From 5d013c218ca72c05a4b59897f702930b77838083 Mon Sep 17 00:00:00 2001
From: Alex Vandiver <alexmv@zulip.com>
Date: Fri, 20 Dec 2024 16:11:14 +0000
Subject: [PATCH] requirements: Require some swap space if installed on < 5GB
 RAM.

(cherry picked from commit 3eb501fa18a43feed7997f6c76d9767f79a0d434)
---
 docs/production/requirements.md | 13 ++++++-------
 scripts/lib/install             | 13 +++++++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/docs/production/requirements.md b/docs/production/requirements.md
index 958e077509..3d9af6a9a7 100644
--- a/docs/production/requirements.md
+++ b/docs/production/requirements.md
@@ -11,9 +11,9 @@ To run a Zulip server, you will need:
   - x86-64
   - aarch64
 - At least 2 GB RAM, and 10 GB disk space
+  - If you have < 5 GB RAM, we require some swap space; we recommend configuring
+    2 GB of swap
   - If you expect 100+ users: 4 GB RAM, and 2 CPUs
-  - If you intend to [upgrade from Git][upgrade-from-git]: 3 GB RAM, or
-    2G and at least 1G of swap configured.
 - A hostname in DNS
 - Credentials for sending email
 
@@ -63,11 +63,10 @@ sudo apt update
 
 - CPU and memory: For installations with 100+ users you'll need a
   minimum of **2 CPUs** and **4 GB RAM**. For installations with fewer
-  users, 1 CPU and 2 GB RAM is sufficient. We strongly recommend against
-  installing with less than 2 GB of RAM, as you will likely experience
-  out of memory issues installing dependencies. We recommend against
-  using highly CPU-limited servers like the AWS `t2` style instances
-  for organizations with hundreds of users (active or no).
+  users, 1 CPU and 2 GB RAM with 2 GB of swap is sufficient. We
+  recommend against using highly CPU-limited servers like the AWS `t2`
+  style instances for organizations with hundreds of users (active or
+  no).
 
 - Disk space: You'll need at least 10 GB of free disk space for a
   server with dozens of users. We recommend using an SSD and avoiding
diff --git a/scripts/lib/install b/scripts/lib/install
index 7066077c3e..decc0d59e5 100755
--- a/scripts/lib/install
+++ b/scripts/lib/install
@@ -327,6 +327,19 @@ if [ "$mem_kb" -lt 1860000 ]; then
     exit 1
 fi
 
+# Anything under 5GB, we recommended allocating 2GB of swap.  Error
+# out if there's no swap.
+swap_kb=$(grep SwapTotal /proc/meminfo | awk '{print $2}')
+if [ "$mem_kb" -lt 5000000 ] && [ "$swap_kb" -eq 0 ]; then
+    set +x
+    echo -e '\033[0;31m' >&2
+    echo "No swap allocated; when running with < 5GB of RAM, we recommend at least 2GB of swap." >&2
+    echo "https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-22-04" >&2
+    echo >&2
+    echo -e '\033[0m' >&2
+    exit 1
+fi
+
 # Do package update, e.g. do `apt-get update` on Debian
 if [ "$package_system" = apt ]; then
     # setup-apt-repo does an `apt-get update`