install: Re-order final steps.

Move database creation to immediately before database initialization;
this means it happens in a directory readable by the `zulip` user, as
well as placing it alongside similar operations.  It removes the check
for the `zulip::postgresql_common` Puppet class; instead it keeps the
check for `--no-init-db`, and switches to require
`zulip::app_frontend_base`.  This is a behavior change for any install
of `zulip::postgresql_common`-only classes, but that is not a common
form -- and such installs likely already pass `--no-init-db` because
they are warm spare replicas.

As a result, all non-`zulip::app_frontend_base` installs now skip
database initialization, even without `--no-init-db`.  This is clearly
correct for, e.g. Redis-only hosts, and makes clearer that the
frontend, not the database host, is responsible for database
initialization.

scripts/lib/install

@@ -499,11 +499,30 @@ EOF
     fi
 fi
 
-if has_class "zulip::postgresql_common" && [ -z "$NO_INIT_DB" ]; then
+# Set up a basic .gitconfig for the 'zulip' user
-    "$ZULIP_PATH"/scripts/setup/create-database
+if [ -n "$ZULIP_ADMINISTRATOR" ]; then
+    (
+        cd / # Make sure the current working directory is readable by zulip
+        su zulip -c "git config --global user.email $ZULIP_ADMINISTRATOR"
+        su zulip -c "git config --global user.name 'Zulip Server ($EXTERNAL_HOST)'"
+    )
 fi
 
-if has_class "zulip::app_frontend_base"; then
+if ! has_class "zulip::app_frontend_base"; then
+    set +x
+    cat <<EOF
+
+Success!
+
+Not configuring PostgreSQL, or /home/zulip/deployments, because this
+is not a front-end install.
+
+EOF
+    exit 0
+fi
+
+# Frontend deploys use /home/zulip/deployments; without this, the
+# install directory is also only readable by root.
 deploy_path=$("$ZULIP_PATH"/scripts/lib/zulip_tools.py make_deploy_path)
 mv "$ZULIP_PATH" "$deploy_path"
 ln -nsf /home/zulip/deployments/next "$ZULIP_PATH"
@@ -520,16 +539,6 @@ if has_class "zulip::app_frontend_base"; then
     # assets.
     su zulip -c '/home/zulip/deployments/current/tools/update-prod-static'
 fi
-fi
-
-# Set up a basic .gitconfig for the 'zulip' user
-if [ -n "$ZULIP_ADMINISTRATOR" ]; then
-    (
-        cd / # Make sure the current working directory is readable by zulip
-        su zulip -c "git config --global user.email $ZULIP_ADMINISTRATOR"
-        su zulip -c "git config --global user.name 'Zulip Server ($EXTERNAL_HOST)'"
-    )
-fi
 
 if [ -n "$NO_INIT_DB" ]; then
     set +x
@@ -537,15 +546,16 @@ if [ -n "$NO_INIT_DB" ]; then
 
 Success!
 
- Stopping because --no-init-db was passed.
+Stopping because --no-init-db was passed.  To complete the
- To complete the installation, configure PostgreSQL and then run:
+installation, configure PostgreSQL by creating the database and
+database user, and then run:
 
    su zulip -c '/home/zulip/deployments/current/scripts/setup/initialize-database'
    su zulip -c '/home/zulip/deployments/current/manage.py generate_realm_creation_link'
 EOF
     exit 0
-fi
+else
-
+    /home/zulip/deployments/current/scripts/setup/create-database
     su zulip -c '/home/zulip/deployments/current/scripts/setup/initialize-database --quiet'
-
     su zulip -c '/home/zulip/deployments/current/manage.py generate_realm_creation_link'
+fi