diff --git a/docs/images/gbp-buildpackage.uml b/docs/images/gbp-buildpackage.uml
new file mode 100644
--- /dev/null
+++ b/docs/images/gbp-buildpackage.uml
@@ -0,0 +1,46 @@
+@startuml
+  participant REPO as "git-repository"
+  participant FORGE as "phabricator forge"
+  participant CI as "gbp-buildpackage job"
+  participant DEBIAN_REPO as "debian repository"
+  activate REPO
+  activate CI
+
+  REPO->CI: new tag on branch debian/unstable-swh (or debian/stretch-swh)
+
+  alt If params.PHID is set
+    activate FORGE
+    CI->FORGE: pyarcanist sends a notification message on starting job
+  end
+
+  CI-->CI: Clone repository locally
+  CI-->CI: Checks for right setup (debian/changelog ok, debian/gbp.conf ok, etc...)
+  alt if setup checks are fine
+    CI-->CI: add ceph's gpg public key in job agent node
+    CI-->CI: builds debian package from source for "various" targets\ndepending on params (extra debian repository, dependency resolver, etc...)\nor debian/changelog (debian/unstable-swh, debian/stretch-swh)
+    alt if params.DO_UPLOAD is true
+      CI-->CI: jenkins signs the *.changes file
+      activate DEBIAN_REPO
+      CI->DEBIAN_REPO: uploads the debian package
+      deactivate DEBIAN_REPO
+    end
+    alt if params.DO_TAG
+      CI-->REPO: gbp pushes the new tag
+      deactivate REPO
+    end
+  end
+
+  activate FORGE
+  CI->FORGE: pyarcanist sends a notification message on job's status
+  deactivate FORGE
+
+  legend left
+    | short name        | description |
+    | debian repo       | https://debian.softwareheritage.org |
+    | phabricator forge | https://forge.softwareheritage.org |
+    | params.PHID       | job parameter to identify a specific phabricator git repository |
+    | params.DO_UPLOAD  | job parameter to upload or not the package to the debian repo |
+    | params.DO_TAG     | job parameter to effectively push the new tag or not |
+  endlegend
+
+@enduml