ENH: Make jsonschema optional

README_SETUP.md

@@ -11,6 +11,10 @@ typically be installed automatically):
 - `PyYaml`
 - `PySocks`
 
+Optional packages:
+- `keyring`
+- `jsonschema`
+
 ### How to install ###
 
 #### Linux ####
@@ -66,6 +70,13 @@ cd caosdb-pylib
 pip3 install --user .
 ```
 
+For installation of optional packages, install with an additional option, e.g. for 
+validating with the caosdb json schema:
+
+```sh
+pip3 install --user .[jsonschema]
+```
+
 ## Configuration ##
 
 The  configuration is done using `ini` configuration files.

setup.py

@@ -158,10 +158,11 @@ def setup_package():
         python_requires='>=3.6',
         package_dir={'': 'src'},
         install_requires=['lxml>=3.6.4',
-                          'PyYaml>=3.12', 'future', 'PySocks>=1.6.7', 'jsonschema'],
-        extras_require={'keyring': ['keyring>=13.0.0']},
+                          'PyYaml>=3.12', 'future', 'PySocks>=1.6.7'],
+        extras_require={'keyring': ['keyring>=13.0.0'],
+                        'jsonschema': ['jsonschema==4.0.1']},
         setup_requires=["pytest-runner>=2.0,<3dev"],
-        tests_require=["pytest", "pytest-cov", "coverage>=4.4.2", "jsonschema"],
+        tests_require=["pytest", "pytest-cov", "coverage>=4.4.2", "jsonschema==4.0.1"],
         package_data={
             'caosdb': ['cert/indiscale.ca.crt', 'schema-pycaosdb-ini.yml'],
         },

tox.ini

@@ -7,4 +7,5 @@ deps = .
     nose
     pytest
     pytest-cov
+    jsonschema==4.0.1
 commands=py.test --cov=caosdb -vv {posargs}