Correct format for JSONRPC for Clangd

I am attempting to send JSON to Clangd on my desktop using Python. I see in the terminal window that Clangd says:

I[15:52:46.580] Warning: Missing Content-Length header, or zero-length message.
"Content-Length": 53

{
    "jsonrpc": "2.0", 
    "id": 1, 
    "method": "exit"
} 

But that is not the case. Python code:

import argparse
import sys

if __name__ == "__main__":
    
    parser = argparse.ArgumentParser()
    parser.add_argument("-p", "--process_num", type=int, help="Clangd process number", required=True)
    parser.add_argument("-d", "--dry_run", action="store_true", help="Dry run")
    
    args = parser.parse_args()
    
    filepath = f"/proc/{args.process_num}/fd/0"
    
    my_content = """\
"Content-Length": 53

{
    "jsonrpc": "2.0", 
    "id": 1, 
    "method": "exit"
}"""
    
    if args.dry_run:
        print(my_content.encode("utf-8"))
        sys.exit(0)
    
    with open(filepath, 'wb') as f:
        f.write(my_content.encode("utf-8"))

Is there something in the formatting I am missing?

Answer

You're not supposed to quote the "Content-Length" , just send Content-Length: 53

Make sure you're using \r\n for the newlines too in the header part, as shown in the Language Server Protocol . Make sure your Content-Length is right as well, the json you posted here isn't 53 bytes,