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+#+title: My personal environment sync
+#+description:
+#+keywords: programming
+#+author: Yann Esposito
+#+email: yann@esposito.host
+#+date: [2021-10-30 Sat]
+#+lang: en
+#+options: auto-id:t
+#+startup: showeverything
+
+I have a quite specific system that I improved along the years to manage my
+local environment.
+Think about, binaries I expect to have in my shell, as well as
+configuration files for various utilities, and a few personal scripts.
+
+The notion of what is exactly my local environment is not perfectly defined.
+I expect every of my computers to behave slightly differently.
+Some are for work-only, some personal use only.
+
+For the things I want everywhere, I have a peculiar personal system.
+
+I use a personal script that depends on [[https://yadm.io][yadm]] and [[https://github.com/nix-community/home-manager][home-manager]].
+
+My script try to check if some files where updated and react accordingly:
+
+1. I download the dot-files changes via =yadm=.
+2. If my home-manager files changes, it will run ~home-manager switch~
+   ; if it fails, try to update nix channels then try again.
+3. If my doom emacs packages changed, it will run ~doom sync~
+4. If the script itself changed, it re-run the script after updating itself.
+
+If the script detect that I changed my emacs configuration, it runs ~doom
+sync~ or ~doom sync -u~.
+
+Here it is:
+
+#+begin_src bash
+#!/bin/bash
+
+### logs fn helpers
+
+## colors for tput
+# black=0
+red=1
+green=2
+yellow=3
+blue=4
+# magenta=5
+# cyan=6
+# white=7
+highpr() {
+    printf "$(tput setaf $green)→$(tput sgr0) $(tput bold)%-60s$(tput sgr0)" "$*"
+}
+ok() {
+    local txt="OK"
+    echo -e " [$(tput bold)$(tput setaf $green)${txt}$(tput sgr0)]" >&2
+}
+info() {
+    echo -e " [$(tput bold)$(tput setaf $blue)$*$(tput sgr0)]" >&2
+}
+warn() {
+    echo -e "$(tput bold)$(tput setaf $yellow)$*$(tput sgr0)" >&2
+}
+err() {
+    echo -e "$(tput bold)$(tput setaf $red)$*$(tput sgr0)" >&2
+}
+fail() {
+    err -e "\n[ERR] $*"
+    exit 1
+}
+
+highpr "check nix"
+if ! [ -x "$(command -v nix)" ]; then
+    echo
+    err "nix does not seem to be installed."
+    err "Install it from: https://nixos.org/nix/"
+    exit 1
+fi
+ok
+
+highpr "yadm fetch"
+yadm fetch --quiet  || fail "yadm fetch failed"
+ok
+
+# check the hash of a few files before doing yadm pull
+OLD_SYNC_ENV_ID=$(yadm rev-parse HEAD:bin/sync-env.sh)
+OLD_HOME_MANAGER_ID=$(yadm rev-parse HEAD:.config/nixpkgs/home.nix)
+OLD_DOOM_PACKAGES=$(yadm rev-parse HEAD:.doom.d/packages.el)
+OLD_DOOM_INIT=$(yadm rev-parse HEAD:.doom.d/init.el)
+
+highpr "yadm pull"
+yadm pull --quiet || fail "yadm pull failed"
+ok
+
+# check the hash of a few files after doing yadm pull
+NEW_SYNC_ENV_ID=$(yadm rev-parse HEAD:bin/sync-env.sh)
+NEW_HOME_MANAGER_ID=$(yadm rev-parse HEAD:.config/nixpkgs/home.nix)
+NEW_DOOM_PACKAGES=$(yadm rev-parse HEAD:.doom.d/packages.el)
+NEW_DOOM_INIT=$(yadm rev-parse HEAD:.doom.d/init.el)
+
+highpr "check sync-env diff"
+if ! [ "$OLD_SYNC_ENV_ID" = "$NEW_SYNC_ENV_ID" ]; then
+    warn " changed"
+    warn " Starting ~/bin/sync-env.sh again"
+    echo
+    ~/bin/sync-env.sh
+    exit $?
+fi
+ok
+
+if [ -f "$HOME/.yadm/files.gpg" ]; then
+  highpr "yadm decrypt"
+  yadm decrypt || fail "yadm decrypt failed"
+  ok
+fi
+
+highpr "home-manager"
+USERNAME_NIX_FILE="$HOME/.config/nixpkgs/username.nix"
+if [ ! -f  "$USERNAME_NIX_FILE" ]; then
+  echo "\"$USER\"" >> "$USERNAME_NIX_FILE"
+fi
+if ! [ "$OLD_HOME_MANAGER_ID" = "$NEW_HOME_MANAGER_ID" ]; then
+    echo
+    highpr "home-manager switch"
+    home-manager switch || \
+      ( nix-channel --update && home-manager switch ) || \
+      fail "home-manager switch failed"
+    ok
+else
+    info "skipped"
+fi
+
+highpr "doom-emacs"
+doompath="$HOME/.emacs.d/bin/doom"
+if ! [ "$OLD_DOOM_PACKAGES" = "$NEW_DOOM_PACKAGES" ] || \
+   ! [ "$OLD_DOOM_INIT"     = "$NEW_DOOM_INIT"  ]; then
+  if [[ -x $doompath ]]; then
+      echo
+      highpr "doom sync"
+      $doompath sync || fail "doom failed to sync"
+      ok
+  else
+     fail "Cannot find doom executable at $doompath";
+  fi
+else
+   info "skipped"
+fi
+#+end_src
+
+This is ok
+
+** Bootstrapping
+:PROPERTIES:
+:CUSTOM_ID: boostraping
+:END:
+
+Bootstrapping this system is always a nice problem to think about.
+Once everything is set things are smooths, but to install the system I need
+binaries installed by the system... So... How to handle the dependency
+cycle correctly?
+
+To minimize the pain, I removed more and more bootstrapping dependencies.
+Now my almost single dependence for bootstrapping my environment is =nix=.
+I haven't initialized any machine for a long time now.
+The following should work.
+
+0. Use fish[fn:fish]  ~chsh /bin/fish~
+1. Install nix
+   ~curl -L https://nixos.org/nix/install | sh~
+2. Install home-manager
+   #+begin_src bash
+   nix-channel --add https://github.com/nix-community/home-manager/archive/release-21.05.tar.gz home-manager
+   nix-channel --update
+   export NIX_PATH=$HOME/.nix-defexpr/channels${NIX_PATH:+:}$NIX_PATH
+   nix-shell '<home-manager>' -A install
+   #+end_src
+3. Install and use ~yadm~
+   #+begin_src bash
+   nix-shell -p yadm
+   yadm boostrap
+   yadm remote set-url origin <url-to-my-dot-files-repo>
+   yadm pull
+   #+end_src
+4. Still in the =nix-shell= with =yadm= run ~~/bin/sync-env.sh~
+
+
+There is a risk that step 3 fail because I pin most of my packages in
+home-manager configuration, and it will try to install =yadm=. This can
+conflict with the =yadm= installed in the current =nix-shell=.
+So sometime I need to 1st, remove the line installing =yadm= in my
+home-manager configuration first, then run =home-manager sync= then get out
+of the =nix-shell=, add =yadm= back in the =home-manager= config, then run
+=home-manager sync= again, but this time out of the =nix-shell=.
+And finally I can run my =~/bin/sync-env.sh= command.
+
+[fn:fish] I use fish for interactive shell. I use ~zsh~ for quick dirty
+scripts (a lot better than bash), and I switch to [[https://hackage.haskell.org/package/turtle][turtle]] if I need to be
+serious about the script.