From d1e5ba6121af74d9d2181c8f8f9d02fd534d13f8 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@docker.com>
Date: Wed, 8 Jun 2016 11:03:11 +0100
Subject: [PATCH] Point chronyd at gateway when ntp=gateway is given on the
 kernel cmdline.

Reconfigure chronyd in a udhcpc post-bound hook and restart it, but use
conditionalrestart so it is not started if it isn't running, which is the case
during boot when this hook happens from init.d/networking via ifup, running
"service ... start" in that context results in the daemon running but the
service db saying it isn't.

Doing it in the udhcpc hook leaves a nice hole where support for getting the
NTP server via DHCP can fit in once it is available.

This also switches from using "initstepslew" to "makestep", the former was
responsible for the long delay starting chronyd (meaning we can now drop
"before chronyd" from Docker's init dependencies), while the later will force a
step if the time is out by more than the configured amount (half a second
here), meaning it will be corrected on resume. The rest of the time it chrony
will do the usual slewing to keep the clock accurate. Passing -1 as the limit
to "makestep" ensures the step will always occur, if it were positive it would
only be done that number of times.

We add "iburst" and "minpoll 2" to the default configuration file to speed up
initial sync and resync after sleep respectively, resync after sleep happens in
a couple of seconds. In "ntp=gateway" mode we also patch in "trust", this isn't
in the default config file since we won't be so sure about DHCP provided
servers, but when talking to a host provided NTP we want to use its time (for
sync accross host mounts) even if it has a crazy idea about what the time is.

With this we can also remove the 15min ntp sync, which in turn gets rid of the
need for cron.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>
---
 alpine/Dockerfile                                |  2 --
 alpine/packages/chronyd/etc/chrony/chrony.conf   |  6 ++++++
 .../chronyd/etc/udhcpc/post-bound/chronyd        | 16 ++++++++++++++++
 alpine/packages/docker/etc/init.d/docker         |  1 -
 alpine/packages/ntp15m/etc/periodic/15min/ntp    |  3 ---
 5 files changed, 22 insertions(+), 6 deletions(-)
 create mode 100644 alpine/packages/chronyd/etc/chrony/chrony.conf
 create mode 100755 alpine/packages/chronyd/etc/udhcpc/post-bound/chronyd
 delete mode 100755 alpine/packages/ntp15m/etc/periodic/15min/ntp

diff --git a/alpine/Dockerfile b/alpine/Dockerfile
index 838380b96..c1e20bbb8 100644
--- a/alpine/Dockerfile
+++ b/alpine/Dockerfile
@@ -50,7 +50,6 @@ COPY packages/diagnostics/diagnostics /usr/bin/
 COPY packages/diagnostics/diagnostics-server /usr/bin/
 COPY packages/diagnostics/etc /etc/
 COPY packages/automount/etc /etc/
-COPY packages/ntp15m/etc /etc/
 COPY packages/binfmt_misc/etc /etc/
 COPY packages/dnsfix/etc /etc/
 COPY packages/hostsettings/etc /etc/
@@ -84,7 +83,6 @@ RUN \
   rc-update add networking boot && \
   rc-update add acpid default && \
   rc-update add chronyd default && \
-  rc-update add crond default && \
   rc-update add savecache shutdown && \
   rc-update add killprocs shutdown && \
   rc-update add mount-ro shutdown && \
diff --git a/alpine/packages/chronyd/etc/chrony/chrony.conf b/alpine/packages/chronyd/etc/chrony/chrony.conf
new file mode 100644
index 000000000..4e7da8a3d
--- /dev/null
+++ b/alpine/packages/chronyd/etc/chrony/chrony.conf
@@ -0,0 +1,6 @@
+# default config
+
+server pool.ntp.org iburst minpoll 2
+makestep 0.5 -1
+keyfile /etc/chrony/chrony.keys
+driftfile /var/lib/chrony/chrony.drift
diff --git a/alpine/packages/chronyd/etc/udhcpc/post-bound/chronyd b/alpine/packages/chronyd/etc/udhcpc/post-bound/chronyd
new file mode 100755
index 000000000..3c8f0fe85
--- /dev/null
+++ b/alpine/packages/chronyd/etc/udhcpc/post-bound/chronyd
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+if [ "x$interface" != "xeth0" ] ; then exit 0 ; fi
+
+if cat /proc/cmdline | grep -q '\bntp=gateway\b' ; then
+    server=$(ip -4 route list type unicast dev eth0 exact 0/0 | awk '/^default/ { print $3 }')
+    server="$server trust"
+else
+    # TODO: consult $router
+    exit 0
+fi
+
+sed -i -e "s/^server [^ ]\+/server $server/g" /etc/chrony/chrony.conf
+
+logger -t udhcpc "Restarting chronyd with server $server"
+service -q chronyd conditionalrestart
diff --git a/alpine/packages/docker/etc/init.d/docker b/alpine/packages/docker/etc/init.d/docker
index 5bfa2d01b..cc7c2223b 100755
--- a/alpine/packages/docker/etc/init.d/docker
+++ b/alpine/packages/docker/etc/init.d/docker
@@ -3,7 +3,6 @@
 depend()
 {
 	after transfused
-	before chronyd
 }
 
 start()
diff --git a/alpine/packages/ntp15m/etc/periodic/15min/ntp b/alpine/packages/ntp15m/etc/periodic/15min/ntp
deleted file mode 100755
index 0c2d9317d..000000000
--- a/alpine/packages/ntp15m/etc/periodic/15min/ntp
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/bin/sh
-
-ntpd -n -q -p pool.ntp.org