[PLAT-20717]Collect File API does not show failed nodes when they are unreachable

Summary: Add a connectivity check before any of the file-collections/run-script APIs. Add a runtime config to configure this timeout

Test Plan:
```
curl -X POST "http://localhost:9000/api/v2/customers/<>/universes/<>/run-script"   -H "Content-Type: application/json"   -H "X-AUTH-YW-API-TOKEN: <>"   -d '{
>     "script_options": {
>       "script_content": "echo TEST_INLINE; echo COUNT=$#; echo ARG1=$1; echo ARG2=$2; echo ALL=$@",
>       "params": ["hello", "world"],
>       "timeout_secs": 30
>     }
>   }'
```
```
{"summary":{"total_nodes":3,"successful_nodes":2,"failed_nodes":1,"total_execution_time_ms":27667,"all_succeeded":false},"results":{"yb-admin-dkumar-1-n1":{"node_name":"yb-admin-dkumar-1-n1","node_address":"<>","exit_code":0,"stdout":"Command output:TEST_INLINE\nCOUNT=2\nARG1=hello\nARG2=world\nALL=hello world\n","execution_time_ms":127,"success":true},"yb-admin-dkumar-1-n2":{"node_name":"yb-admin-dkumar-1-n2","node_address":"<>","exit_code":-1,"stdout":"","execution_time_ms":27665,"success":false,"error_message":"Node is unreachable"},"yb-admin-dkumar-1-n3":{"node_name":"yb-admin-dkumar-1-n3","node_address":"<>","exit_code":0,"stdout":"Command output:TEST_INLINE\nCOUNT=2\nARG1=hello\nARG2=world\nALL=hello world\n","execution_time_ms":133,"success":true}}}
```

Reviewers: rajiv.kumar, nsingh, anabaria

Reviewed By: anabaria

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D53021

Author: Deepti-yb

managed/RUNTIME-FLAGS.md

@@ -135,6 +135,7 @@
 | "OIDC feature enhancements" | "yb.security.oidc_feature_enhancements" | "GLOBAL" | "Enables the OIDC enhancements such as auth_token retrieval, user registration in YBA on login, etc." | "Boolean" |
 | "Devops command timeout" | "yb.devops.command_timeout" | "GLOBAL" | "Devops command timeout" | "Duration" |
 | "Node destroy command timeout" | "yb.node_ops.destroy_server_timeout" | "GLOBAL" | "Timeout for node destroy command before failing." | "Duration" |
+| "Node reachability check timeout" | "yb.node_script.reachability_check_timeout_sec" | "GLOBAL" | "Timeout in seconds for the pre-check that determines whether a node is reachable for per-node platform APIs such as run-script and file-collections. Unreachable nodes are reported as failed nodes rather than producing per-file/per-command errors." | "Integer" |
 | "YBC Compatible DB Version" | "ybc.compatible_db_version" | "GLOBAL" | "Minimum YBDB version which supports YBC" | "String" |
 | "Force YBC Shutdown during upgrade" | "ybc.upgrade.force_shutdown" | "GLOBAL" | "For YBC Shutdown during upgrade" | "Boolean" |
 | "Enable strict mode to ignore deprecated YBA APIs" | "yb.api.mode.strict" | "GLOBAL" | "Will ignore deprecated APIs" | "Boolean" |

managed/src/main/java/com/yugabyte/yw/common/FileCollectionDownloader.java

@@ -427,6 +427,16 @@ private boolean cleanupNodeTarFile(Universe universe, NodeDetails node, String r
         return false;
       }
 
+      // Fail fast on unreachable nodes; otherwise rm-over-SSH will burn the full cleanup timeout
+      // and surface as a generic "failed to clean up" instead of "node unreachable".
+      if (!nodeUniverseManager.isNodeReachable(node, universe)) {
+        log.warn(
+            "Node {} is unreachable, skipping remote tar cleanup at {}",
+            node.nodeName,
+            remoteTarPath);
+        return false;
+      }
+
       nodeUniverseManager.runCommand(
           node, universe, List.of("rm", "-f", remoteTarPath), ShellProcessContext.DEFAULT);
       log.info("Cleaned up remote tar file {} on node {}", remoteTarPath, node.nodeName);
@@ -505,6 +515,18 @@ private NodeDownloadResult downloadFromNode(
             .build();
       }
 
+      // Fail fast on unreachable nodes; otherwise the per-node probes below swallow the
+      // connection error and surface as a misleading "Remote tar file not found".
+      if (!nodeUniverseManager.isNodeReachable(node, universe)) {
+        return NodeDownloadResult.builder()
+            .nodeName(node.nodeName)
+            .nodeAddress(node.cloudInfo.private_ip)
+            .success(false)
+            .errorMessage("Node is unreachable")
+            .downloadTimeMs(System.currentTimeMillis() - startTime)
+            .build();
+      }
+
       // Check if remote file exists
       if (!nodeUniverseManager.checkNodeIfFileExists(node, universe, remoteTarPath)) {
         return NodeDownloadResult.builder()

managed/src/main/java/com/yugabyte/yw/common/NodeFileCollector.java

@@ -247,6 +247,24 @@ private NodeResult collectFromNode(Universe universe, NodeDetails node, Collecti
     int failed = 0;
     long bytesCollected = 0;
 
+    // Fail fast on unreachable nodes; otherwise per-file probes swallow the
+    // connection error and the node is mis-reported as successful with file-level failures.
+    if (!nodeUniverseManager.isNodeReachable(node, universe)) {
+      long executionTime = System.currentTimeMillis() - nodeStartTime;
+      return NodeResult.builder()
+          .nodeName(node.nodeName)
+          .nodeAddress(node.cloudInfo.private_ip)
+          .success(false)
+          .filesCollected(0)
+          .filesSkipped(0)
+          .filesFailed(0)
+          .totalBytesCollected(0)
+          .executionTimeMs(executionTime)
+          .errorMessage("Node is unreachable")
+          .files(new ArrayList<>())
+          .build();
+    }
+
     try {
       // Collect all file paths to tar
       List<String> filesToCollect = new ArrayList<>();

managed/src/main/java/com/yugabyte/yw/common/NodeScriptRunner.java

@@ -178,6 +178,19 @@ public ExecutionResult runScript(
   private NodeResult executeOnNode(Universe universe, NodeDetails node, ScriptParams scriptParams) {
     long nodeStartTime = System.currentTimeMillis();
 
+    if (!nodeUniverseManager.isNodeReachable(node, universe)) {
+      long executionTime = System.currentTimeMillis() - nodeStartTime;
+      return NodeResult.builder()
+          .nodeName(node.nodeName)
+          .nodeAddress(node.cloudInfo.private_ip)
+          .exitCode(-1)
+          .stdout("")
+          .errorMessage("Node is unreachable")
+          .executionTimeMs(executionTime)
+          .success(false)
+          .build();
+    }
+
     try {
       ShellProcessContext.ShellProcessContextBuilder contextBuilder =
           ShellProcessContext.builder()

managed/src/main/java/com/yugabyte/yw/common/NodeUniverseManager.java

@@ -801,6 +801,17 @@ public boolean isNodeReachable(NodeDetails node, Universe universe, long timeout
     return false;
   }
 
+  /**
+   * Reachability pre-check for per-node platform APIs (run-script, file-collections, ...) that uses
+   * the shared {@code yb.node_script.reachability_check_timeout_sec} runtime flag so a single knob
+   * controls the timeout across all callers.
+   */
+  public boolean isNodeReachable(NodeDetails node, Universe universe) {
+    long timeoutSecs =
+        confGetter.getGlobalConf(GlobalConfKeys.nodeScriptReachabilityCheckTimeoutSec);
+    return isNodeReachable(node, universe, timeoutSecs);
+  }
+
   /**
    * Gets a map of all the absolute file paths to sizes at a given remote directory
    *

managed/src/main/java/com/yugabyte/yw/common/config/GlobalConfKeys.java

@@ -1191,6 +1191,17 @@ public class GlobalConfKeys extends RuntimeConfigKeysModule {
           "Timeout for node destroy command before failing.",
           ConfDataType.DurationType,
           ImmutableList.of(ConfKeyTags.PUBLIC));
+  public static final ConfKeyInfo<Integer> nodeScriptReachabilityCheckTimeoutSec =
+      new ConfKeyInfo<>(
+          "yb.node_script.reachability_check_timeout_sec",
+          ScopeType.GLOBAL,
+          "Node reachability check timeout",
+          "Timeout in seconds for the pre-check that determines whether a node is reachable for"
+              + " per-node platform APIs such as run-script and file-collections. Unreachable"
+              + " nodes are reported as failed nodes rather than producing per-file/per-command"
+              + " errors.",
+          ConfDataType.IntegerType,
+          ImmutableList.of(ConfKeyTags.PUBLIC));
   public static final ConfKeyInfo<String> ybcCompatibleDbVersion =
       new ConfKeyInfo<>(
           "ybc.compatible_db_version",

managed/src/main/resources/reference.conf

@@ -1556,6 +1556,7 @@ yb {
 
   node_script {
     enabled = false
+    reachability_check_timeout_sec = 30
   }
 
   gflags {