management to obtain and configure packages from official distribution-maintained repositories. However, the narrow scope of many distribution repositories poses further difficulties discovering new packages from the vastly broader selection available in the wider LaTeX ecosystem.
Installing Packages Locally
Most LaTeX distributions integrate package managers to query and install available packages from distribution-managed repositories. For example, TeX Live utilizes the tlmgr utility for fetching, installing, upgrading and removing TeX Live packages, while MiKTeX includes a graphical user interface package manager for handling repositories.
Creating local TeX package trees provides an alternate method of centralized package management. After defining a root folder location, new subfolders can be added to mimic standard TeX directory hierarchies within. Placing package files manually within the appropriate local tree folders keeps packages neatly organized and available to documents.
Maintaining an informal local package repository in a similar central parent folder using a simplified structure, with just package files and text listing dependencies, provides scalable centralized package management. Callable scripts can then parse local folders and repositories to automatically fetch and install current package versions into documents as needed.
Using CTAN as a Central Repository
The Comprehensive TeX Archive Network, or CTAN, offers public repositories containing almost all known free LaTeX related packages - currently over 8,000 packages across TeX, LaTeX, Metafont and many other formats. The CTAN website provides keyword search functionality across the entire archive.
The CTAN website allows manual exploration and downloading of individual package files hosted at universities worldwide. Automating this process instead by calling the CTAN services via custom scripts facilitates regular checks for fetching updated versions of packages used locally. Scripted CTAN queries also enable batch-fetching multiple packages in one step.
Creating two-way integration between local and central repositories keeps local packages continually updated against CTAN. Scripts can run daily/weekly checks of CTAN for updated versions of all locally stored copies of files. Automated overwriting of outdated local packages from fresh downloads keeps documents using current package releases minimizing errors.
Custom Package Repositories
Teams and organizations can create internal custom LaTeX package repositories tailored specifically to group documentation needs. Building upon the structure of local package management trees, a centralized internal repository offers standardized packages compliant with institutional policies and formats.
Custom repositories provide options to contribute new or modified packages back to the CTAN archive, to expand available packages benefiting worldwide TeX users. All CTAN contributions undergo review processes, based on established packaging standards, prior to acceptance and integration.
Public GitHub repositories present alternate hosting opportunities to conveniently share packages publicly or privately with other developers and groups. Easy GitHub integration with continuous integration platforms like Travis CI also assists package contributors in implementing best practices like tests and validation.
Troubleshooting Package Installations
Diagnosing LaTeX document build failures from missing packages first requires checking all used packages are installed locally as expected. Confirming locations in either distribution repositories, local trees or secondary custom repositories accounts for variability in potential storage locations.
Dependency conflicts from incompatible package versions arise commonly during installations. Tracing conflicts back to the specific packages requiring contradictory dependency versions enables troubleshooting. Targeted version pinning in scripts provides control over package versions fetched into local repositories, especially when pulling updates automatically from CTAN.
Maintaining multiple independent local package repositories and associated TeX trees in parallel facilitates conflict management. Isolating groups of interdependent packages into separate trees avoids cross-repository contamination between coexisting incompatible packages. Such separation empowers using multiple package versions in parallel documents.
