diff mbox series

[03/12] docker-engine: add support for init processes

Message ID 20171019002257.27646-3-christian@paral.in
State Superseded
Headers show
Series [01/12] dumb-init: new package | expand

Commit Message

Christian Stewart Oct. 19, 2017, 12:22 a.m. UTC 
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(+)

Comments

Yann E. MORIN Oct. 21, 2017, 1:51 p.m. UTC | #1 
Christian, All,

On 2017-10-18 20:22 -0400, Christian Stewart spake thusly:
> 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 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), \

Why not:

    $(if $(BR2_PACKAGE_DOCKER_ENGINE_DAEMON),\
        ln -fs $(DOCKER_ENGINE_INIT) $(TARGET_DIR)/usr/bin/docker-init
    )

Regards,
Yann E. MORIN.

> +		ln -fs $(DOCKER_ENGINE_INIT) $(TARGET_DIR)/usr/bin/docker-init
> +	)
>  endef
>  
>  $(eval $(generic-package))
> -- 
> 2.13.6
> 
> _______________________________________________
> buildroot mailing list
> buildroot@busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot
Thomas Petazzoni Oct. 21, 2017, 1:51 p.m. UTC | #2 
Hello,

On Wed, 18 Oct 2017 20:22:48 -0400, 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.

Did you meant "dump-init" here instead of "docker-init" ?

Thomas
Christian Stewart Oct. 24, 2017, 3:28 a.m. UTC | #3 
Hi Yann, Thomas,

On Sat, Oct 21, 2017, 9:51 AM Yann E. MORIN <yann.morin.1998@free.fr> wrote:
> Why not:
>
>     $(if $(BR2_PACKAGE_DOCKER_ENGINE_DAEMON),\
>         ln -fs $(DOCKER_ENGINE_INIT) $(TARGET_DIR)/usr/bin/docker-init
>     )

That would work too.

Best,
Christian
Christian Stewart Oct. 24, 2017, 3:29 a.m. UTC | #4 
Hi Thomas,

On Sat, Oct 21, 2017 at 9:51 AM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Did you meant "dump-init" here instead of "docker-init" ?

No, definitely not.

Best,
Christian
Arnout Vandecappelle Oct. 24, 2017, 9:31 p.m. UTC | #5 
On 24-10-17 05:29, Christian Stewart wrote:
> Hi Thomas,
> 
> On Sat, Oct 21, 2017 at 9:51 AM, Thomas Petazzoni
> <thomas.petazzoni@free-electrons.com> wrote:
>> Did you meant "dump-init" here instead of "docker-init" ?
> 
> No, definitely not.

 I think you did. You had written

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

so that would mean that the docker-init binary can be backed by docker-init...

 Regards,
 Arnout
Christian Stewart Oct. 24, 2017, 11:55 p.m. UTC | #6 
Hi Arnout,

On Tue, Oct 24, 2017, 5:31 PM Arnout Vandecappelle <arnout@mind.be> wrote:

> On 24-10-17 05:29, Christian Stewart wrote:
> > On Sat, Oct 21, 2017 at 9:51 AM, Thomas Petazzoni
> > <thomas.petazzoni@free-electrons.com> wrote:
> >> Did you meant "dump-init" here instead of "docker-init" ?
> >
> > No, definitely not.
>
>  I think you did. You had written
>

Definitely not "dump" init. Yes, I did mean dumb-init and just misspelled
it the first time.

Best,
Christian
Hi Arnout,<br><br><div class="gmail_quote"><div dir="ltr">On Tue, Oct 24, 2017, 5:31 PM Arnout Vandecappelle &lt;<a href="mailto:arnout@mind.be">arnout@mind.be</a>&gt; wrote:</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On 24-10-17 05:29, Christian Stewart wrote:<br>
&gt; On Sat, Oct 21, 2017 at 9:51 AM, Thomas Petazzoni<br>
&gt; &lt;<a href="mailto:thomas.petazzoni@free-electrons.com" target="_blank">thomas.petazzoni@free-electrons.com</a>&gt; wrote:<br>
&gt;&gt; Did you meant &quot;dump-init&quot; here instead of &quot;docker-init&quot; ?<br>
&gt;<br>
&gt; No, definitely not.<br>
<br>
 I think you did. You had written<br></blockquote></div><div><br></div><div>Definitely not &quot;dump&quot; init. Yes, I did mean dumb-init and just misspelled it the first time. </div><div><br></div><div>Best,</div><div>Christian</div>
diff mbox series

Patch

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))