From 16fc5c50a96aad21f8f6b8db202269cc8fee1c36 Mon Sep 17 00:00:00 2001
From: Christian Stewart <christian@paral.in>
Date: Tue, 9 May 2017 18:03:55 -0400
Subject: [PATCH] docker-engine: add support for init processes

When a docker container is run with the --init flag, the Docker engine
uses the docker-init binary as PID 1 inside the container. This is
necessary in may cases to avoid issues with signal handling, zombie
processes, and other quirks when running as PID 1.

The docker-init binary is backed by tini on default, but optionally can
be changed to docker-init by user preference.

Furthermore, this patch fixes the following Docker error:

  dockerd: level=warning msg="failed to retrieve docker-init version"

Signed-off-by: Christian Stewart <christian@paral.in>
---
 package/docker-engine/Config.in        | 26 ++++++++++++++++++++++++++
 package/docker-engine/docker-engine.mk | 11 +++++++++++
 2 files changed, 37 insertions(+)

diff --git a/package/docker-engine/Config.in b/package/docker-engine/Config.in
index 05670a7..7d9a87f 100644
--- a/package/docker-engine/Config.in
+++ b/package/docker-engine/Config.in
@@ -33,6 +33,32 @@ config BR2_PACKAGE_DOCKER_ENGINE_STATIC_CLIENT
 
 if BR2_PACKAGE_DOCKER_ENGINE_DAEMON
 
+choice
+	bool "docker-init to use"
+	default BR2_PACKAGE_DOCKER_ENGINE_INIT_TINI
+	help
+	  The docker engine uses a minimal init process as PID 1
+	  inside containers. There are several implementations
+	  of this init process.
+
+config BR2_PACKAGE_DOCKER_ENGINE_INIT_TINI
+	bool "tini"
+	select BR2_PACKAGE_TINI
+	help
+	  Use Tini as the container init process.
+
+	  https://github.com/krallin/tini
+
+config BR2_PACKAGE_DOCKER_ENGINE_INIT_DUMB_INIT
+	bool "dumb-init"
+	select BR2_PACKAGE_DUMB_INIT
+	help
+	  Use dumb-init as the container init process.
+
+	  https://github.com/Yelp/dumb-init
+
+endchoice
+
 config BR2_PACKAGE_DOCKER_ENGINE_DRIVER_BTRFS
 	bool "btrfs filesystem driver"
 	depends on BR2_USE_MMU # btrfs-progs
diff --git a/package/docker-engine/docker-engine.mk b/package/docker-engine/docker-engine.mk
index 8928f07..a2776ed 100644
--- a/package/docker-engine/docker-engine.mk
+++ b/package/docker-engine/docker-engine.mk
@@ -50,6 +50,13 @@ endif
 ifeq ($(BR2_PACKAGE_DOCKER_ENGINE_DAEMON),y)
 DOCKER_ENGINE_BUILD_TAGS += daemon
 DOCKER_ENGINE_BUILD_TARGETS += dockerd
+
+ifeq ($(BR2_PACKAGE_DOCKER_ENGINE_INIT_DUMB_INIT),y)
+DOCKER_ENGINE_INIT = dumb-init
+else
+DOCKER_ENGINE_INIT = tini
+endif
+
 endif
 
 ifeq ($(BR2_PACKAGE_DOCKER_ENGINE_EXPERIMENTAL),y)
@@ -119,6 +126,10 @@ define DOCKER_ENGINE_INSTALL_TARGET_CMDS
 	$(foreach target,$(DOCKER_ENGINE_BUILD_TARGETS), \
 		$(INSTALL) -D -m 0755 $(@D)/bin/$(target) $(TARGET_DIR)/usr/bin/$(target)
 	)
+
+	$(if $(filter $(BR2_PACKAGE_DOCKER_ENGINE_DAEMON),y), \
+		ln -fs $(DOCKER_ENGINE_INIT) $(TARGET_DIR)/usr/bin/docker-init
+	)
 endef
 
 $(eval $(generic-package))
-- 
2.9.0.windows.1