matlab-proxy now warns instead of erroring out when Xvfb is not found on Linux Systems.

* Makes Xvfb optional on Linux.
* Added infrastructure to display warnings on the status information modal.

fixes mathworks/jupyter-matlab-proxy#75

Author: diningPhilosopher64

README.md

@@ -47,9 +47,10 @@ The MATLAB Proxy is under active development. For support or to report issues, s
 
   $ sudo yum install xorg-x11-server-Xvfb
   ```
+  
+  *Note: The installation of Xvfb is **optional** (w.e.f. v0.11.0 of matlab-proxy). However, we highly recommend installing it.*
 * Python versions: **3.8** | **3.9**  | **3.10** | **3.11**
 * [Browser Requirements](https://www.mathworks.com/support/requirements/browser-requirements.html)
-
 * Supported Operating Systems:
     * Linux®
     * Windows® Operating System ( starting v0.4.0 of matlab-proxy )

gui/package.json

@@ -40,7 +40,7 @@
       "last 1 safari version"
     ]
   },
-  "proxy": "http://127.0.0.1:8000",
+  "proxy": "http://127.0.0.1:8888",
   "homepage": "./",
   "devDependencies": {
     "@babel/preset-env": "^7.11.0",

gui/src/components/Information/Information.css

@@ -1,6 +1,6 @@
 /* Copyright (c) 2020-2022 The MathWorks, Inc. */
 
-#information .alert:not(.error-container) {
+#information .alert:not(.error-container, .warnings-container) {
     padding: 0;
     margin-bottom: 0;
     background: white;
@@ -24,37 +24,39 @@
     margin-bottom: 0;
 }
 
-#information .error-msg {
+#information .error-msg, .warnings-msg {
     white-space: pre;
     font: 10pt monospace;
 }
 
-#information .error-container.alert {
+#information .error-container.alert, .warnings-container.alert {
     border-radius: 0;
     margin: 5px 20px;
     padding: 10px;
 }
 
-#information .error-container.alert p {
+#information .error-container.alert p, .warnings-container.alert p {
     margin: 0;
 }
 
-#information .error-container.alert .error-text {
+#information .error-container.alert .error-text,
+.warnings-container.alert .warnings-text {
     margin-left: 30px;
 }
 
-#information .error-logs-container .error-container.alert {
+#information .error-logs-container .error-container.alert, 
+.warnings-container .warnings-container.alert {
     padding: 0;
     /* if this is inside an expand-collapse, padding just gets in the way */
 }
 
-#information .error-msg {
+#information .error-msg, .warnings-msg {
     padding: 10px;
     max-height: 200px;
     overflow: auto;
 }
 
-#information .error-logs-container .expand_trigger {
+#information .error-logs-container .warnings-container .expand_trigger {
     padding: 10px 5px 5px 40px;
     font-size: 15px;
 }
@@ -156,4 +158,4 @@
     padding-top: 5px;
     padding-bottom: 0.3em;
     max-width: 10ch;
-}
+}

gui/src/components/Information/index.js

@@ -7,6 +7,7 @@ import Linkify from 'react-linkify';
 import {
     selectLicensingInfo,
     selectError,
+    selectWarnings,
     selectOverlayHidable,
     selectInformationDetails,
     selectAuthEnabled,
@@ -22,6 +23,7 @@ function Information({
 }) {
     const licensingInfo = useSelector(selectLicensingInfo);
     const error = useSelector(selectError);
+    const warnings = useSelector(selectWarnings);
     const overlayHidable = useSelector(selectOverlayHidable);
 
     const [token, setToken] = useState('');
@@ -33,9 +35,7 @@ function Information({
     const tokenInput = useRef();
 
     const [errorLogsExpanded, setErrorLogsExpanded] = useState(false);
-    const errorLogsExpandedToggle = () => {
-        setErrorLogsExpanded(!errorLogsExpanded);
-    };
+    const [warningsExpanded, setWarningsExpanded] = useState(true);
 
     let info;
     switch (licensingInfo?.type) {
@@ -73,8 +73,8 @@ function Information({
 
     const errorLogsNode = (error && error.logs !== null && error.logs.length > 0) ? (
         <div className="expand_collapse error-logs-container">
-            <h4 className={`expand_trigger ${errorLogsExpanded ? 'expanded' : 'collapsed'}`}
-                onClick={errorLogsExpandedToggle}>
+            <h4 className={`expand_trigger ${errorLogsExpanded ? 'expanded' : 'collapsed'}`} 
+            onClick={() => setErrorLogsExpanded(!errorLogsExpanded)}>
                 <span className="icon-arrow-open-down"></span>
                 <span className="icon-arrow-open-right"></span>
                 Error logs
@@ -89,6 +89,31 @@ function Information({
         </div>
     ) : null;
 
+    const linkDecorator = (href, text, key) => (
+            <a href={href} key={key} target="_blank" rel="noopener noreferrer">
+                {text}
+            </a>
+        );
+
+
+    const warningsNode = (warnings && warnings.length > 0) ? (
+        <div className="expand_collapse warnings-container">
+            <h4 className={`expand_trigger ${warningsExpanded ? 'expanded' : 'collapsed'}`}
+                onClick={() => setWarningsExpanded(!warningsExpanded)}>
+                <span className="icon-arrow-open-down"></span>
+                <span className="icon-arrow-open-right"></span>
+                Warnings
+            </h4>
+            <div id="warnings"
+                className={`expand_target warnings-container alert alert-warning ${warningsExpanded ? 'expanded' : 'collapsed'}`}
+                aria-expanded={warningsExpanded}>
+                <Linkify componentDecorator={linkDecorator}>
+                    <div className="warnings-msg">{warnings.map((warning, index) => (index + 1).toString() + ")" + warning.trim()).join("\n\n")}</div>
+                </Linkify>
+            </div>
+        </div>
+    ) : null;
+
     const onCloseClick = event => {
         if (event.target === event.currentTarget) {
             event.preventDefault();
@@ -197,6 +222,7 @@ function Information({
                         </div>
                         {errorMessageNode}
                         {errorLogsNode}
+                        {warningsNode}
                     </div>
                     <div className="modal-footer">
                         {children}

gui/src/reducers/index.js

@@ -253,6 +253,16 @@ export function loadUrl(state = null, action) {
     }
 }
 
+export function warnings(state = null, action) {
+    switch (action.type) {
+        case RECEIVE_SERVER_STATUS:
+            const warnings = action.status.warnings;                             
+            return warnings.length > 0 ? warnings : null;
+        default:
+            return state;
+    }
+}
+
 export function error(state = null, action) {
     switch (action.type) {
         case SET_AUTH_STATUS:
@@ -328,6 +338,7 @@ export default combineReducers({
     serverStatus,
     loadUrl,
     error,
+    warnings,
     envConfig,
     useMOS,
     useMRE,

gui/src/selectors/index.js

@@ -15,6 +15,7 @@ export const selectLicensingInfo = state => state.serverStatus.licensingInfo;
 export const selectServerStatusFetchFailCount = state => state.serverStatus.fetchFailCount;
 export const selectLoadUrl = state => state.loadUrl;
 export const selectError = state => state.error;
+export const selectWarnings = state => state.warnings;
 export const selectUseMOS = state => state.useMOS === true;
 export const selectUseMRE = state => state.useMRE === true;
 export const selectAuthEnabled = state => state.authentication.enabled;

matlab_proxy/app.py

@@ -113,6 +113,7 @@ async def create_status_response(app, loadUrl=None):
             "licensing": marshal_licensing_info(state.licensing),
             "loadUrl": loadUrl,
             "error": marshal_error(state.error),
+            "warnings": state.warnings,
             "wsEnv": state.settings.get("ws_env", ""),
         }
     )

matlab_proxy/app_state.py

@@ -84,6 +84,7 @@ def __init__(self, settings):
 
         # Initialize with the error state from the initialization of settings
         self.error = settings["error"]
+        self.warnings = settings["warnings"]
 
         if self.error is not None:
             self.logs["matlab"].clear()
@@ -262,7 +263,10 @@ def _are_required_processes_ready(
             xvfb_process = self.processes["xvfb"]
 
         if system.is_linux():
-            if xvfb_process is None or xvfb_process.returncode is not None:
+            # If Xvfb is on system PATH, check if it up and running.
+            if self.settings["is_xvfb_available"] and (
+                xvfb_process is None or xvfb_process.returncode is not None
+            ):
                 logger.debug(
                     "Xvfb has not started"
                     if xvfb_process is None
@@ -671,9 +675,22 @@ async def __setup_env_for_matlab(self) -> dict:
         # DDUX info for MATLAB
         matlab_env["MW_CONTEXT_TAGS"] = self.settings.get("mw_context_tags")
 
+        # Update DISPLAY env variable for MATLAB only if it was supplied by Xvfb.
         if system.is_linux():
-            # Adding DISPLAY key which is only available after starting Xvfb successfully.
-            matlab_env["DISPLAY"] = self.settings["matlab_display"]
+            if self.settings.get("matlab_display", None):
+                matlab_env["DISPLAY"] = self.settings["matlab_display"]
+                logger.info(
+                    f"Using the display number supplied by Xvfb process:{matlab_env['DISPLAY']} for launching MATLAB"
+                )
+            else:
+                if "DISPLAY" in matlab_env:
+                    logger.info(
+                        f"Using the existing DISPLAY environment variable with value:{matlab_env['DISPLAY']} for launching MATLAB"
+                    )
+                else:
+                    logger.info(
+                        "No DISPLAY environment variable found. Launching MATLAB without it."
+                    )
 
         # The matlab ready file is written into this location(self.mwi_logs_dir) by MATLAB
         # The mwi_logs_dir is where MATLAB will write any subsequent logs
@@ -968,8 +985,8 @@ async def start_matlab(self, restart_matlab=False):
         self.error = None
         self.logs["matlab"].clear()
 
-        # Start Xvfb process if in a posix system
-        if system.is_linux():
+        # Start Xvfb process on linux if possible
+        if system.is_linux() and self.settings["is_xvfb_available"]:
             xvfb = await self.__start_xvfb_process()
 
             # xvfb variable would be None if creation of the process failed.

matlab_proxy/settings.py

@@ -199,6 +199,8 @@ def get_dev_settings(config):
         "mwi_use_existing_license": mwi.validators.validate_use_existing_licensing(
             os.getenv(mwi_env.get_env_name_mwi_use_existing_license(), "")
         ),
+        "warnings": [],
+        "is_xvfb_available": False,
     }
 
 
@@ -243,13 +245,21 @@ def get(config_name=matlab_proxy.get_default_config_name(), dev=False):
             settings["nlm_conn_str"] = "123@nlm"
 
     else:
-        settings = {"error": None}
+        settings = {"error": None, "warnings": []}
 
         # Initializing server settings separately allows us to return
         # a minimal set of settings required to launch the server even if
         # there is an exception thrown when creating the matlab specific settings.
         settings.update(get_server_settings(config_name))
 
+        settings["is_xvfb_available"] = True if shutil.which("Xvfb") else False
+
+        # Warn user if xvfb is not available on system path.
+        if system.is_linux() and not settings["is_xvfb_available"]:
+            warning = " Unable to find Xvfb on the system PATH. Xvfb enables graphical abilities like plots and figures in the MATLAB desktop.\nConsider adding Xvfb to the system PATH and restart matlab-proxy. See https://github.com/mathworks/matlab-proxy#requirements for information."
+            logger.warning(warning)
+            settings["warnings"].append(warning)
+
         try:
             # Update settings with matlab specific values.
             settings.update(get_matlab_settings())