[CI] Re-enable pylint for newer distributions and resolve warnings

Re-enabling pylint checks for distributions newer than Ubuntu 18.04.
This commit addresses the following pylint warnings:
- Ignored warnings for imports outside toplevel.
- Updated code to use `subprocess.run(check=True)` which
  raises an exception on non-zero return codes.

Signed-off-by: Mariusz Zaborski <oshogbo@invisiblethingslab.com>

.ci/lib/stage-lint.jenkinsfile

@@ -1,10 +1,7 @@
 stage('lint') {
     sh '''
         ./scripts/gitignore-check-files
-        if .ci/isdistro bionic
-        then
-            ./.ci/run-pylint -f text
-        fi
+        ./.ci/run-pylint -f text
         ./.ci/run-shellcheck
     '''
 }

libos/test/ltp/test_ltp.py

@@ -212,8 +212,9 @@ def test_ltp(cmd, section):
 
 def test_lint():
     cmd = ['./contrib/conf_lint.py', '--scenario', LTP_SCENARIO, *LTP_CONFIG]
-    p = subprocess.run(cmd)
-    if p.returncode:
+    try:
+        subprocess.run(cmd, check=True)
+    except subprocess.CalledProcessError:
         pytest.fail('conf_lint.py failed, see stdout for details')
 
 

python/gramine-sgx-get-token

@@ -13,7 +13,7 @@ from graminelibos import Sigstruct, get_token, is_oot
 @click.option('--verbose/--quiet', '-v/-q', default=True, help='Display details (on by default)')
 def main(sig, output, verbose):
     if not is_oot():
-        import warnings
+        import warnings # pylint: disable=import-outside-toplevel
         warnings.warn(
             'gramine-sgx-get-token is deprecated on upstream SGX driver, '
             'and calling it will be a hard error in the future',

python/graminelibos/sgx_get_token.py

@@ -50,7 +50,7 @@ def p64(x):
 def connect_aesmd(mrenclave, modulus, flags, xfrms):
     '''Connect with AESMD.'''
 
-    from . import aesm_pb2 # pylint: disable=import-error,no-name-in-module
+    from . import aesm_pb2 # pylint: disable=import-error,no-name-in-module,import-outside-toplevel
 
     req_msg = aesm_pb2.GetTokenReq()
     req_msg.req.signature = mrenclave