Force error when using old versions.

Author: Juan Tirado

.github/workflows/test.yaml

@@ -3,7 +3,29 @@ name: Testing
 on: [push, pull_request]
 
 jobs:
+  lint:
+    name: Linter
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python:
+          - "3.8"
+          - "3.9"
+          - "3.10"
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v3
+    - name: Setup Python
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python }}
+    - name: Install dependencies
+      run: pip install tox
+    - name: Run linter
+      run: tox -e lint
+
   unit-tests:
+    needs: lint
     name: Unit tests
     runs-on: ubuntu-latest
     strategy:
@@ -24,9 +46,9 @@ jobs:
     - name: Run unit tests
       run: tox -e py3
 
-
   integration:
     name: Integration
+    needs: [lint, unit-tests]
     timeout-minutes: 120
     runs-on: ubuntu-latest
     strategy:

VERSION

@@ -1 +1 @@
-3.1.0-beta1
+3.1.0-b1

juju/client/connector.py

@@ -11,6 +11,11 @@
 
 log = logging.getLogger('connector')
 
+# The SUPPORTED_JUJU_API_PREFIX indicates the prefix of the
+# juju version this python-libjuju version supports. For 
+# example, "3.0." indicates that all the 3.0.x versions
+# are intended to be supported.
+SUPPORTED_JUJU_API_PREFIX = "3.0."
 
 class NoConnectionException(Exception):
     '''Raised by Connector when the connection method is called
@@ -73,6 +78,10 @@ async def connect(self, **kwargs):
                 await self._connection.close()
             self._connection = await Connection.connect(**kwargs)
 
+        # Check if we support the target controller
+        if not self._connection.info['server-version'].startswith(SUPPORTED_JUJU_API_PREFIX):
+            raise JujuConnectionError("juju server-version %s not supported" % self._connection.info["server-version"])
+
     async def disconnect(self):
         """Shut down the watcher task and close websockets.
         """