feat: Developer Certificate of Origin

Reviewed-on: #17
Fixes: #16
Signed-off-by: Awiteb <a@4rs.nl>

.forgejo/workflows/dco_checker.yml

@@ -0,0 +1,29 @@
+name: DCO checker
+
+on:
+  pull_request:
+    branches: [master]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  check:
+    name: DCO checker
+    runs-on: debian
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: DCO checker
+        run: |
+          commits=$(git rev-list origin/master..HEAD)
+          for commit in $commits; do
+              commit_subject=$(git show --quiet --format=%s $commit)
+              commit_sha=$(echo $commit | cut -c1-10)
+              echo "Checking commit $commit_sha \"$commit_subject\""
+              if ! git show --quiet --format=%B $commit | grep -q "Signed-off-by:"; then
+                  author=$(git show --quiet --format=%an $commit)
+                  echo "Commit $commit by $author is missing the 'Signed-off-by:' line"
+                  exit 1
+              fi
+          done
+          echo "All commits have the 'Signed-off-by:' line."

CONTRIBUTING.md

@@ -16,6 +16,27 @@ If you have a feature request or an idea for improving oxidetalis, we encourage
 you to open a new issue on the Forgejo repository. Please describe the feature
 or improvement in detail and provide any relevant context or examples.
 
+## Developer Certificate of Origin (DCO)
+Please note that all contributions to oxidetalis must be made under the terms of
+the Developer Certificate of Origin (DCO). This is a legal statement that
+certifies that you have the right to contribute the code and that you agree to
+license it under the project's licenses. Please read the DCO carefully before
+making a contribution, you can find the DCO here [DCO](./DCO).
+
+To indicate that you agree to the terms of the DCO, you can add a
+`Signed-off-by` line to your commit messages. This can be done by adding the
+`-s` flag to the `git commit` command, for example:
+
+```bash
+git commit -s -m "feat: Add new feature"
+```
+
+> **Note**
+>
+> We will not accept contributions that do not include the `Signed-off-by` line
+> in the commit message. We may ask you to re-submit your contribution with the
+> `Signed-off-by` line if it is missing.
+
 ## Writing Code
 Before you start writing code, please open a new issue first to discuss the
 proposed changes. This will help ensure that your contribution is aligned with

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.