| Message ID | 20170920030210.19446-4-christian@paral.in |
|---|---|
| State | RFC |
| Headers | show |
| Series | Upgrading Go to 1.9 and Docker to v2017.07 | expand |
On 20-09-17 05:02, Christian Stewart wrote: > 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. OK, now I get the reason to build dumb-init statically: it actually comes from outside the container, not inside. Honestly I don't understand why it takes an executable from outside the container to run inside it, but OK. > > Furthermore, this patch fixes the following Docker error: > > dockerd: level=warning msg="failed to retrieve docker-init version" On my Debian system there is no docker-init but I don't get this warning when starting docker... > > Signed-off-by: Christian Stewart <christian@paral.in> Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Small nit below. > --- > 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 05670a716e..7d9a87f7bb 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 Upstream URL is not needed here, only in the package itself. It might be useful to add some help text that indicates the difference between tini and dumb-init. Regards, Arnout > + > +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 8928f072e7..a2776ed78c 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)) >
Hi Arnout, I marked this series as RFC on patchwork, just because there are a couple of fixes I have applied and will respin after people are done reviewing. On Thu, Sep 21, 2017 at 10:37 PM, Arnout Vandecappelle <arnout@mind.be> wrote: > On my Debian system there is no docker-init but I don't get this warning when > starting docker... This is likely because Docker has changed since I wrote this patch originally, which was against a version 4 versions ago around 6 months ago. > Upstream URL is not needed here, only in the package itself. Interesting, I put it there because for some reason I remember seeing the upstream URL in the Config.in for other packages. Will remove. > It might be useful to add some help text that indicates the difference between > tini and dumb-init. Functionally there is none, but the actual implementations are just slightly different by different authors. Tini is a bit newer but backed by a less trusted source while dumb-init is old and backed by Yelp. For some reason Tini is used by the docker official distribution. Best, Christian
diff --git a/package/docker-engine/Config.in b/package/docker-engine/Config.in index 05670a716e..7d9a87f7bb 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 8928f072e7..a2776ed78c 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))
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(+)