Uninstall node@16, upgrade node@20 and postgresql@14 on mac (#117)

## Summary:
The presence of the node@16 homebrew formula has undesirable effects
when installing postgresql@14 due to a mismatch in shared dependencies.
By removing node@16 before installing node@20 and postgresql@14,
homebrew is free to update all dependencies to latest.

Some users already have a functional node@20 brew install but are on an
older non-functional postgresql@14 due to us previously forcing
compatibility with the deprecated node@16. Fully embrace the fact that
the homebrew team only ever tests the latest formula against all other
latest formulas and upgrade node@20 and postgresql@14 if they're out of
date.

Issue: none

Test plan:

Replicate node@16 state:

```sh
brew uninstall node@16
brew uninstall node@20
brew uninstall postgresql@14

brew install node@16
brew link --force --overwrite node@16

wget -O /tmp/icu4c.rb https://raw.githubusercontent.com/Homebrew/homebrew-core/74261226614d00a324f31e2936b88e7b73519942/Formula/i/icu4c.rb
HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 brew reinstall /tmp/icu4c.rb --force --skip-cask-deps

wget -O /tmp/[email protected] https://raw.githubusercontent.com/Homebrew/homebrew-core/521c3b3f579cd4df16e0b85b26a49e47d2daf9c6/Formula/p/[email protected]
brew install /tmp/[email protected]
HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 brew reinstall /tmp/icu4c.rb --force --skip-cask-deps
```

Test node@16 setup:

```sh
brew ls --version postgresql@14
psql -tc "SELECT rolname from pg_catalog.pg_roles" postgres
node -v
```

Test khan-dotfiles upgrade to node@20 and latest postgresql@14:

```sh
make

psql -tc "SELECT rolname from pg_catalog.pg_roles" postgres
node -v
```

In webapp, verify local dev:

```sh
make deps
make serve
```

Author: nathanjd

Reviewers: MrNickBreen, csilvers, nathanjd, aag, somewhatabstract

Required Reviewers:

Approved By: MrNickBreen, csilvers

Checks:

Pull Request URL: #117

bin/mac-setup-postgres.py

@@ -13,8 +13,6 @@
 # may be useful to use homebrew to install python3 before running python3
 # scripts.
 
-# TODO(ericbrown): Why do we support anything other than postgresql@14 ?
-
 import os
 import re
 import subprocess
@@ -38,13 +36,6 @@ def get_brewname():
     if result.returncode == 0:
         return POSTGRES_FORMULA
 
-    # TODO(ericbrown): Remove when sure this is no longer needed
-    # I believe this code is from when postgresql 11 was the current version
-    result = subprocess.run([BREW, 'ls', 'postgres', '--versions'],
-                            capture_output=True, text=True)
-    if result.returncode == 0 and re.search(r'\s11\.\d', result.stdout):
-        return "postgresql"
-
     # There is no postgresql installed
     return None
 
@@ -71,8 +62,8 @@ def link_postgres_if_needed(brewname, force=False):
 
 
 def install_postgres() -> None:
-    subprocess.run(['BREW', 'install', 'postgresql@14'], check=True)
-    link_postgres_if_needed('postgresql@14', force=True)
+    subprocess.run(['BREW', 'install', POSTGRES_FORMULA], check=True)
+    link_postgres_if_needed(POSTGRES_FORMULA, force=True)
 
 
 def is_postgres_running(brewname: str) -> bool:
@@ -116,6 +107,19 @@ def setup_postgres() -> None:
         brewname = POSTGRES_FORMULA
         install_postgres()
     else:
+        # The homebrew team only tests the latest versions of every package
+        # together so make sure we're on latest.
+        print(f'{SCRIPT}: {BREW} upgrade {brewname}')
+        result = subprocess.check_output([BREW, 'upgrade', POSTGRES_FORMULA])
+
+        # Initiate and wait for restart if an upgrade happened. Otherwise the
+        # service won't be ready in time for does_postgres_user_exist().
+        if (re.search(r'Upgrading \d+ outdated package',
+                      result.decode('utf-8'))):
+            print(f'{SCRIPT}: {BREW} services restart {brewname}')
+            subprocess.check_call([BREW, 'services', 'restart',
+                                   POSTGRES_FORMULA])
+
         # Sometimes postgresql gets unlinked if dev is tweaking their env
         # Force in case user has another version of postgresql installed too
         link_postgres_if_needed(brewname, force=True)

mac-setup-normal.sh

@@ -39,11 +39,10 @@ trap exit_warning EXIT   # from shared-functions.sh
 
 
 update_path() {
-    # We need /usr/local/bin to come before /usr/bin on the path, to
-    # pick up brew files we install.  To do this, we just source
-    # .profile.khan, which does this for us (and the new user).
-    # (This assumes you're running mac-setup.sh from the khan-dotfiles
-    # directory.)
+    # We need /opt/homebrew/bin (/usr/local/bin on x86) to come before /usr/bin
+    # on the path, to pick up brew files we install.  To do this, we just source
+    # .profile.khan, which does this for us (and the new user). (This assumes
+    # you're running mac-setup.sh from the khan-dotfiles directory.)
     . .profile.khan
 }
 
@@ -153,22 +152,55 @@ update_git() {
     fi
 }
 
+# install_or_upgrade_brew_formula ensures the latest version of the passed
+# formula is installed as the homebrew team only tests the latest versions of
+# every formula together.
+install_or_upgrade_brew_formula() {
+    formulaName=$1
+
+    if brew ls --versions "$formulaName" >/dev/null ; then
+        info "Upgrading brew formula $formulaName\n"
+        brew upgrade "$formulaName"
+    else
+        info "Installing brew formula $formulaName\n"
+        brew install "$formulaName"
+    fi
+}
+
 install_node() {
+    # We need to uninstall the deprecated node@16 homebrew formula if it is
+    # installed so its dependencies don't conflict with the dependencies of the
+    # latest postgresql@14 homebrew formula.
+    if brew ls --versions node@16 >/dev/null ; then
+        brew uninstall node@16
+    fi
+
+    # Upgrade brew-installed node@20 if it is already installed.
+    if brew ls --versions node@20 >/dev/null ; then
+        install_or_upgrade_brew_formula node@20
+    fi
+
+    # Install node@20 homebrew formula if no node binary is found in $PATH.
     if ! which node >/dev/null 2>&1; then
         # Install node 20: It's LTS and the latest version supported on
         # appengine standard.
-        brew install node@20
+        install_or_upgrade_brew_formula node@20
 
-        # We need this because brew doesn't link /usr/local/bin/node
-        # by default when installing non-latest node.
+        # We need this because brew doesn't link /opt/homebrew/bin/node
+        # (/usr/local/bin/node on x86) by default when installing non-latest
+        # node.
         brew link --force --overwrite node@20
     fi
+
+    # At this point, users should have a node binary, whether it's from homebrew
+    # (preferred), NVM or standard install.
+
     # We don't want to force usage of node v20, but we want to make clear we
     # don't support anything else.
     if ! node --version | grep "v20" >/dev/null ; then
         notice "Your version of node is $(node --version). We currently only support v20."
         if brew ls --versions node@20 >/dev/null ; then
-            notice "You do however have node 20 installed."
+            notice "You do however have node 20 installed via brew."
             notice "Consider running:"
         else
             notice "Consider running:"
@@ -284,7 +316,7 @@ install_python_tools() {
         info "Installing python 3.11\n"
         brew install [email protected]
     fi
-    # The python3 cask does not install `python` as a symlink, so we do.
+    # The python3 formula does not install `python` as a symlink, so we do.
     if ! [ -e /usr/local/bin/python ]; then
         ln -snf python3 /usr/local/bin/python
     fi