Bug#864777: initramfs-tools: Please support a tmpfs boot mode
Package: initramfs-tools
Version: 0.130
Severity: normal
Tags: patch
Hi,
The tmpfs boot mode allows one to operate a disk-less live system by
downloading a root tarball (that can be created with debootstrap) and
extracting it to a tmpfs root partition.
The tmpfs boot mode is similar to the nfs boot mode, but it does not
rely on any external service (after booting). We use this boot mode for
our compute nodes. I have attached a patch to support this boot mode and
tested it with qemu and on real hardware.
I am willing to maintain this boot mode and fix bugs in this part.
--
Benjamin Drung
System Developer
Debian & Ubuntu Developer
ProfitBricks GmbH
Greifswalder Str. 207
D - 10405 Berlin
Email: benjamin.drung@profitbricks.com
Web: https://www.profitbricks.com
Sitz der Gesellschaft: Berlin.
Registergericht: Amtsgericht Charlottenburg, HRB 125506B.
Geschäftsführer: Achim Weiss.
>From 7cb2a6e5fb601edbad7359157f135fe17194a49d Mon Sep 17 00:00:00 2001
From: Benjamin Drung <bdrung@debian.org>
Date: Mon, 12 Jun 2017 15:31:58 +0200
Subject: [PATCH 1/2] Fix indentation (spaces to tabs)
---
init | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/init b/init
index 1334dca..4100d93 100755
--- a/init
+++ b/init
@@ -81,7 +81,7 @@ for x in $(cat /proc/cmdline); do
if [ -z "${BOOT}" ] && [ "$ROOT" = "/dev/nfs" ]; then
BOOT=nfs
fi
- ;;
+ ;;
rootflags=*)
ROOTFLAGS="-o ${x#rootflags=}"
;;
@@ -111,7 +111,7 @@ for x in $(cat /proc/cmdline); do
resume=*)
RESUME="${x#resume=}"
case $RESUME in
- UUID=*)
+ UUID=*)
RESUME="/dev/disk/by-uuid/${RESUME#UUID=}"
esac
;;
--
2.11.0
>From d8c7dd1922c9ba8bb63156843c4daf869b765c6b Mon Sep 17 00:00:00 2001
From: Benjamin Drung <benjamin.drung@profitbricks.com>
Date: Wed, 7 Jun 2017 18:04:47 +0200
Subject: [PATCH 2/2] Add tmpfs boot mode
The tmpfs boot mode allows one to operate a disk-less live system by downloading
a root tarball (that can be created with debootstrap) and extracting it to a
tmpfs root partition.
---
conf/initramfs.conf | 14 +++++
hooks/tmpfs | 36 ++++++++++++
init | 14 ++++-
initramfs-tools.8 | 21 ++++---
initramfs.conf.5 | 9 +++
scripts/tmpfs | 158 ++++++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 241 insertions(+), 11 deletions(-)
create mode 100755 hooks/tmpfs
create mode 100644 scripts/tmpfs
diff --git a/conf/initramfs.conf b/conf/initramfs.conf
index f0f5071..d75fe04 100644
--- a/conf/initramfs.conf
+++ b/conf/initramfs.conf
@@ -62,3 +62,17 @@ DEVICE=
NFSROOT=auto
+#
+# tmpfs section of the config.
+#
+
+#
+# ROOTSIZE: ...
+#
+# The size of the tmpfs root mount in bytes, and rounded up to entire pages.
+# This option accepts a suffix % to limit the instance to that percentage of
+# your physical RAM or a suffix k, m or g for Ki, Mi, Gi (binary kilo (kibi),
+# binary mega (mebi) and binary giga (gibi)).
+#
+
+ROOTSIZE=50%
diff --git a/hooks/tmpfs b/hooks/tmpfs
new file mode 100755
index 0000000..687000f
--- /dev/null
+++ b/hooks/tmpfs
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+PREREQ=""
+
+prereqs()
+{
+ echo "$PREREQ"
+}
+
+case $1 in
+# get pre-requisites
+prereqs)
+ prereqs
+ exit 0
+ ;;
+esac
+
+# Hook for supporting tmpfs boot mode
+
+. /usr/share/initramfs-tools/hook-functions
+
+# GNU tar is needed for xattrs support
+if test -e /bin/tar; then
+ test -z "$DESTDIR" || rm -f ${DESTDIR}/bin/tar
+ copy_exec /bin/tar
+fi
+
+# pixz is used to speed up the decompression
+if test -e /usr/bin/pixz; then
+ copy_exec /usr/bin/pixz
+fi
+
+# libnss_dns is needed for resolving hosts by name
+if test -e /lib/x86_64-linux-gnu/libnss_dns.so.2; then
+ copy_exec /lib/x86_64-linux-gnu/libnss_dns.so.2
+fi
diff --git a/init b/init
index 4100d93..735afad 100755
--- a/init
+++ b/init
@@ -78,8 +78,15 @@ for x in $(cat /proc/cmdline); do
;;
root=*)
ROOT=${x#root=}
- if [ -z "${BOOT}" ] && [ "$ROOT" = "/dev/nfs" ]; then
- BOOT=nfs
+ if [ -z "${BOOT}" ]; then
+ case ${ROOT} in
+ /dev/nfs)
+ BOOT=nfs
+ ;;
+ http*)
+ BOOT=tmpfs
+ ;;
+ esac
fi
;;
rootflags=*)
@@ -96,6 +103,9 @@ for x in $(cat /proc/cmdline); do
;;
esac
;;
+ rootsize=*)
+ ROOTSIZE="${x#rootsize=}"
+ ;;
nfsroot=*)
NFSROOT="${x#nfsroot=}"
;;
diff --git a/initramfs-tools.8 b/initramfs-tools.8
index 0eee050..aff69fc 100644
--- a/initramfs-tools.8
+++ b/initramfs-tools.8
@@ -27,6 +27,8 @@ the binary to hand over execution to on the root fs after the initramfs scripts
\fB\fI root= "<path to blockdevice>"
the device node to mount as the root file system.
The recommended usage is to specify the UUID as followed "root=UUID=xxx".
+When using the tmpfs boot mode, specify a URL to a (compressed) root tarball
+here.
.TP
\fB\fI rootfstype
@@ -62,7 +64,7 @@ bootarg.
.TP
\fB\fI boot
-either local or NFS (affects which initramfs scripts are run, see the "Subdirectories" section under boot scripts).
+local, NFS, or tmpfs (affects which initramfs scripts are run, see the "Subdirectories" section under boot scripts).
.TP
\fB\fI resume
@@ -432,9 +434,9 @@ have been loaded.
.TP
\fB\fI
-local-top OR nfs-top
+local-top, nfs-top, OR tmpfs-top
After these scripts have been executed, the root device node is expected to be
-present (local) or the network interface is expected to be usable (NFS).
+present (local) or the network interface is expected to be usable (NFS, tmpfs).
.TP
\fB\fI
@@ -447,16 +449,17 @@ try again.
.TP
\fB\fI
-local-premount OR nfs-premount
+local-premount, nfs-premount, OR tmpfs-premount
are run after the sanity of the root device has been verified (local) or the
-network interface has been brought up (NFS), but before the actual root fs has
-been mounted.
+network interface has been brought up (NFS, tmpfs) and the empty root partition
+is mounted (tmpfs), but before the actual root fs has been mounted.
.TP
\fB\fI
-local-bottom OR nfs-bottom
-are run after the rootfs has been mounted (local) or the NFS root share has
-been mounted.
+local-bottom, nfs-bottom, OR tmpfs-bottom
+are run after the rootfs has been mounted (local), the NFS root share has
+been mounted, or the root tarball was extract to the mounted tmpfs root
+partition.
.TP
\fB\fI
diff --git a/initramfs.conf.5 b/initramfs.conf.5
index b4eea70..e5d0073 100644
--- a/initramfs.conf.5
+++ b/initramfs.conf.5
@@ -99,6 +99,15 @@ A root bootarg overrides that special setting.
Defaults to \fIauto\fP in order to pick up value from DHCP server.
Otherwise you need to specify \fIHOST:MOUNT\fP.
+.SH VARIABLES FOR TMPFS BOOT
+
+.TP
+\fB ROOTSIZE
+The size of the tmpfs root mount in bytes, and rounded up to entire pages. This
+option accepts a suffix % to limit the instance to that percentage of your
+physical RAM or a suffix k, m or g for Ki, Mi, Gi (binary kilo (kibi), binary
+mega (mebi) and binary giga (gibi)). The default is half of the memory (50%).
+
.SH FILES
.TP
.I /etc/initramfs-tools/initramfs.conf
diff --git a/scripts/tmpfs b/scripts/tmpfs
new file mode 100644
index 0000000..e21cbac
--- /dev/null
+++ b/scripts/tmpfs
@@ -0,0 +1,158 @@
+# Diskless system running on tmpfs -*- shell-script -*-
+
+persist_networking()
+{
+ if [ -n "$DNSDOMAIN" ]; then
+ [ "${quiet}" = "y" ] || echo "/etc/resolv.conf: Setting local domain name to $DNSDOMAIN"
+ echo "domain $DNSDOMAIN" >> /etc/resolv.conf
+ fi
+ if [ -n "$IPV4DNS0" -a "$IPV4DNS0" != "0.0.0.0" ]; then
+ [ "${quiet}" = "y" ] || echo "/etc/resolv.conf: Adding DNS ${IPV4DNS0}"
+ echo "nameserver ${IPV4DNS0}" >> /etc/resolv.conf
+ fi
+ if [ -n "$IPV4DNS1" -a "$IPV4DNS1" != "0.0.0.0" ]; then
+ [ "${quiet}" = "y" ] || echo "/etc/resolv.conf: Adding DNS ${IPV4DNS1}"
+ echo "nameserver ${IPV4DNS1}" >> /etc/resolv.conf
+ fi
+ if [ -n "$DOMAINSEARCH" ]; then
+ [ "${quiet}" = "y" ] || echo "/etc/resolv.conf: Setting search list to $DNSDOMAIN $DOMAINSEARCH"
+ echo "search $DNSDOMAIN $DOMAINSEARCH" >> /etc/resolv.conf
+ fi
+ if [ -n "$HOSTNAME" ]; then
+ [ "${quiet}" = "y" ] || echo "Setting hostname to $hostname"
+ echo $HOSTNAME > /etc/hostname
+ if [ -n "$DNSDOMAIN" ]; then
+ names="$HOSTNAME.$DNSDOMAIN $HOSTNAME"
+ else
+ names="$HOSTNAME"
+ fi
+ echo "127.0.0.1 localhost
+127.0.1.1 $names
+
+# The following lines are desirable for IPv6 capable hosts
+::1 localhost ip6-localhost ip6-loopback
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters" > /etc/hosts
+ fi
+}
+
+tmpfs_top()
+{
+ if [ "${tmpfs_top_used}" != "yes" ]; then
+ [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/tmpfs-top"
+ run_scripts /scripts/tmpfs-top
+ [ "$quiet" != "y" ] && log_end_msg
+ fi
+ tmpfs_top_used=yes
+
+ # For DHCP
+ modprobe af_packet
+
+ wait_for_udev 10
+
+ [ "$quiet" = "y" ] || log_begin_msg "Starting networking"
+ configure_networking || panic "Network configuration failed."
+ [ "$quiet" = "y" ] || log_end_msg
+
+ persist_networking
+
+ mount -t tmpfs -o size=${ROOTSIZE-50%} tmpfs ${rootmnt} || panic "tmpfs root mount failed."
+}
+
+tmpfs_premount()
+{
+ if [ "${tmpfs_premount_used}" != "yes" ]; then
+ [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/tmpfs-premount"
+ run_scripts /scripts/tmpfs-premount
+ [ "$quiet" != "y" ] && log_end_msg
+ fi
+ tmpfs_premount_used=yes
+}
+
+tmpfs_bottom()
+{
+ if [ "${tmpfs_premount_used}" = "yes" ] || [ "${tmpfs_top_used}" = "yes" ]; then
+ [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/tmpfs-bottom"
+ run_scripts /scripts/tmpfs-bottom
+ [ "$quiet" != "y" ] && log_end_msg
+ fi
+ tmpfs_premount_used=no
+ tmpfs_top_used=no
+}
+
+sleep_break()
+{
+ local timeout=$1
+ if test "$timeout" -ge 1; then
+ echo "Press x (in the next $timeout seconds) to open a shell"
+ read -t $timeout -r -s -n 1 input
+ [ "$input" = "x" ] && panic "Spawning shell within the initramfs as requested"
+ fi
+}
+
+extract()
+{
+ local archive="$1"
+ local TAROPTS=""
+ echo "Extracting ${archive} to ${rootmnt}..."
+ case "$archive" in
+ *.xz)
+ if test -e /usr/bin/pixz; then
+ TAROPTS=-Ipixz
+ fi
+ ;;
+ esac
+ /bin/tar $TAROPTS --xattrs --xattrs-include='*' -xf "$archive" -C "${rootmnt}" || panic "Extracting "${archive}" failed."
+}
+
+tmpfs_mount_root()
+{
+ host=$(hostname)
+ while ! fqdn=$(hostname -f); do
+ local sleep_t="$((RANDOM%30+10))"
+ echo "Failed to determine fully qualified domain name (FQDN), retry in $sleep_t seconds..."
+ sleep_break $sleep_t
+ done
+
+ IFS=','
+ for url in $ROOT; do
+ # Replace %hostname and %fqdn in the URL
+ url=$(echo "$url" | sed "s/%hostname/$host/g;s/%fqdn/$fqdn/g")
+ filename=/tmp/$(basename "$url")
+
+ echo "Downloading ${url}..."
+ while ! wget -O "${filename}" "${url}"; do
+ local sleep_t="$((RANDOM%30+10))"
+ echo "Download failed, retry in $sleep_t seconds..."
+ sleep_break $sleep_t
+ done
+ echo "Download successful"
+
+ extract "${filename}"
+ rm "${filename}"
+ done
+ unset IFS
+}
+
+mountroot()
+{
+ tmpfs_mount_root
+}
+
+mount_top()
+{
+ # Note, also called directly in case it's overridden.
+ tmpfs_top
+}
+
+mount_premount()
+{
+ # Note, also called directly in case it's overridden.
+ tmpfs_premount
+}
+
+mount_bottom()
+{
+ # Note, also called directly in case it's overridden.
+ tmpfs_bottom
+}
--
2.11.0
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