chore: DCO (#706)

Part of #508

CONTRIBUTING.md

@@ -232,6 +232,13 @@ release. Therefore please following these guidelines to the letter:
   - If this is a breaking change, the last paragraph should describe the
     breaking change with the prefix `BREAKING CHANGE: xxxxxx`.
 
+#### Developer Certificate Of Origin (DCO)
+
+Every commit should be signed-off in compliance with the [Developer Certificate Of Origin](./DCO).
+You can sign your commits by using the `git commit -s` command.
+
+> To configure automatic signoff, see [git-hooks](./git-hooks/README.md).
+
 ## Documentation
 
 Documentation is rendered from markdown using

DCO

@@ -0,0 +1,34 @@
+Developer Certificate of Origin
+Version 1.1
+
+Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+
+Developer's Certificate of Origin 1.1
+
+By making a contribution to this project, I certify that:
+
+(a) The contribution was created in whole or in part by me and I
+    have the right to submit it under the open source license
+    indicated in the file; or
+
+(b) The contribution is based upon previous work that, to the best
+    of my knowledge, is covered under an appropriate open source
+    license and I have the right under that license to submit that
+    work with modifications, whether created in whole or in part
+    by me, under the same open source license (unless I am
+    permitted to submit under a different license), as indicated
+    in the file; or
+
+(c) The contribution was provided directly to me by some other
+    person who certified (a), (b) or (c) and I have not modified
+    it.
+
+(d) I understand and agree that this project and the contribution
+    are public and that a record of the contribution (including all
+    personal information I submit with it, including my sign-off) is
+    maintained indefinitely and may be redistributed consistent with
+    this project or the open source license(s) involved.

git-hooks/README.md

@@ -0,0 +1,9 @@
+# Git Hooks
+
+This directory contains git hooks that the core team uses for various tasks.
+
+- Commit signoff for automatic compliance of the [DCO](../CONTRIBUTING.md#developer-certificate-of-origin-dco).
+
+## Setup
+
+To setup these git hooks, run `./git-hooks/setup.sh` from the root directory of the project.

git-hooks/prepare-commit-msg

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+NAME=$(git config user.name)
+EMAIL=$(git config user.email)
+
+if [ -z "$NAME" ]; then
+    echo "empty git config user.name"
+    exit 1
+fi
+
+if [ -z "$EMAIL" ]; then
+    echo "empty git config user.email"
+    exit 1
+fi
+
+git interpret-trailers --if-exists doNothing --trailer \
+    "Signed-off-by: $NAME <$EMAIL>" \
+    --in-place "$1"

git-hooks/setup.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+##############################################
+# Setup shared .git hooks for this project.
+#
+
+hooksdir="$(cd $(dirname $0) && pwd)"
+
+git config core.hooksPath ${hooksdir}
+echo "Configured core.hooksPath to ${hooksdir}"