[backport 9.4] aspire exec fixes (#10628)

* chore: `aspire exec --help` improvements (#10598)

* provide more info in help

* rsc changes

* typo

* include COMMAND LINE to be explicit

* with examples

* fix: `aspire exec` fail fast improvements (#10606)

* fix aot (#10625)

* fix build

Author: DeagleGross

src/Aspire.Cli/Commands/ExecCommand.cs

@@ -67,6 +67,11 @@ public ExecCommand(
         startResourceOption.Description = ExecCommandStrings.StartTargetResourceArgumentDescription;
         Options.Add(startResourceOption);
 
+        // only for --help output
+        var commandOption = new Option<string>("--");
+        commandOption.Description = ExecCommandStrings.CommandArgumentDescription;
+        Options.Add(commandOption);
+
         TreatUnmatchedTokensAsErrors = false;
     }
 
@@ -78,6 +83,37 @@ protected override async Task<int> ExecuteAsync(ParseResult parseResult, Cancell
             return ExitCodeConstants.SdkNotInstalled;
         }
 
+        // validate required arguments firstly to fail fast if not found
+        var targetResourceMode = "--resource";
+        var targetResource = parseResult.GetValue<string>("--resource");
+        if (string.IsNullOrEmpty(targetResource))
+        {
+            targetResourceMode = "--start-resource";
+            targetResource = parseResult.GetValue<string>("--start-resource");
+        }
+
+        if (targetResource is null)
+        {
+            _interactionService.DisplayError(ExecCommandStrings.TargetResourceNotSpecified);
+            return ExitCodeConstants.InvalidCommand;
+        }
+
+        // unmatched tokens are those which will be tried to parse as command.
+        // if none - we should fail fast
+        if (parseResult.UnmatchedTokens.Count == 0)
+        {
+            _interactionService.DisplayError(ExecCommandStrings.NoCommandSpecified);
+            return ExitCodeConstants.InvalidCommand;
+        }
+
+        var (arbitraryFlags, commandTokens) = ParseCmdArgs(parseResult);
+
+        if (commandTokens is null || commandTokens.Count == 0)
+        {
+            _interactionService.DisplayError(ExecCommandStrings.FailedToParseCommand);
+            return ExitCodeConstants.InvalidCommand;
+        }
+
         var buildOutputCollector = new OutputCollector();
         var runOutputCollector = new OutputCollector();
 
@@ -118,28 +154,6 @@ protected override async Task<int> ExecuteAsync(ParseResult parseResult, Cancell
                 StandardErrorCallback = runOutputCollector.AppendError,
             };
 
-            var targetResourceMode = "--resource";
-            var targetResource = parseResult.GetValue<string>("--resource");
-            if (string.IsNullOrEmpty(targetResource))
-            {
-                targetResourceMode = "--start-resource";
-                targetResource = parseResult.GetValue<string>("--start-resource");
-            }
-
-            if (targetResource is null)
-            {
-                _interactionService.DisplayError(ExecCommandStrings.TargetResourceNotSpecified);
-                return ExitCodeConstants.InvalidCommand;
-            }
-
-            var (arbitraryFlags, commandTokens) = ParseCmdArgs(parseResult);
-
-            if (commandTokens is null || commandTokens.Count == 0)
-            {
-                _interactionService.DisplayError(ExecCommandStrings.FailedToParseCommand);
-                return ExitCodeConstants.InvalidCommand;
-            }
-
             string[] args = [
                 "--operation", "run",
                 targetResourceMode, targetResource!,

src/Aspire.Cli/Resources/ExecCommandStrings.Designer.cs

@@ -118,21 +118,33 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="Description" xml:space="preserve">
-    <value>Run an Aspire app host to execute a command against the resource. (Preview)</value>
+    <value>Execute commands in the context of an Aspire application resource. Starts the AppHost, waits for resources to initialize, then runs the specified command in the target resource's environment. (Preview)
+
+Examples:
+  aspire exec --resource api dotnet build
+  aspire exec --resource api -- dotnet test --logger console
+  aspire exec --start-resource worker pwsh -c "Get-Process"
+    </value>
   </data>
   <data name="ProjectArgumentDescription" xml:space="preserve">
-    <value>The path to the Aspire app host project file.</value>
+    <value>The path to the Aspire AppHost project file. If not specified, searches for a project file in the current directory.</value>
   </data>
   <data name="StartTargetResourceArgumentDescription" xml:space="preserve">
-    <value>The name of the target resource to start and execute the command against.</value>
+    <value>The name of the target resource to execute the command against. The command will only be executed after the target resource has successfully started and is running.</value>
   </data>
   <data name="TargetResourceArgumentDescription" xml:space="preserve">
-    <value>The name of the target resource to execute the command against.</value>
+    <value>The name of the target resource to execute the command against. The command will be executed as soon as the AppHost starts, without waiting for the resource to be ready.</value>
   </data>
   <data name="TargetResourceNotSpecified" xml:space="preserve">
-    <value>Target resource is not specified.</value>
+    <value>Target resource is not specified. Use --resource or --start-resource to specify the target.</value>
   </data>
   <data name="FailedToParseCommand" xml:space="preserve">
-    <value>Failed to parse command.</value>
+    <value>Failed to parse the command. Ensure the command is specified after all options or after the -- separator.</value>
+  </data>
+  <data name="CommandArgumentDescription" xml:space="preserve">
+    <value>The command to execute in the target resource's context. Commands can be specified directly after options or after a -- separator.</value>
+  </data>
+  <data name="NoCommandSpecified" xml:space="preserve">
+    <value>Command is not specified.</value>
   </data>
-</root>
+</root>