# Notes on maintaining/upgrading

## Upgrading texlive.bin

texlive contains a few binaries, defined in bin.nix and released once a year.

In order to reduce closure size for users who just need a few of them, we split it into
packages such as core, core-big, xvdi, etc. This requires making assumptions
about dependencies between the projects that may change between releases; if
you upgrade you may have to do some work here.


## Updating the package set

texlive contains several thousand packages from CTAN, defined in pkgs.nix.

The CTAN mirrors are not version-controlled and continuously moving,
with more than 100 updates per month.

To create a consistent and reproducible package set in nixpkgs, we snapshot CTAN
and generate nix expressions for all packages in texlive at that point.

We mirror CTAN sources of this snapshot on community-operated servers and on IPFS.

To upgrade the package snapshot, follow this process:


### Snapshot sources and texlive package database

Mirror the current CTAN archive to our mirror(s) and IPFS (URLs in `default.nix`).
See <https://tug.org/texlive/acquire-mirror.html> for instructions.


### Upgrade package information from texlive package database


```
$ curl http://mirror.ctan.org/tex-archive/systems/texlive/tlnet/tlpkg/texlive.tlpdb.xz \
           | xzcat | uniq -u | sed -rn -f ./tl2nix.sed > ./pkgs.nix
```

This will download a current snapshot of the CTAN package database `texlive.tlpdb.xz`
and regenerate all of the sha512 hashes for the current upstream distribution in `pkgs.nix`.


### Build packages locally and generate fix hashes

To save disk space and prevent unnecessary rebuilds, texlive packages are built
as fixed-output derivations whose hashes are contained in `fixedHashes.nix`.

Updating the list of fixed hashes requires a local build of *all* packages,
which is a resource-intensive process:


```
# move fixedHashes away, otherwise build will fail on updated packages
$ mv fixedHashes.nix fixedHashes-old.nix
# start with empty fixedHashes
$ echo '{}' > fixedHashes.nix
$ nix-build ../../../../.. -Q --no-out-link -A texlive.scheme-full.pkgs | ./fixHashes.sh > ./fixedHashes-new.nix
# The script wrongly includes the nix store path to `biber`, which is a separate nixpkgs package
$ grep -v -F '/nix/store/' fixedHashes-new.nix > fixedHashes.nix 
```

### Commit changes

Commit the updated `pkgs.nix` and `fixedHashes.nix` to the repository.

