Do I Need an Umbrella Today? Google Sheets and JavaScript to the Rescue!

gsheets-umbrellaOK, Google Sheets! Send me an email if I need an umbrella today.

Send an email using Google Sheets? Yes, that’s right! Sheets can do a lot more than add numbers and calculate your mortgage payments. In our last article, we learned how to consume JSON web data using Google Sheets and we built templates to display and sort weather forecast data. Today, we’ll build on what we covered last time and learn how to send email using Google Sheets based on the JSON data we retrieve.

Let’s get practical and build something useful while we’re at it. Have you ever found yourself outside somewhere and it starts to rain and you realize you forgot your umbrella? This has certainly happened to me! We have been experiencing drought conditions in Southern California for the last few years, and so I don’t always think about bringing an umbrella since rain is somewhat infrequent. (Thankfully, I’m hearing rain outside my window right now and we are receiving a lot more rain this year which is great!) Let’s use Google Sheets to improve our situational awareness by retrieving the weather forecast for the day and sending us an email before we leave in the morning if we should bring an umbrella. Let’s get started! Continue reading

Consuming JSON Web Data Using Google Sheets

article image
I’ve said it before, and I’ll say it again.  JSON has become the lingua franca for exchanging data on the web, and we (as developers) need to know how to process JSON data received from RESTful web services so we can be positioned for the present and for the future.

My article on Consuming Node.js Microservices Created with stdlib provided a high-level tour covering several methods of parsing and processing JSON data. Last time, we focused on how to consume JSON data using curl and jq. Today, we’re zooming in and learning more about consuming Web API JSON data using Google Sheets. Once again, we’ll be consuming data from a microservice created with the excellent stdlib platform. Our learning, however, will be universally applicable for consuming Web API JSON data from any http endpoint. I am very impressed with the power and versatility of the Google Sheets platform for consuming JSON data (among many other things).  Let’s get started and experience it firsthand! Continue reading

Consuming Web API JSON Data Using curl and jq

curl-jq

Hey everyone!  I decided to put a few extra batteries in the background color of the article image above. 🙂  I’m actually pretty charged up about our topic today, particularly about jq, which is a lightweight and flexible command-line JSON processor with “batteries included”.

JSON has become the lingua franca for exchanging data on the web, and we (as developers) need to know how to process JSON data so we can be positioned for the present and for the future. We recently learned about Consuming Node.js Microservices Created with Stdlib which provided a high-level tour covering several methods for parsing and processing JSON data. Today, we’re zooming in and learning more about consuming Web API JSON data from bash using curl and jq. Once again, we’ll be consuming data from a microservice created with the excellent stdlib platform. Our learning, however, will be universally applicable for consuming Web API JSON data from any http endpoint. Most importantly, we’re going to have fun in the process! 🙂 Continue reading

Creating a Raspberry Pi Pandora Player with Remote Web Control

pi pandora
In our last article, we learned how to control a Raspberry Pi from a mobile device and, as a bonus, we created a menu to make it even easier to issue commands and control our Pi. We’re back today to put that remote menu to good use because we’re building an amazing Pandora music player we can connect to a stereo in our living room, for example, without a monitor, keyboard, or mouse. Our system will include a web interface served through Node.js so we can control our Pandora player remotely from a mobile phone—all from the comfort of our couch. 🙂 Follow along with me and let’s make this happen!

Article Contents

Complete Prerequisites

Prepare your Raspberry Pi

If you have not already followed my Beginner’s Guide to Installing Node.js on a Raspberry Pi, I recommend that you take a look at that now. In this guide, I equip you with the knowledge needed to build an awesome Raspberry Pi system that can also run in a headless mode. We’re able to avoid a dedicated monitor, keyboard, and mouse, and this is exactly what we need to maximize the awesomeness of our Pandora player.

At the very least, make sure you follow the steps to install Node.js because Node.js will be powering the built-in Pandora web server we’ll be accessing from our mobile devices.

Create Pandora account

If you do not already have a Pandora account, go ahead and visit Pandora.com and create one now. Pandora is “free personalized radio that plays the music you love”. What’s not to love about that? 🙂

While you are logged into Pandora, go ahead and create a couple of stations. Our remote web interface will ultimately need stations in order to to play music for us.

Install additional packages

We’ll need a couple of additional packages to utilize our Pandora player. First, let’s install pianobar, an amazing console-based pandora.com player underpinning our entire project:

$ sudo apt install pianobar

Next, we’ll install screen, a terminal-based window manager that our software will use behind the scenes in conjunction with pianobar:

$ sudo apt install screen

Install Patiobar

As a next step, we’ll install and configure Patiobar, a web frontend for pianobar created by Kyle Johnson. I was gearing up to create a web interface to pianobar and came across Kyle’s project. He has done an excellent job, and we’ll be leveraging his work to create this fantastic music system.

Go ahead and ensure your terminal session is in your home directory:

$ cd ~

Also, these very next steps require Node.js so make sure you have that installed.

Ok, let’s install Patiobar.  Execute this next set of commands one by one from the terminal:

$ git clone https://github.com/kylejohnson/Patiobar.git
$ cd Patiobar
$ bash install.sh

Excellent! We just made some serious progress and installed the foundational elements needed for our Patiobar web server.

Configure pianobar so it’s ready to be used by Patiobar

Our Patiobar web frontend ultimately uses pianobar behind the scenes to serve up music from Pandora so we need to make sure pianobar is configured and in working order first.

Launch the pianobar configuration file for editing using the Leafpad text editor:

$ leafpad ~/.config/pianobar/config &

The contents will look something like this:

user = you@user.com
user = user@example.com
password = password
#autostart_station = 123456
audio_quality = high
event_command = /home/pi/Patiobar/eventcmd.sh
fifo = /home/pi/Patiobar/ctl
tls_fingerprint = FC2E6AF49FC63AEDAD1078DC22D1185B809E7534

Substitute the user parameter with your Pandora user account email, and substitute the password with your Pandora password, and save your changes.

Great work! We’re making excellent progress and we’re ready to launch pianobar by itself to confirm it works. Connect a set of earbuds or speakers to the audio output jack of your Raspberry Pi. Get ready to hear some music!

Issue the following command to launch pianobar:

$ pianobar

At this point, pianobar should log into Pandora and prompt you to select a station for listening. Go ahead and select the default station that you would like to start each time the Raspberry Pi music player starts. You will be able to change this station from the web interface that is provided, but we need a starting station to bootstrap our player each time it starts. The pianobar station selection dialog will look something like this:

[?] Select station: 2
|> Station "David Nevue (Holiday) Radio" (3749270268933429865)

After selecting a station, hit Ctrl+C to quit. You will need the long station number listed in parentheses, 3749270268933429865, as shown in our example above, for the next step.

Edit the pianobar configuration file one more time:

$ leafpad ~/.config/pianobar/config &

Replace the existing autostart_station line with the long station number you obtained above. Be sure to remove the “#” from the beginning of the line so pianobar can read the autostart_station configuration information.

autostart_station = 3749270268933429865

Save your changes and launch pianobar again.

$ pianobar

This time, pianobar should jump right in and begin playing your default station without intervention required by you. Assuming this is the case, you are ready to finish the installation so we can use pianobar with the awesome Patiobar web frontend powered by Node.js.

Create Patiobar start and stop scripts

Okay, let’s create a couple of scripts to make it easy to start and stop Patiobar.

Create bin directory to make our menu command accessible from any directory

First, we will create a directory so our scripts will be accessible from any directory on our system without the need to provide a full path name to our script.

From the terminal, return to your home directory if you are not already there.

$ cd ~

Next, create a directory called bin:

$ mkdir bin

We will need to edit our .bashrc file to include this bin directory in our PATH variable. This will ensure that any scripts located in our newly created bin directory can be invoked from any directory on our system without needing to include the full path to the script. Let’s first launch a text editor so we can edit the .bashrc file:

$ leafpad .bashrc &

Add the following line to the bottom of this file:

export PATH="$HOME/bin:$PATH"

Save your changes and close the leafpad editor.

To ensure our changes to the .bashrc file are processed right away, invoke this command:

$ source .bashrc

Perfect! We are now positioned to create our Patiobar start and stop scripts.

Create pbstart (Patiobar start) command

We’ll use leafpad once again to create our new command. We’ll call our command pbstart (Patiobar start):

$ leafpad ~/bin/pbstart &

Add the following contents and save the file.

#!/bin/bash

cd /home/pi/Patiobar

# Kill any old Patiobar processes running
pbstop 1> /dev/null

screen -S pianobar -d -m bash -c 'pianobar'

# The "patiobar" in the end is not needed and is used as an identifier so we can kill it when stopping.
# Otherwise, we might kill other "node index.js" processes.
node index.js patiobar > /dev/null 2>&1 &

echo "Go to http://$(hostname):3000/ to launch the Web interface."

Create pbstop (Patiobar stop) command

Using leafpad once again, create a second command called pbstop (Patiobar stop):

$ leafpad ~/bin/pbstop &

Add the following contents and save the file.

#!/bin/bash

echo Closing out Pandora processes...
pkill -xf "SCREEN -S pianobar -d -m bash -c pianobar"
pkill -xf "node index.js patiobar"
echo done

Set user execute bit on the pbstart/stop scripts

Finally, set the user execute bit on both files so the pi user has permission to run the scripts:

$ chmod u+x ~/bin/pbstart
$ chmod u+x ~/bin/pbstop

Launch Patiobar and start listening to music!

Okay, here’s the moment of truth. Let’s try out our pbstart command and see if we can start up Patiobar. Remember that we can invoke this command from any directory on our system since it is part of our PATH. Here we go!

$ pbstart

Patiobar should start up pianobar, and you should both hear music and be able to navigate to the Patiobar web interface running on port 3000. For example, my Raspberry Pi host name is called “pandora” so I would navigate to http://pandora:3000. It’s December and I’m listening to Christmas music so this is what I see when launching the web interface from my mobile phone:
David Nevue
The interface is excellent and we can change stations using the “hamburger” menu in the top right, and pause, skip songs, etc. There’s even album art as you can see!

When you are done listening, stop the Patiobar player so you do not consume all your Pandora minutes:

$ pbstop

Install SSH client on mobile phone to control Pianobar start/stop remotely (optional)

We learned how to control a Raspberry Pi from a mobile device] in our last article and I encourage you to read that article to learn how to install an SSH client on your mobile device so you can invoke terminal commands from your phone. It’s pretty amazing and useful to not be tethered to a laptop or desktop and still log in and interact with your Pi!

After the mobile SSH client is installed you will be able to invoke pbstart from your mobile device to start Patiobar, stop Pianobar with pbstop, and safety shut down your Pi using the following command:

$ sudo poweroff

Utilizing a mobile SSH client is a much better option for shutting down your headless Pi gracefully rather than yanking the power cord out and risking potential corruption of your microSD card.

Add menu for remote control from mobile phone (optional)

To make it even easier to invoke commands, our last article on controlling a Raspberry Pi from a mobile device also included a bonus section on creating a menu system. You can follow the steps in that article to create a menu system that looks something like this for our current Pandora player project:
rmenu pandora
After following the steps in the controlling a Raspberry Pi from a mobile device article, you can create a file called menu2.sh in the same directory as the rmenu command like this:

$ leafpad ~/bin/menu2.sh &

…and add the following contents:

show_menu () {
    # We show the host name right in the menu title so we know which Pi we are connected to
    OPTION=$(whiptail --title "Menu (Host:$(hostname))" --menu "Choose your option:" 12 36 5 \
    "1" "Uptime" \
    "2" "Start Pandora" \
    "3" "Stop Pandora" \
    "4" "Reboot Pi" \
    "5" "Shut down Pi"  3>&1 1>&2 2>&3)
 
    BUTTON=$?

    # Check if user pressed cancel or escape
    if [[ ($BUTTON -eq 1) || ($BUTTON -eq 255) ]]; then
        exit 1
    fi

    if [ $BUTTON -eq 0 ]; then
        case $OPTION in
        1)
            MSG="$(uptime)"
            whiptail --title "Uptime info" --msgbox "$MSG" 8 36
            show_menu
            ;;
        2)
            pbstart
            msg="Go to http://$(hostname):3000/ to launch the Web interface."
            whiptail --title "Note" --msgbox "$msg" 8 36
            show_menu
            ;;
        3)
            pbstop
            sleep 2
            show_menu
            ;;
        4)
            confirmAnswer "Are you sure you want to reboot the Pi?"
            if [ $? = 0 ]; then
                echo Rebooting...
                sudo reboot
            else
                show_menu
            fi
            ;;
        5)
            confirmAnswer "Are you sure you want to shut down the Pi?"
            if [ $? = 0 ]; then
                echo Shutting down...
                sudo poweroff
            else
                show_menu
            fi
            ;;
        esac
    fi
}

This new menu (menu2.sh) can then be invoked from rmenu as follows:

$ rmenu -m 2

As a final step (as outlined in the previous article), you can add this rmenu -m 2 command to ~/.profile so the menu starts automatically when you SSH into the Pi from your mobile device.

Launch Patiobar automatically on startup (optional)

If you have a dedicated microSD card for your Pandora player, you might want to start Patiobar automatically each time you power on your Raspberry Pi. This makes it easier to, for example, power on a Pi connected to speakers in your living room without the need to SSH into the Pi upon boot to issue a pbstart command. The downside is that you might be playing music and burning Pandora time when you don’t even realize music is playing. 🙂

To start Patiobar automatically every time you boot, use sudo to edit the following file since this file requires root privileges:

$ sudo leafpad /etc/rc.local &

Add the following line just above the last line in the file with the contents of exit 0:

sleep 15 && sudo -iu pi /home/pi/bin/pbstart

The /etc/rc.local script runs every time the Pi boots up. We sleep for 15 seconds before invoking the pbstart command under the aegis of the pi user. The 15 second “nap” 🙂 gives time for the network to stabilize before the pbstart script connects to Pandora.com and begins to stream music.

Save the file and close leafpad. Finally, reboot your Pi.

$ sudo reboot

After the Pi finishes its boot cycle (and another 15 seconds after that), you should start hearing music streaming from Pandora automatically!

Troubleshooting in the future (if music does not play)

Sometime down the road, you may be faced with a situation where music does not play.  This could very well be caused by the fact that the “TLS fingerprint” associated with the Pandora website has expired. When Pandora updates their SSL certificates, a new TLS fingerprint is needed. Keep this in mind in the future when Patiobar stops working and you can’t figure out why. Revisit this section and update the TLS fingerprint as we will describe now.

First, run pianobar as a standalone program separate from Patiobar to verify this is the issue:

$ pianobar

If you do not hear music, but instead see an error message indicating a “TLS fingerprint mismatch”, proceed with the next steps to resolve this issue.

We first need to copy over a handy script included with the pianobar distribution to our current directory so we can retrieve the latest TLS fingerprint:

$ cp /usr/share/doc/pianobar/contrib/tls_fingerprint.sh .

Next, set the user execute bit to make sure we can run the script:

$ chmod u+x tls_fingerprint.sh

Go ahead and invoke this script to retrieve the TLS fingerprint:

$ bash tls_fingerprint.sh

You should see something like this: FC2E6AF49FC63AEDAD1078DC22D1185B809E7534

Next, edit the pianobar configuration file:

$ leafpad ~/.config/pianobar/config &

Replace the existing tls_fingerprint configuration parameter with the new TLS fingerprint obtained:

tls_fingerprint = FC2E6AF49FC63AEDAD1078DC22D1185B809E7534

Run pianobar to verify that it now works before issuing a pbstart to restart Patiobar:

$ pianobar

You should hear music playing and be back in business!

Conclusion

There you have it! We created an amazing Pandora player that can be controlled remotely from a mobile device. We can control our Pandora listening experience through a web interface. As a bonus, we can also start and stop our Pandora player through an SSH interface on a mobile device with a handy menu as well. We are ready to enjoy music with family and friends—and we learned some cool technology tricks in the process!

Follow @thisDaveJ (Dave Johnson) on Twitter to stay up to date with the latest tutorials and tech articles.

Additional articles

Controlling a Raspberry Pi from a Mobile Device with Bonus Menu Too
Beginner’s Guide to Installing Node.js on a Raspberry Pi
Connecting a Raspberry Pi Using an Ethernet Crossover Cable and Internet Connection Sharing
Upgrading to more recent versions of Node.js on the Raspberry Pi

Controlling a Raspberry Pi from a Mobile Device with Bonus Menu Too

rmain main

In my Beginner’s Guide to Installing Node.js on a Raspberry Pi, I equipped you with the knowledge needed to build an awesome Raspberry Pi system that could also run in a headless mode. We’re able to avoid a dedicated monitor, keyboard, and mouse, and this opens a whole new world of possibilities!

This brings us to today’s scenario: you’ve deployed your headless Raspberry Pi in the living room and connected it to your speaker system, soaking in the full stereo sound of your favorite music using pianobar, the console-based Pandora player. It’s eventually time for bed and you’re tired. Should you yank the power cord on your Raspberry Pi and call it a night? Probably not – you might risk corrupting the microSD card. Should you walk upstairs and re-open your laptop so you can SSH into the Pi and safety shut it down? That’s a lot of work! Wouldn’t it be fantastic if you could connect to your Pi from the mobile phone sitting next to you and issue that shutdown -h now command? Controlling your Pi from a mobile device could be very useful in other contexts too beyond listening to music such as IoT applications, computer vision systems, Magic Mirrors, etc.

In this guide, I will teach you how to control your Raspberry Pi from a mobile device. As a bonus, we will create a menu application to make it easier to issue commands since typing complicated command-line syntax on a small screen can prove to be challenging! Let’s jump right in! Continue reading

Consuming Node.js Microservices Created with Stdlib

stdlib-consumers
In our last article, we learned how to create Node.js microservices using Polybit’s stdlib platform. We created a fabulous (IMHO 🙂 ) GPS service that enabled us to retrieve the name of a city based on its GPS coordinates. Today, we’re going to learn how to consume data returned from this stdlib GPS microservice using several methods. While the information presented here is specific to consuming Polybit stdlib microservices, many aspects of this article will be generally applicable for consuming Web API JSON data from any http endpoint. Strap on your seatbelts as we embark on a whirlwind tour to learn about consuming JSON data from a variety of contexts…and I’m talking about some serious variety! Continue reading

Node.js: Playing Sounds to Provide Notifications

playing sounds

In a previous tutorial, we learned how to send email notifications Using Nodemailer and Gmail. In today’s session, we will learn how to play sounds using Node.js. As a bonus, we will learn how to continue to play a sound until our notification has been acknowledged by pressing a key on the keyboard. How does that sound? 🙂 Enough bad puns! 🙂 Let’s get started! Continue reading

Creating Node.js Microservices with Ease Using Stdlib

stdlibMicroservices and serverless architectures are all the rage in the software industry. After working with Polybit’s amazing stdlib platform, I am clearly seeing the value of this promising technology! Today, I will introduce you to stdlib. I encourage you to work alongside me as we leverage stdlib to build a microservice that we can consume in a variety of contexts. Let’s get started with this fabulous technology! Continue reading

Build an Amazing HTML Editor Using Visual Studio Code

vscode html
Today we’re going to build an amazing HTML editor using Visual Studio Code (VS Code), a powerful, versatile cross-platform code editor that provides a lot of capabilities. Let’s get this out of the way up front: I’m a raving VS Code fan! In a previous post, I showed you how to Build an Amazing Markdown Editor, and now we’re going to learn how to create a fabulous HTML editor as well. Let’s get started! Continue reading

Upgrading to more recent versions of Node.js on the Raspberry Pi

upgrading nodejs

I’ve received questions from readers of my Beginner’s Guide to Installing Node.js on a Raspberry Pi wanting to know how to upgrade to more recent versions of Node.js on the Raspberry Pi.  The steps are quite easy and can be adapted to other Debian variants as well including Ubuntu.  I’m assuming you followed the steps in my Beginners’ Guide, especially under the “Install Node.js” section where we update the Raspbian/Debian package repository to include the Node.js binaries provided by NodeSource.  Let’s get started! Continue reading