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I've bought my first Raspberry Pi 3B+ last week and started working on my project but I seem to be stuck at this point. I've looked through a hundred different posts but none of the solutions seem to work for me.

Brief info on what I'm trying to accomplish: A python script the listens for button presses needs to be started at boot (regardless of if I'm booting in headless mode or full desktop) and needs to be able to control MPD playback (python-mpd2)

I've tried: - adding 'python /home/pi/Documents/Jukebox/Listener.py' to /etc/rc.local while enabling rc.local and making it executable - creating a service 'listener.service' in the /etc/systemd/system/ folder with the following code:

[Unit]
Description=start listening to button presses
Wants=network-online.target
After=network-online.target

[Service]
Type=simple
User=pi
WorkingDirectory=/home/pi
ExecStart=/home/pi/Documents/Jukebox/Listener.py

[Install]
WantedBy=multi-user.target

My python script is very basic and just assign the GPIO inputs, listens to changes and executes a MPD command:

#!/usr/bin/python
import RPi.GPIO as GPIO
import mpd
import time
from toggleplayback import toggleplaypauze 
GPIO.setmode(GPIO.BCM)
GPIO.setup(17,GPIO.IN,pull_up_down = GPIO.PUD_DOWN)
GPIO.add_event_detect(17, GPIO.RISING, bouncetime = 200)
GPIO.setup(18,GPIO.IN,pull_up_down = GPIO.PUD_DOWN)
GPIO.add_event_detect(18, GPIO.RISING, bouncetime = 200)
GPIO.setup(20,GPIO.IN,pull_up_down = GPIO.PUD_DOWN)
GPIO.add_event_detect(20, GPIO.RISING, bouncetime = 200)
client = mpd.MPDClient()
client.connect("localhost",6600)

def toggleplayback(self):
    status=client.status()
    print(status['state'])
    if (status['state'] == "pause"):
        client.pause(0)
    elif (status['state'] == "stop"):
        client.play(1)
    else :
        client.pause(1)

def nextsong(self):
    client.next()

def previoussong(self):
    client.previous()


GPIO.add_event_callback(17,toggleplayback)
GPIO.add_event_callback(18,nextsong)
GPIO.add_event_callback(20,previoussong)

while True:
    time.sleep(0.01)

When I test the service by enabling it and starting it, it works perfectly. However, when I restart the service is not started by default and if I check the status of the service I get the following error:

pi@raspberrypi:~ $ systemctl status listener.service    
listener.service - start listening to button presses
       Loaded: loaded (/etc/systemd/system/listener.service; enabled; vendor preset: enabled)
       Active: failed (Result: exit-code) since Sun 2019-01-13 16:04:44 CET; 42s ago
      Process: 398 ExecStart=/home/pi/Documents/Jukebox/Listener.py (code=exited, status=1/FAILURE)
     Main PID: 398 (code=exited, status=1/FAILURE)

    jan 13 16:04:44 raspberrypi Listener.py[398]:   File "/home/pi/Documents/Jukebox/Listener.py", line 14, in <module>
    jan 13 16:04:44 raspberrypi Listener.py[398]:     client.connect("localhost",6600)
    jan 13 16:04:44 raspberrypi Listener.py[398]:   File "/home/pi/.local/lib/python2.7/site-packages/mpd/base.py", line 641, in connect
    jan 13 16:04:44 raspberrypi Listener.py[398]:     self._sock = self._connect_tcp(host, port)
    jan 13 16:04:44 raspberrypi Listener.py[398]:   File "/home/pi/.local/lib/python2.7/site-packages/mpd/base.py", line 604, in _connect_tcp
    jan 13 16:04:44 raspberrypi Listener.py[398]:     raise err
    jan 13 16:04:44 raspberrypi Listener.py[398]: socket.error: [Errno 111] Connection refused
    jan 13 16:04:44 raspberrypi systemd[1]: listener.service: Main process exited, code=exited, status=1/FAILURE
    jan 13 16:04:44 raspberrypi systemd[1]: listener.service: Unit entered failed state.
    jan 13 16:04:44 raspberrypi systemd[1]: listener.service: Failed with result 'exit-code'.

I'm now officially out of ideas on what to do. If anyone can give me a new idea or an explanation about why what I'm trying to do is wrong and how I should be doing this, please advise!

Thanks

  • Has the mpd daemon that your trying to connect started before your code starts? Try adding a sleep before the connect? – CoderMike Jan 13 at 16:24
  • Connection refused means one of two things 1. wrong IP address (port number may be right or wrong) or 2. right IP address, wrong port number. You're trying to connect to port 6600 - is there a listener on that port? Take a look with sudo netstat -tlnpu | grep 6600 – Dougie Jan 13 at 20:19
  • Thanks for the replies guys, I'll try some more tomorrow, was working on NFC this afternoon. @Dougie The script works fine when the system is fully booted though so the ip (localhost) and port should not be the problem. It might be that this script is loaded before the mpd daemon service is loaded but how would i go about changing the load order? – Revam Jan 13 at 23:02
  • If you're starting everything with systemd xxx.service files then you can put a Wants=xxx.service dependency so that your script starts after the mpd.service is running. – Dougie Jan 14 at 0:53
1

You should start your script After=mpd.service. I think it isn't needed to start After=network-online.target because this is already managed by the mpd.service. You can check it with systemctl cat mpd.service. You can also omit Type=simple because it's default. So I would suggest the following unit:

[Unit]
Description=start listening to button presses
After=mpd.service

[Service]
User=pi
WorkingDirectory=/home/pi
ExecStart=/home/pi/Documents/Jukebox/Listener.py

[Install]
WantedBy=multi-user.target
  • I finally got it to work a few days ago! Your suggestion did seem to do the trick except for some time when it didn't. It seems that while setting it after mpd.service does make it wait for that service to start loading, it does not wait until it is loaded and so I had to add a 3 second sleep time in my actual python script. This is the only thing that worked consistently. So also thanks to @CoderMike who's tip to use sleep helped me make this solution more consistent! – Revam Jan 23 at 21:52
-1

To me this looks like you haven't solved the MPD.conf which can be located elsewhere on your system. Mine is in /home/user/.config/mpd/mpd.conf

# An example configuration file for MPD.
# Read the user manual for documentation: http://www.musicpd.org/doc/user/


# Files and directories #######################################################
#
# This setting controls the top directory which MPD will search to discover the
# available audio files and add them to the daemon's online database. This 
# setting defaults to the XDG directory, otherwise the music directory will be
# be disabled and audio files will only be accepted over ipc socket (using
# file:// protocol) or streaming files over an accepted protocol.
#
music_directory     "~/Music"
#
# This setting sets the MPD internal playlist directory. The purpose of this
# directory is storage for playlists created by MPD. The server will use 
# playlist files not created by the server but only if they are in the MPD
# format. This setting defaults to playlist saving being disabled.
#
playlist_directory      "~/.config/mpd/playlists"
#
# This setting sets the location of the MPD database. This file is used to
# load the database at server start up and store the database while the 
# server is not up. This setting defaults to disabled which will allow
# MPD to accept files over ipc socket (using file:// protocol) or streaming
# files over an accepted protocol.
#
db_file         "~/.config/mpd/database"
# 
# These settings are the locations for the daemon log files for the daemon.
# These logs are great for troubleshooting, depending on your log_level
# settings.
#
# The special value "syslog" makes MPD use the local syslog daemon. This
# setting defaults to logging to syslog, otherwise logging is disabled.
#
log_file            "~/.config/mpd/log"
#
# This setting sets the location of the file which stores the process ID
# for use of mpd --kill and some init scripts. This setting is disabled by
# default and the pid file will not be stored.
#
pid_file            "~/.config/mpd/pid"
#
# This setting sets the location of the file which contains information about
# most variables to get MPD back into the same general shape it was in before
# it was brought down. This setting is disabled by default and the server 
# state will be reset on server start up.
#
state_file          "~/.config/mpd/state"
#
# The location of the sticker database.  This is a database which
# manages dynamic information attached to songs.
#
sticker_file            "~/.config/mpd/sticker.sql"
#
###############################################################################


# General music daemon options ################################################
#
# This setting specifies the user that MPD will run as. MPD should never run as
# root and you may use this setting to make MPD change its user ID after
# initialization. This setting is disabled by default and MPD is run as the
# current user.
#
#user               "nobody"
#
# This setting specifies the group that MPD will run as. If not specified
# primary group of user specified with "user" setting will be used (if set).
# This is useful if MPD needs to be a member of group such as "audio" to
# have permission to use sound card.
#
#group              "nogroup"
#
# This setting sets the address for the daemon to listen on. Careful attention
# should be paid if this is assigned to anything other then the default, any.
# This setting can deny access to control of the daemon. Not effective if
# systemd socket activiation is in use.
#
# For network
#bind_to_address        "any"
#
# And for Unix Socket
bind_to_address     "192.168.1.1"
#
# This setting is the TCP port that is desired for the daemon to get assigned
# to.
#
port                "6600"
#
# This setting controls the type of information which is logged. Available 
# setting arguments are "default", "secure" or "verbose". The "verbose" setting
# argument is recommended for troubleshooting, though can quickly stretch
# available resources on limited hardware storage.
#
#log_level          "default"
#
# If you have a problem with your MP3s ending abruptly it is recommended that 
# you set this argument to "no" to attempt to fix the problem. If this solves
# the problem, it is highly recommended to fix the MP3 files with vbrfix
# (available from <http://www.willwap.co.uk/Programs/vbrfix.php>), at which
# point gapless MP3 playback can be enabled.
#
#gapless_mp3_playback           "yes"
#
# Setting "restore_paused" to "yes" puts MPD into pause mode instead
# of starting playback after startup.
#
#restore_paused "no"
#
# This setting enables MPD to create playlists in a format usable by other
# music players.
#
#save_absolute_paths_in_playlists   "no"
#
# This setting defines a list of tag types that will be extracted during the
# audio file discovery process. The complete list of possible values can be
# found in the user manual.
#metadata_to_use    "artist,album,title,track,name,genre,date,composer,performer,disc"
#
# This setting enables automatic update of MPD's database when files in 
# music_directory are changed.
#
auto_update "yes"
#
# Limit the depth of the directories being watched, 0 means only watch
# the music directory itself.  There is no limit by default.
#
#auto_update_depth "3"
#
###############################################################################


# Symbolic link behavior ######################################################
#
# If this setting is set to "yes", MPD will discover audio files by following 
# symbolic links outside of the configured music_directory.
#
#follow_outside_symlinks    "yes"
#
# If this setting is set to "yes", MPD will discover audio files by following
# symbolic links inside of the configured music_directory.
#
#follow_inside_symlinks     "yes"
#
###############################################################################


# Zeroconf / Avahi Service Discovery ##########################################
#
# If this setting is set to "yes", service information will be published with
# Zeroconf / Avahi.
#
#zeroconf_enabled       "yes"
#
# The argument to this setting will be the Zeroconf / Avahi unique name for
# this MPD server on the network.
#
#zeroconf_name          "Music Player"
#
###############################################################################


# Permissions #################################################################
#
# If this setting is set, MPD will require password authorization. The password
# setting can be specified multiple times for different password profiles.
#
#password                        "password@read,add,control,admin"
#
# This setting specifies the permissions a user has who has not yet logged in. 
#
#default_permissions             "read,add,control,admin"
#
###############################################################################


# Database #######################################################################
#

#database {
#       plugin "proxy"
#       host "other.mpd.host"
#       port "6600"
#}

# Input #######################################################################
#

input {
        plugin "curl"
#       proxy "proxy.isp.com:8080"
#       proxy_user "user"
#       proxy_password "password"
}

#
###############################################################################

# Audio Output ################################################################
#
# MPD supports various audio output types, as well as playing through multiple 
# audio outputs at the same time, through multiple audio_output settings 
# blocks. Setting this block is optional, though the server will only attempt
# autodetection for one sound card.
#
# An example of an ALSA output:
#
#audio_output {
#   type        "alsa"
#   name        "My ALSA Device"
##  device      "hw:0,0"    # optional
##  mixer_type      "hardware"  # optional
##  mixer_device    "default"   # optional
##  mixer_control   "PCM"       # optional
##  mixer_index "0"     # optional
#}
#
# An example of an OSS output:
#
#audio_output {
#   type        "oss"
#   name        "My OSS Device"
##  device      "/dev/dsp"  # optional
##  mixer_type      "hardware"  # optional
##  mixer_device    "/dev/mixer"    # optional
##  mixer_control   "PCM"       # optional
#}
#
# An example of a shout output (for streaming to Icecast):
#
#audio_output {
#   type        "shout"
#   encoder     "vorbis"        # optional
#   name        "My Shout Stream"
#   host        "localhost"
#   port        "8000"
#   mount       "/mpd.ogg"
#   password    "hackme"
#   quality     "5.0"
#   bitrate     "128"
#   format      "44100:16:1"
##  protocol    "icecast2"      # optional
##  user        "source"        # optional
##  description "My Stream Description" # optional
##  url     "http://example.com"    # optional
##  genre       "jazz"          # optional
##  public      "no"            # optional
##  timeout     "2"         # optional
##  mixer_type      "software"      # optional
#}
#
# An example of a recorder output:
#
#audio_output {
#   type        "recorder"
#   name        "My recorder"
#   encoder     "vorbis"        # optional, vorbis or lame
#   path        "/var/lib/mpd/recorder/mpd.ogg"
##  quality     "5.0"           # do not define if bitrate is defined
#   bitrate     "128"           # do not define if quality is defined
#   format      "44100:16:1"
#}
#
# An example of a httpd output (built-in HTTP streaming server):
#
#audio_output {
#   type        "httpd"
#   name        "My HTTP Stream"
#   encoder     "vorbis"        # optional, vorbis or lame
#   port        "8000"
#   bind_to_address "0.0.0.0"       # optional, IPv4 or IPv6
##  quality     "5.0"           # do not define if bitrate is defined
#   bitrate     "128"           # do not define if quality is defined
#   format      "44100:16:1"
#   max_clients "0"         # optional 0=no limit
#}
#
# An example of a pulseaudio output (streaming to a remote pulseaudio server)
#
audio_output {
    type        "pulse"
    name        "My Pulse Output"
##  server      "remote_server"     # optional
##  sink        "remote_server_sink"    # optional
}
#
# An example of a winmm output (Windows multimedia API).
#
#audio_output {
#   type        "winmm"
#   name        "My WinMM output"
##  device      "Digital Audio (S/PDIF) (High Definition Audio Device)" # optional
#       or
##  device      "0"     # optional
##  mixer_type  "hardware"  # optional
#}
#
# An example of an openal output.
#
#audio_output {
#   type        "openal"
#   name        "My OpenAL output"
##  device      "Digital Audio (S/PDIF) (High Definition Audio Device)" # optional
#}
#
# An example of an sndio output.
#
#audio_output {
#   type        "sndio"
#   name        "sndio output"
#   mixer_type  "software"
#}
#
# An example of an OS X output:
#
#audio_output {
#   type        "osx"
#   name        "My OS X Device"
##  device      "Built-in Output"   # optional
##  channel_map      "-1,-1,0,1"    # optional
#}
#
## Example "pipe" output:
#
#audio_output {
#   type        "pipe"
#   name        "my pipe"
#   command     "aplay -f cd 2>/dev/null"
## Or if you're want to use AudioCompress
#   command     "AudioCompress -m | aplay -f cd 2>/dev/null"
## Or to send raw PCM stream through PCM:
#   command     "nc example.org 8765"
#   format      "44100:16:2"
#}
#
## An example of a null output (for no audio output):
#
#audio_output {
#   type        "null"
#   name        "My Null Output"
#   mixer_type      "none"          # optional
#}
#
###############################################################################


# Normalization automatic volume adjustments ##################################
#
# This setting specifies the type of ReplayGain to use. This setting can have
# the argument "off", "album", "track" or "auto". "auto" is a special mode that
# chooses between "track" and "album" depending on the current state of
# random playback. If random playback is enabled then "track" mode is used.
# See <http://www.replaygain.org> for more details about ReplayGain.
# This setting is off by default.
#
#replaygain         "album"
#
# This setting sets the pre-amp used for files that have ReplayGain tags. By
# default this setting is disabled.
#
#replaygain_preamp      "0"
#
# This setting sets the pre-amp used for files that do NOT have ReplayGain tags.
# By default this setting is disabled.
#
#replaygain_missing_preamp  "0"
#
# This setting enables or disables ReplayGain limiting.
# MPD calculates actual amplification based on the ReplayGain tags
# and replaygain_preamp / replaygain_missing_preamp setting.
# If replaygain_limit is enabled MPD will never amplify audio signal
# above its original level. If replaygain_limit is disabled such amplification
# might occur. By default this setting is enabled.
#
#replaygain_limit       "yes"
#
# This setting enables on-the-fly normalization volume adjustment. This will
# result in the volume of all playing audio to be adjusted so the output has 
# equal "loudness". This setting is disabled by default.
#
#volume_normalization       "no"
#
###############################################################################

# Character Encoding ##########################################################
#
# If file or directory names do not display correctly for your locale then you 
# may need to modify this setting.
#
#filesystem_charset     "UTF-8"
#
###############################################################################

Good luck!

  • Thanks! I'll check this tomorrow as well altough seeing the script and mpd work fine when the system is fully booted. So wouldn't MPD fail to work at all times if this was not yet solved? – Revam Jan 13 at 23:06
  • And still someone downvoted this post without an explanation! – kuzeyron Jan 17 at 15:12

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