From 32df032c5944326e351a7910a877d1992563f791 Mon Sep 17 00:00:00 2001
From: Jason Tedor <jason@tedor.me>
Date: Thu, 1 Dec 2016 17:23:51 -0500
Subject: [PATCH] Add option to skip kernel parameters on install

During package install on systemd-based systems, we try to set
vm.max_map_count. On some systems (e.g., containers), users do not have
the ability to tune these parameters from within the container. This
commit provides an option for these users to skip setting such kernel
parameters.

Relates #21899
---
 distribution/src/main/packaging/scripts/postinst  | 15 +++++++++++----
 docs/reference/setup/install/deb.asciidoc         |  1 +
 docs/reference/setup/install/rpm.asciidoc         |  2 ++
 .../install/skip-set-kernel-parameters.asciidoc   |  2 ++
 4 files changed, 16 insertions(+), 4 deletions(-)
 create mode 100644 docs/reference/setup/install/skip-set-kernel-parameters.asciidoc

diff --git a/distribution/src/main/packaging/scripts/postinst b/distribution/src/main/packaging/scripts/postinst
index 3d5eeeedd8f..d9f7e6ae126 100644
--- a/distribution/src/main/packaging/scripts/postinst
+++ b/distribution/src/main/packaging/scripts/postinst
@@ -52,10 +52,17 @@ case "$1" in
 esac
 
 # to pick up /usr/lib/sysctl.d/elasticsearch.conf
-if command -v /usr/lib/systemd/systemd-sysctl > /dev/null; then
-    /usr/lib/systemd/systemd-sysctl
-elif command -v /lib/systemd/systemd-sysctl > /dev/null; then
-    /lib/systemd/systemd-sysctl
+if [ "${ES_SKIP_SET_KERNEL_PARAMETERS:-false}" == "false" ]; then
+    if command -v /usr/lib/systemd/systemd-sysctl > /dev/null; then
+        /usr/lib/systemd/systemd-sysctl
+    elif command -v /lib/systemd/systemd-sysctl > /dev/null; then
+        /lib/systemd/systemd-sysctl
+    fi
+elif [ "$ES_SKIP_SET_KERNEL_PARAMETERS" == "true" ]; then
+    echo "skipping setting kernel parameters"
+else
+    echo "unrecognized value [$ES_SKIP_SET_KERNEL_PARAMETERS] for ES_SKIP_SET_KERNEL_PARAMETERS; must [false] (default) or [true]"
+    exit 1
 fi
 
 if [ "x$IS_UPGRADE" != "xtrue" ]; then
diff --git a/docs/reference/setup/install/deb.asciidoc b/docs/reference/setup/install/deb.asciidoc
index c1d0425b430..6ca635ce06e 100644
--- a/docs/reference/setup/install/deb.asciidoc
+++ b/docs/reference/setup/install/deb.asciidoc
@@ -96,6 +96,7 @@ Examine +/etc/apt/sources.list.d/elasticsearch-{major-version}.list+ for the dup
 
 endif::[]
 
+include::skip-set-kernel-parameters.asciidoc[]
 
 [[install-deb]]
 ==== Download and install the Debian package manually
diff --git a/docs/reference/setup/install/rpm.asciidoc b/docs/reference/setup/install/rpm.asciidoc
index acf9d6f2418..b737fbff127 100644
--- a/docs/reference/setup/install/rpm.asciidoc
+++ b/docs/reference/setup/install/rpm.asciidoc
@@ -112,6 +112,8 @@ sudo rpm --install elasticsearch-{version}.rpm
 
 endif::[]
 
+include::skip-set-kernel-parameters.asciidoc[]
+
 include::init-systemd.asciidoc[]
 
 [[rpm-running-init]]
diff --git a/docs/reference/setup/install/skip-set-kernel-parameters.asciidoc b/docs/reference/setup/install/skip-set-kernel-parameters.asciidoc
new file mode 100644
index 00000000000..56406fce987
--- /dev/null
+++ b/docs/reference/setup/install/skip-set-kernel-parameters.asciidoc
@@ -0,0 +1,2 @@
+NOTE: On systemd-based distributions, the installation scripts will attempt to set kernel parameters (e.g.,
+`vm.max_map_count`); you can skip this by setting the environment variable `ES_SKIP_SET_KERNEL_PARAMETERS` to `true`.