packaging: remove dependency on gpg

Ubuntu 20.04 focal's python3-gpg does not correctly provide the python-package's metadata.
https://bugs.launchpad.net/ubuntu/+source/gpgme1.0/+bug/1977645
The dependency can be reactivated when the bug is fixed upstream

And document the dependencies in the README.md

README.md

@@ -11,11 +11,19 @@ Installation
 Dependencies
 ------------
 
+These libraries and programs are required:
+- The python library `psycopg2` (`python3-psycopg2`) for PostgreSQL communication.
+- The python library `gpg` (`python3-gpg`), part of the library gpgme.
+  Due to issues with Ubuntu 20.04, this dependency is not installed when installed with `pip` or `setup.py`
+  Other means of distributions (deb packages) are not affected by this bug.
+- GnuPG (v>=2.2) for `python3-gpg`.
+
 As a Python3 application, see the `install_requires` section
 in setup.py for its dependencies.
 
-If you use setuptools, it will check the hard requirements
-and install a runable script. For an installation from source:
+If you install the deb-packages, the package management handles all dependencies.
+
+For an installation from source use this command:
 ```
 pip3 install -v -e .
 ```

debian/changelog

@@ -1,4 +1,13 @@
-intelmq-mailgen (1.3.0-1) UNRELEASED; urgency=medium
+intelmq-mailgen (1.3.0-2) stable; urgency=medium
+
+  * Remove python package's dependency on 'gpg'.
+    Due to a bug in python3-gpg of Ubuntu Focal, intelmqcbmail would always
+    fail on start.
+    See https://bugs.launchpad.net/ubuntu/+source/gpgme1.0/+bug/1977645
+
+ -- Sebastian Wagner <[email protected]>  Wed, 15 Jun 2022 14:36:56 +0200
+
+intelmq-mailgen (1.3.0-1) stable; urgency=medium
 
   * Add revision.
 

setup.py

@@ -48,9 +48,13 @@
 
     install_requires=[
         'psycopg2',
-        'gpg >= 1.10',  # /!\ can (probably) **not** be installed via pip
-        # Additional requirements:
-        # * GnuPG (v>=2.2) for python3-gpg
+        # Ubuntu 20.04 focal's python3-gpg does not correctly provide the python-package's metadata.
+        # Requiring gpg here would result in
+        # > pkg_resources.DistributionNotFound: The 'gpg>=1.10' distribution was not found and is required by intelmqmail
+        # https://bugs.launchpad.net/ubuntu/+source/gpgme1.0/+bug/1977645
+        # The dependency can be reactivated when the bug is fixed upstream
+        # 'gpg >= 1.10',  # /!\ can (probably) **not** be installed via pip
+
         # * (optional) pyxarf v>0.0.5 for python3 installed
         #    https://github.com/xarf/python-xarf
         #    (v==0.0.5 does **not** work)