Add postgres setup to mac and linux set up scripts

Summary:
This patch installs postgresql server as part of the overall khan setup
process. To allow our access to the database in our tests and dev
environment, we need to make a couple small tweaks to the default
settings.

In os x land, we need to create a postgres user since the only user
created by homebrew matches the logged in user.

In linux world, we need to relax the authentication requirements to
match the settings that homebrew provides - namely to allow local users
to login with any username.

Note that we create the postgres databases as Makefile step within
webapp (to keep all schema changes to that repo). That forthcoming
change will need to land before this one.

Test Plan:
To test my changes on os x, I uninstalled posgres using homebrew
manually, then ran the steps in `./mac-setup.sh` and verified that they
worked without error.

To test my changes on linux, I booted a blank ubuntu (18.04) container
using docker, with the devtools directory mounted as a volume:
``
docker run -v `/home/dhruv/khan/devtools`:/root/khan/devtools --rm -it
ubuntu
``

I then commented out all steps in `linux_setup.sh` except
`install_postgresql` and ran the following

``
install_postgresql runs
apt-get update
apt-get install -y sudo curl gnupg software-properties-common
cd /root/khan/devtools/khan-dotfiles
./linux-setup.sh
```

Reviewers: benkraft, Kai, csilvers

Reviewed By: Kai, csilvers

Subscribers: kphilip, aric, #classroom-be, csilvers

Differential Revision: https://phabricator.khanacademy.org/D54534

linux-setup.sh

@@ -247,6 +247,24 @@ install_watchman() {
     fi
 }
 
+install_postgresql() {
+    # Instructions taken from
+    # https://pgdash.io/blog/postgres-11-getting-started.html
+    # Postgres 11 is not available in 18.04, so we need to add the pg apt repository.
+    curl -s https://www.postgresql.org/media/keys/ACCC4CF8.asc \
+        | sudo apt-key add -
+
+    sudo add-apt-repository -y "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -c -s`-pgdg main"
+    sudo apt-get update
+    sudo apt-get install -y postgresql-11 postgresql-contrib libpq-dev
+
+    # Set up authentication to allow connections from the postgres user with no
+    # password. This matches the authentication setup that homebrew installs on
+    # a mac. Unlike a mac, we do not need to create a postgres user manually.
+    sudo cp -av postgresql/pg_hba.conf "/etc/postgresql/11/main/pg_hba.conf"
+    sudo service postgresql restart
+}
+
 setup_clock() {
     # This shouldn't be necessary, but it seems it is.
     if ! grep -q 3.ubuntu.pool.ntp.org /etc/ntp.conf; then
@@ -288,5 +306,6 @@ install_protoc
 install_watchman
 setup_clock
 config_inotify
+install_postgresql
 
 trap - EXIT

mac-setup.sh

@@ -281,6 +281,25 @@ install_node() {
     fi
 }
 
+install_postgresql() {
+    if ! brew ls postgresql >/dev/null 2>&1; then
+        info "Installing postgresql\n"
+        brew install postgresql@11
+    else
+        success "postgresql already installed"
+    fi
+
+    # We create a postgres user locally that we use in test and dev.
+    if ! psql \
+      -tc "SELECT rolname from pg_catalog.pg_roles"  postgres \
+      | grep -c 'postgres' > /dev/null 2>&1 ; then
+        info "Creating postgres user for dev\n"
+        psql --quiet -c "CREATE ROLE postgres LOGIN SUPERUSER;" postgres;
+    else
+        success "postgres user already created"
+    fi
+}
+
 install_nginx() {
     info "Checking for nginx\n"
     if ! type nginx >/dev/null 2>&1; then
@@ -343,7 +362,7 @@ install_protoc() {
 }
 
 install_watchman() {
-    if ! which watchman ; then
+    if ! which watchman >/dev/null 2>&1; then
         update "Installing watchman..."
         brew install watchman
     fi
@@ -431,6 +450,7 @@ install_homebrew
 install_slack
 update_git
 install_node
+install_postgresql
 install_nginx
 install_image_utils
 install_helpful_tools

postgresql/pg_hba.conf

@@ -0,0 +1,13 @@
+# We allow any connection by the postgres user to local addresses, without a
+# password.
+
+# TYPE  DATABASE        USER            ADDRESS                 METHOD
+# "local" is for Unix domain socket connections only
+local   all             postgres                              trust
+
+# IPv4 local connections:
+host    all             postgres      127.0.0.1/32            trust
+# IPv6 local connections:
+host    all             postgres      ::1/128                 trust
+
+

setup.sh

@@ -318,6 +318,13 @@ download_db_dump() {
     fi
 }
 
+create_pg_databases() {
+    if [ "$WEBAPP" = true ]; then
+        echo "Creating postgres databases"
+        ( cd "$REPOS_DIR/webapp" ; make pg_create )
+    fi
+}
+
 # Make sure we store userinfo so we can pass appropriately when ka-cloning.
 update_userinfo() {
     echo "Updating your git user info"
@@ -393,6 +400,7 @@ install_deps        # pre-reqs: clone_repos, install_and_setup_gcloud
 install_hooks       # pre-req: clone_repos
 setup_arc           # pre-req: clone_repos
 download_db_dump    # pre-req: install_deps
+create_pg_databases # pre-req: install_deps
 
 
 echo