A post describing my process of getting opam (ocaml package manager) to work on android using termux.

Related issue on dune

Prereqs:

pkg install rsync clang coreutils dash diffutils make nmap-ncat proot

• Install the its-pointless community repo

curl -LO https://its-pointless.github.io/setup-pointless-repo.sh
bash setup-pointless-repo.sh

• Install opam

pkg install opam

I believe the only reason this works is because the creator of that repository wrote a giant patch for the opam build process to work on android. So, it installs a specific version of opam, and I’m not sure if that’s going to change anytime soon.

Then:

unset LD_PRELOAD
termux-chroot
export LD_LIBRARY_PATH=/data/data/com.termux/files/usr/lib
opam init --bypass-checks --disable-sandboxing

That sets up the basic ~/.opam directory (but eventually fails). That prompts you to clean up the broken switch (version), so I said yes.

Then, following the debugging here:

Edit your ~/.opam/config and reduce jobs to 1, and remove the wrap-* lines (that does the sandboxing with bubblewrap, which I couldn’t figure out how to install)

Mine looks like:

opam-version: "2.0"
repositories: "default"
installed-switches: ["5.0.0" "default"]
switch: "5.0.0"
jobs: 1
download-jobs: 3
eval-variables: [
  sys-ocaml-version
  ["ocamlc" "-vnum"]
  "OCaml version present on your system independently of opam, if any"
]
default-compiler: [
  "ocaml-system" {>= "4.02.3"}
  "ocaml-base-compiler"
]

Then, export LDFLAGS="-landroid-shmem" and opam switch create 5.0.0 --jobs=1

A then just wait a while for it to build.

To install dune, after a bunch of troubleshooting and some patches I submitted:

pkg install proot
unset LD_PRELOAD
termux-chroot

git clone --depth=1 https://github.com/ocaml/dune
cd dune

make release
make install PREFIX=$PREFIX

Still not sure if third party deps install properly, I’ve only used it for a dune build with no package dependencies (A little calculator I wrote)