Add 'status' command to get server status (#5197)

Example:


```
$ langchain plus start --expose
...
$ langchain plus status
The LangChainPlus server is currently running.

Service             Status         Published Ports
langchain-backend   Up 40 seconds  1984
langchain-db        Up 41 seconds  5433
langchain-frontend  Up 40 seconds  80
ngrok               Up 41 seconds  4040

To connect, set the following environment variables in your LangChain application:
LANGCHAIN_TRACING_V2=true
LANGCHAIN_ENDPOINT=https://5cef-70-23-89-158.ngrok.io

$ langchain plus stop
$ langchain plus status
The LangChainPlus server is not running.
$ langchain plus start
The LangChainPlus server is currently running.

Service             Status        Published Ports
langchain-backend   Up 5 seconds  1984
langchain-db        Up 6 seconds  5433
langchain-frontend  Up 5 seconds  80

To connect, set the following environment variables in your LangChain application:
LANGCHAIN_TRACING_V2=true
LANGCHAIN_ENDPOINT=http://localhost:1984
```

langchain/cli/main.py

@@ -1,4 +1,5 @@
 import argparse
+import json
 import logging
 import os
 import shutil
@@ -6,7 +7,7 @@ import subprocess
 from contextlib import contextmanager
 from pathlib import Path
 from subprocess import CalledProcessError
-from typing import Generator, List, Optional
+from typing import Dict, Generator, List, Mapping, Optional, Union, cast
 
 import requests
 import yaml
@@ -19,6 +20,50 @@ logger = logging.getLogger(__name__)
 _DIR = Path(__file__).parent
 
 
+def pprint_services(services_status: List[Mapping[str, Union[str, List[str]]]]) -> None:
+    # Loop through and collect Service, State, and Publishers["PublishedPorts"]
+    # for each service
+    services = []
+    for service in services_status:
+        service_status: Dict[str, str] = {
+            "Service": str(service["Service"]),
+            "Status": str(service["Status"]),
+        }
+        publishers = cast(List[Dict], service.get("Publishers", []))
+        if publishers:
+            service_status["PublishedPorts"] = ", ".join(
+                [str(publisher["PublishedPort"]) for publisher in publishers]
+            )
+        services.append(service_status)
+
+    max_service_len = max(len(service["Service"]) for service in services)
+    max_state_len = max(len(service["Status"]) for service in services)
+    service_message = [
+        "\n"
+        + "Service".ljust(max_service_len + 2)
+        + "Status".ljust(max_state_len + 2)
+        + "Published Ports"
+    ]
+    for service in services:
+        service_str = service["Service"].ljust(max_service_len + 2)
+        state_str = service["Status"].ljust(max_state_len + 2)
+        ports_str = service.get("PublishedPorts", "")
+        service_message.append(service_str + state_str + ports_str)
+
+    langchain_endpoint: str = "http://localhost:1984"
+    used_ngrok = any(["ngrok" in service["Service"] for service in services])
+    if used_ngrok:
+        langchain_endpoint = get_ngrok_url(auth_token=None)
+
+    service_message.append(
+        "\nTo connect, set the following environment variables"
+        " in your LangChain application:"
+        "\nLANGCHAIN_TRACING_V2=true"
+        f"\nLANGCHAIN_ENDPOINT={langchain_endpoint}"
+    )
+    logger.info("\n".join(service_message))
+
+
 def get_docker_compose_command() -> List[str]:
     """Get the correct docker compose command for this system."""
     try:
@@ -222,6 +267,36 @@ class PlusCommand:
             ]
         )
 
+    def status(self) -> None:
+        """Provide information about the status LangChainPlus server."""
+
+        command = [
+            *self.docker_compose_command,
+            "-f",
+            str(self.docker_compose_file),
+            "ps",
+            "--format",
+            "json",
+        ]
+
+        result = subprocess.run(
+            command,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+        )
+        try:
+            command_stdout = result.stdout.decode("utf-8")
+            services_status = json.loads(command_stdout)
+        except json.JSONDecodeError:
+            logger.error("Error checking LangChainPlus server status.")
+            return
+        if services_status:
+            logger.info("The LangChainPlus server is currently running.")
+            pprint_services(services_status)
+        else:
+            logger.info("The LangChainPlus server is not running.")
+            return
+
 
 def env() -> None:
     """Print the runtime environment information."""
@@ -284,7 +359,10 @@ def main() -> None:
         "logs", description="Show the LangChainPlus server logs."
     )
     server_logs_parser.set_defaults(func=lambda args: server_command.logs())
-
+    server_status_parser = server_subparsers.add_parser(
+        "status", description="Show the LangChainPlus server status."
+    )
+    server_status_parser.set_defaults(func=lambda args: server_command.status())
     env_parser = subparsers.add_parser("env")
     env_parser.set_defaults(func=lambda args: env())