diff --git a/juju/application.py b/juju/application.py
index 9671c5b0b..c3fddbcad 100644
--- a/juju/application.py
+++ b/juju/application.py
@@ -12,6 +12,7 @@
 #     See the License for the specific language governing permissions and
 #     limitations under the License.
 
+import hashlib
 import json
 import logging
 import pathlib
@@ -433,6 +434,40 @@ async def get_actions(self, schema=False):
             actions = {k: v.description for k, v in actions.items()}
         return actions
 
+    def attach_resource(self, resource_name, file_name, file_obj):
+        """Updates the resource for an application by uploading file from
+        local disk to the Juju controller.
+
+        :param str resource_name: Name of the resource to be updated.
+        :param str file_name: Name of the local file to be uploaded.
+        :param TextIOWrapper file_obj: Actual object to be read for data.
+        """
+        conn, headers, path_prefix = self.connection.https_connection()
+
+        url = "{}/applications/{}/resources/{}".format(
+            path_prefix, self.name, resource_name)
+
+        data = file_obj.read()
+
+        headers['Content-Type'] = 'application/octet-stream'
+        headers['Content-Length'] = len(data)
+        headers['Content-Sha384'] = hashlib.sha384(bytes(data, 'utf-8')).hexdigest()
+
+        file_name = str(file_name)
+        if not file_name.startswith('./'):
+            file_name = './' + file_name
+
+        headers['Content-Disposition'] = "form-data; filename=\"{}\"".format(file_name)
+        headers['Accept-Encoding'] = 'gzip'
+        headers['Bakery-Protocol-Version'] = 3
+        headers['Connection'] = 'close'
+
+        conn.request('PUT', url, data, headers)
+        response = conn.getresponse()
+        result = response.read().decode()
+        if not response.status == 200:
+            raise JujuError(result)
+
     async def get_resources(self):
         """Return resources for this application.
 
diff --git a/tests/integration/file-resource-charm/test.file b/tests/integration/file-resource-charm/test.file
index e69de29bb..191028156 100644
--- a/tests/integration/file-resource-charm/test.file
+++ b/tests/integration/file-resource-charm/test.file
@@ -0,0 +1 @@
+foo
\ No newline at end of file
diff --git a/tests/integration/test_model.py b/tests/integration/test_model.py
index 2c1888221..69dafefff 100644
--- a/tests/integration/test_model.py
+++ b/tests/integration/test_model.py
@@ -645,6 +645,22 @@ async def test_local_file_resource_charm(event_loop):
         assert ress['file-res']
 
 
+@base.bootstrapped
+@pytest.mark.asyncio
+async def test_attach_resource(event_loop):
+    charm_path = TESTS_DIR / 'integration' / 'file-resource-charm'
+    async with base.CleanModel() as model:
+        resources = {"file-res": "test.file"}
+        app = await model.deploy(str(charm_path), resources=resources)
+        assert 'file-resource-charm' in model.applications
+
+        await model.wait_for_idle()
+        assert app.units[0].agent_status == 'idle'
+
+        with open(str(charm_path / 'test.file')) as f:
+            app.attach_resource('file-res', 'test.file', f)
+
+
 @base.bootstrapped
 @pytest.mark.asyncio
 async def test_store_resources_bundle(event_loop):