diff --git a/docs/images/gbp-buildpackage.uml b/docs/images/gbp-buildpackage.uml
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+@startuml
+  participant JOB as "job"
+  participant REPO as "git-repository (~phabricator forge)"
+  participant CI as "gbp-buildpackage job"
+  participant DEBIAN_SWH_REPO as "swh debian repository"
+  participant DEBIAN_REPO as "debian repositories"
+  activate REPO
+  activate CI
+  activate DEBIAN_SWH_REPO
+  activate DEBIAN_REPO
+
+  activate JOB
+  JOB->REPO: pushes new tag on branch \ndebian/unstable-swh (or debian/stretch-swh)
+  deactivate JOB
+  REPO-->CI: trigger event to notify changes
+
+  alt If params.PHID is set
+    CI->REPO: pyarcanist sends a notification message on starting job
+  end
+
+  CI-->REPO: 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)
+    CI-->DEBIAN_SWH_REPO: (build) fetches potential dependencies 
+    CI->DEBIAN_REPO: (build) fetches dependencies
+    alt if params.DO_UPLOAD is true
+      CI-->CI: signs the *.changes file
+      CI->DEBIAN_SWH_REPO: uploads the debian package
+    end
+    alt if params.DO_TAG
+      CI->REPO: pushes the new tag
+    end
+  end
+
+  activate REPO
+  CI->REPO: pyarcanist sends a notification message on job's status
+  deactivate REPO
+
+  legend left
+    | short name        | description |
+    | job               | jenkins job modifying the git repository by tagging (update-for-release, automatic-backport) |
+    | swh debian repo   | https://debian.softwareheritage.org |
+    | debian repos      | official (deb.debian.org), and more (e.g. ceph's) |
+    | 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