Differences

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--- simple-bpq-telnet-application [2024/11/28 17:20] – [Configuring this as a service] kc2ihx
+++ simple-bpq-telnet-application [2026/02/21 20:23] (current) – [Program Code] kc2ihx
@@ Line 1: / Line 1: @@
 ====== Creating a simple BPQ Application ======
 This tutorial shows you how to set up a simple python script [[https://www.cantab.net/users/john.wiseman/Documents/LinBPQ%20Applications%20Interface.html|connected to linbpq as a telnet application]].
+In order to do this we'll do the following:
+  - Create a location for the script, data, and a python ''venv''
+  - Write the script
+  - Add the application to ''BPQ32.cfg''
+  - Setup a ''systemd'' service to keep it running.
+===== Setup =====
+To organize this project, I created a python virtual environment called ''bpq-apps'' in my ''.local'' directory, and installed the ''telnetlib3'' module that it depends on.  Within the ''bpq-apps'' virtual environment directory, I also created a folder called scripts and a folder called data.  I'm going to install various small BPQ applications here.
+I'm using the python virtual environment framework to help manage the various dependencies I might want to use for these scripts.
+<code>
+$ cd ~/.local
+$ python -m venv bpq-apps
+$ cd ./bpq-apps
+$ mkdir scripts data
+$ source ./bin/activate
+(bpq-apps)$ pip install telnetlib3
+</code>
 ===== Writing the program =====
 I chose to write this in Python to be a //little// more clear than the Perl application provided in the link above.
-This program, called ''ROLL'' uses a file called ''messages.json'' to provide it a welcome message and the blocks of text.
+The BPQ Application, called ''ROLL'' uses a file called ''messages.json'' to provide it a welcome message and the blocks of text.  The script itself was placed under the ''scripts'' directory created above, saved as ''rick.py''
-I saved both of these to ''~/.local/bpq-apps/roll''
 ==== Program Code ====
@@ Line 13: / Line 31: @@
 <code>
-import asyncio, telnetlib3, json
+import asyncio, telnetlib3, json, sys
 from optparse import OptionParser
+# this sets up the command line options, primarily the file to read and the port to open for BPQ
 parser = OptionParser()
 parser.add_option("-f", "--file", dest="filename", help="which json file with message and welcome", metavar="FILE")
@@ Line 21: / Line 40: @@
 (options, args) = parser.parse_args()
+# read file with messages
 messages = json.load(open(options.filename,'r'))
+# logging method to write to stderr for journalctl to pick up
+def print_log(*a):
+    print(*a, file=sys.stderr)
+# this is the main function that processes input from user and writes outputs
 async def shell(reader, writer):
+    # first thing provided is user's callsign
     incall = await reader.readline()
-    print("%s connected" % incall)
+    print_log("%s connected" % incall)
     writer.write("\r\nWelcome %s" % incall)
     writer.write("\r\n%s" % messages["welcome"])
+    # make copy of blocks so we can pop 'em
     textblocks = messages["text"].copy()
+    # don't let them leave until they've been rolled
+    leave = False
+    rolled = False
+    # take first input from user after welcome message
     inp = await reader.readline()
-    leave = inp[0].upper() in ["Q", "B"]
+    text_count = 0
+    incall = incall.rstrip()
+    # loop on inputs until they leave
     while inp and not leave and len(textblocks) > 0:
-        print("writing next block")
+        writer.write(textblocks.pop(0))
-        writer.write(textblocks.pop())
         await writer.drain()
         inp = await reader.readline()
-        leave = inp[0].upper() in ["Q", "B"]
+        text_count += 1
+        if not rolled:
+            # log that rolling has happened
+            print_log("%s rickrolled" % incall)
+            rolled = True
+        # if they type something starting with Q or B (quit, bye, bye-bye, etc.) let them leave
+        leave = inp[0].upper() in ["Q", "B"] and rolled
+        # log their input to journalctl via stderr
+        print_log("%s (%d): \"%s\"" % (incall, text_count, inp.rstrip()))
     writer.close()
+# sets up the async process to take inputs
 loop = asyncio.get_event_loop()
 coro = telnetlib3.create_server(port=options.port, shell=shell)
@@ Line 67: / Line 108: @@
 In my ''bpq32.cfg'' file, I added the port number to the telnet port, where the fourth entry, ''10001'' is the port for my new application:
 <code>
-CMDPORT=8005 63001 4565 10001
+CMDPORT=8005 63001 10001
 </code>
-and in the application list, I added a new entry, where ''3'' is the 0th-indexed 4th entry above.
+and in the application list, I added a new entry, where ''HOST 2'' is due to being the 0th-indexed 3rd entry above.
 <code>
-APPLICATION 4,ROLL,C 1 HOST 3 S
+APPLICATION 3,ROLL,C 1 HOST 2 S
 </code>
 ===== Configuring this as a service =====
 Next we'll configure a ''systemd'' service to make sure this script is always running and ready to accept connections.
-//todo write block describing adding a service to run this script//
+Put this file in ''/etc/systemd/system/rick.service'':
+<code>
+# service for RRoAX25 server
+# replace USER with the username under which you created the bpq-apps venv
+[Unit]
+Description="RRoAX25 service"
+After=network.target
+# this might be backwards, but I do need linbpq for this to work.
+Requires=linbpq.service
+[Service]
+Type=simple
+User=evan
+Group=evan
+WorkingDirectory=/home/USER/.local/bpq-apps/
+ExecStart=/home/USER/.local/bpq-apps/bin/python /home/USER/.local/bpq-apps/scripts/rick.py -p 10001 -f /home/USER/.local/bpq-apps/data/messages.json
+Restart=always
+RestartSec=3
+[Install]
+WantedBy=default.target
+</code>
+Activate it by running:
+<code>
+sudo systemctl enable rick.service
+sudo systemctl start rick.service
+</code>
+Then check the status to confirm it is working:
+<code>
+systemctl status rick.service
+</code>
+If you need to edit the service file, reload it with:
+<code>
+systemctl daemon-reload
+</code>
+Finally, to see who has used it:
+<code>
+journalctl -u rick.service -f
+</code>