OctoPrint – the snappy web interface for your 3D printer

References

• OctoPrint home page
• OctoPrint Community Forum
• DockerHub octoprint/octoprint
• GitHub OctoPrint/octoprint-docker

Device mappings

When you select "OctoPrint" in the IOTstack menu, the service definition in your docker-compose.yml, contains the following under the devices: heading:

devices:
  - /dev/ttyAMA0:/dev/ttyACM0
# - /dev/video0:/dev/video0

the /dev/ttyAMA0:/dev/ttyACM0 mapping

The /dev/ttyAMA0:/dev/ttyACM0 mapping should be read as saying "the physical Raspberry Pi device /dev/ttyAMA0 is mapped to the logical OctoPrint container device /dev/ttyACM0".

The /dev/ttyAMA0 device is used as a default because it is always present on Raspbian. If you bring up your container like that, the mapping will succeed and the container is unlikely to go into a restart loop.

However, the OctoPrint container is unlikely to be able to connect to your 3D printer via /dev/ttyAMA0 for the very simple reason that that is not how 3D printers usually appear on the Raspberry Pi. You need to work out how your printer presents itself and change the device mapping accordingly.

option 1 - /dev/ttyUSBn

Using "ttyUSBn" will "work" but, because of the inherent variability in the name, this approach is not recommended.

The "n" in the "ttyUSBn" can vary depending on which USB devices are attached to your Raspberry Pi and the order in which they are attached. The "n" may also change as you add and remove devices.

If the OctoPrint container is up when the device number changes, the container will crash, and it will either go into a restart loop if you try to bring it up when the expected device is not "there", or will try to communicate with a device that isn't your 3D printer.

option 2 - /dev/serial/by-id/xxxxxxxx

The "xxxxxxxx" is (usually) unique to your 3D printer. To find it, connect your printer to your Raspberry Pi, then run the command:

$ ls -1 /dev/serial/by-id

You will get an answer like this:

usb-Silicon_Labs_CP2102N_USB_to_UART_Bridge_Controller_3b14eaa48a154d5e87032d59459d5206-if00-port0

Note:

• If you have multiple serial devices attached, you will get multiple lines in the output. It is up to you to sort out which one belongs to your 3D printer, possibly by disconnecting and re-attaching the printer and observing how the list changes.
• The uniqueness of device IDs is under the control of the device manufacturer. Each manufacturer should ensure their devices are unique but some manufacturers are more diligent than others.

Assuming the above example output was the answer, edit docker-compose.yml to look like this:

devices:
  - /dev/serial/by-id/usb-Silicon_Labs_CP2102N_USB_to_UART_Bridge_Controller_3b14eaa48a154d5e87032d59459d5206-if00-port0:/dev/ttyACM0

Notes:

• device by-id names follow the device. In other words, if you have two or more Raspberry Pis and a collection of serial devices (3D printers, Zigbee adapters, UARTs, and so on), a 3D printer will always get the same by-id name, irrespective of which Raspberry Pi it is attached to.
• device by-id names do not persist if the physical device is disconnected. If you switch off your 3D printer or disconnect the USB cable while the OctoPrint container is running, the container will crash.

option 3 - /dev/humanReadableName

Suppose your 3D printer is a MasterDisaster5000Pro, and that you would like to be able to set up the device to use a human-readable name like:

/dev/MasterDisaster5000Pro

Start by disconnecting your 3D printer from your Raspberry Pi. Next, run this command:

$ tail -f /var/log/messages

Connect your 3D printer and observe the log output. You are interested in messages that look like this:

mmm dd hh:mm:ss mypi kernel: [423839.626522] cp210x 1-1.1.3:1.0: device disconnected
mmm dd hh:mm:ss mypi kernel: [431265.973308] usb 1-1.1.3: new full-speed USB device number 10 using dwc_otg
mmm dd hh:mm:ss mypi kernel: [431266.109418] usb 1-1.1.3: New USB device found, idVendor=dead, idProduct=beef, bcdDevice= 1.00
mmm dd hh:mm:ss mypi kernel: [431266.109439] usb 1-1.1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
mmm dd hh:mm:ss mypi kernel: [431266.109456] usb 1-1.1.3: Product: CP2102N USB to UART Bridge Controller
mmm dd hh:mm:ss mypi kernel: [431266.109471] usb 1-1.1.3: Manufacturer: Silicon Labs
mmm dd hh:mm:ss mypi kernel: [431266.109486] usb 1-1.1.3: SerialNumber: cafe80facefeed
mmm dd hh:mm:ss mypi kernel: [431266.110657] cp210x 1-1.1.3:1.0: cp210x converter detected
mmm dd hh:mm:ss mypi kernel: [431266.119225] usb 1-1.1.3: cp210x converter now attached to ttyUSB0

and, in particular, these two lines:

… New USB device found, idVendor=dead, idProduct=beef, bcdDevice= 1.00
… SerialNumber: cafe80facefeed

Terminate the tail command by pressing Control+C.

Use this line as a template:

SUBSYSTEM=="tty", ATTRS{idVendor}=="«idVendor»", ATTRS{idProduct}=="«idProduct»", ATTRS{serial}=="«SerialNumber»", SYMLINK+="«sensibleName»"

Replace the «delimited» values with those you see in the log output. For example, given the above log output, and the desire to associate your 3D printer with the human-readable name of "MasterDisaster5000Pro", the result would be:

SUBSYSTEM=="tty", ATTRS{idVendor}=="dead", ATTRS{idProduct}=="beef", ATTRS{serial}=="cafe80facefeed", SYMLINK+="MasterDisaster5000Pro"

Next, ensure the required file exists by executing the following command:

$ sudo touch /etc/udev/rules.d/99-usb-serial.rules

If the file does not exist already, the touch command creates an empty file, owned by root, with mode 644 (rw-r--r--) permissions (all of which are correct).

Use sudo and your favourite text editor to edit /etc/udev/rules.d/99-usb-serial.rules and insert the "SUBSYSTEM==" line you prepared earlier into that file, then save the file.

Rules files are read on demand so there is no start or reload command to execute.

Check your work by disconnecting, then re-connecting your 3D printer, and then run:

$ ls /dev

You should expect to see the human-readable name you chose in the list of devices. You can then edit docker-compose.yml to use the name in the device mapping.

devices:
  - /dev/MasterDisaster5000Pro:/dev/ttyACM0

Notes:

• device names follow the device. In other words, if you have two or more Raspberry Pis and a collection of serial devices (3D printers, Zigbee adapters, UARTs, and so on), you can build a single 99-usb-serial.rules file that you install on all of your Raspberry Pis. Then, you can attach a named device to any of your Raspberry Pis and it will always get the same name.
• device names do not persist if the physical device is disconnected. If you switch off your 3D printer or disconnect the USB cable while the OctoPrint container is running, the container will crash.

the /dev/video0:/dev/video0 mapping

The /dev/video0 device is assumed to be an official Raspberry Pi camera attached via ribbon cable.

See the Webcams topic of the Octoprint Community Forum for help configuring other kinds of cameras.

The OctoPrint docker image includes an MJPG streamer. You do not need to run another container with a streamer unless you want to.

To activate a Raspberry Pi camera attached via ribbon cable:

1. Follow the instructions at raspberrypi.org to connect and test the camera. There are guides on YouTube (example) if you need help working out how to insert the ribbon cable.
2. Confirm the presence of /dev/video0.

3. Edit docker-compose.yml and uncomment all of the commented-out lines in the following:

   devices:
   # - /dev/video0:/dev/video0
   environment:
   # - ENABLE_MJPG_STREAMER=true
   # - MJPG_STREAMER_INPUT=-r 640x480 -f 10 -y
   # - CAMERA_DEV=/dev/video0
   

   Note:

   • The device path on the right hand side of the CAMERA_DEV environment variable corresponds with the right hand side (ie after the colon) of the device mapping. There should be no reason to change either.

The three environment variables are required:

environment:
  - ENABLE_MJPG_STREAMER=true
  - MJPG_STREAMER_INPUT=-r 640x480 -f 10 -y
  - CAMERA_DEV=/dev/video0

The "640x480" MJPG_STREAMER_INPUT settings will probably result in your camera feed being "letterboxed" but they will get you started. A full list of options is at mjpg-streamer-configuration-options.

The typical specs for a baseline Raspberry Pi camera are:

• 1080p 720p 5Mp Webcam
• Max resolution: 2592x1944
• Max frame rate: VGA 90fps, 1080p 30fps
• CODEC: MJPG H.264 AVC

For that type of camera, the following is probably more appropriate:

  - MJPG_STREAMER_INPUT=-r 1152x648 -f 10

The resolution of 1152x648 is 60% of 1080p 1920x1080 and does not cause letterboxing. The resolution and rate of 10 frames per second won't over-tax your communications links, and the camera is MJPEG-capable so it does not need the -y option.

Practical usage

starting the OctoPrint container

To start a print session:

1. Turn the 3D printer on.

2. Bring up the container:

   $ cd ~/IOTstack
   $ docker-compose up -d octoprint
   

If you try to start the OctoPrint container before your 3D printer has been switched on and the USB interface has registered with the Raspberry Pi, the container will go into a restart loop.

first run – the Setup Wizard

Use a browser to point to port 9980 on your Raspberry Pi. For example:

http://raspberrypi.local:9980

This will launch the "Setup Wizard".

1. Click the "Next" button until you reach the "Access Control" screen:

   • Define a Username and Password, and keep a record of your decisions.
   • Click "Create Account".
   • Ignore the alarming popup alert by clicking "Ignore". This alert is a result of OctoPrint running in a Docker container.
   • Click "Next".

2. At the "Online Connectivity Check" screen:

   • Click "Disable Connectivity Check".
   • Click "Next".

3. At the "Configure Anonymous Usage Tracking" and "Configure plugin blacklist processing" screens:

   • Make a decision about whether you want the feature enabled or disabled and click the appropriate button.
   • Click "Next".

4. At the "Set up your printer profile" screen:

   • It is probably a good idea to visit the tabs and set values appropriate to your printer (build volume, at least).
   • Click "Next".

5. At the "Server Commands" screen:

   • Enter the following in the "Restart OctoPrint" field:

     s6-svc -r /var/run/s6/services/octoprint
     

   • Click "Next".

6. At the "Webcam & Timelapse Recordings" screen, and assuming you are configuring a PiCamera:

   • Enter the following in the "Stream URL" field:

     /webcam/?action=stream
     

     Click the "Test" button to confirm that the camera is working, then click "Close".

   • Enter the following in the "Snapshot URL" field:

     http://localhost:8080/?action=snapshot
     

     Click the "Test" button to confirm that the camera is working, then click "Close".

   • Enter the following in the "Path to FFMPEG" field:

     /usr/bin/ffmpeg
     

     The expected result is the message "The path is valid".

   • Click "Next".

7. Click "Finish" then click the button to reload the user interface.

after the first run

Use a browser to point to port 9980 on your Raspberry Pi. For example:

http://raspberrypi.local:9980

Supply your user credentials and login.

popup messages

OctoPrint will display numerous messages in popup windows. These generally fall into two categories:

• Messages that refer to updates; and
• Messages that refer to other events.

In general, you can ignore messages about updates. You will get all updates automatically the next time the octoprint-docker container is rebuilt and pushed to DockerHub.

You can, if you wish, allow an update to proceed. It might be appropriate to do that if you want to test an update. Just be aware that:

1. Updates are ephemeral and will disappear the next time the Octoprint container is created.
2. Updates can change the structure of the persistent storage area in a way which can't be undone, and which may prevent the Octoprint container from starting the next time it is created. In other words, if you want to trial an update, take a backup of OctoPrint's persistent storage area first.

restarting the OctoPrint container

You can restart the OctoPrint service in two ways:

• via the Raspberry Pi command line; or
• via the OctoPrint user interface.

Whichever method you choose will result in a refresh of the OctoPrint user interface and you will need to follow the prompts to reload your browser page.

restarting via the command line

Run the following commands:

$ cd ~/IOTstack
$ docker-compose restart octoprint

restarting via OctoPrint user interface

From the "System" icon in the OctoPrint toolbar (looks like a power button symbol):

1. Choose "Restart OctoPrint".

Note:

• If you do not see the "System" icon in the toolbar, fix it line this:

  1. Click the "Settings" icon (looks like a wrench) in the OctoPrint toolbar.
  2. Choose "Server".

  3. Enter the following into the "Restart OctoPrint" field:

     s6-svc -r /var/run/s6/services/octoprint
     

  4. Click "Save".

stopping the OctoPrint container

Unless you intend to leave your printer switched on 24 hours a day, you will also need to be careful when you switch off the printer:

1. Terminate the container:

   $ cd ~/IOTstack
   $ docker-compose stop octoprint
   $ docker-compose rm -f octoprint
   

2. Turn the 3D printer off.

If you turn the printer off without terminating the container, you will crash the container.

Video feed (built-in camera interface)

You can view the video feed independently of the OctoPrint web interface like this:

http://raspberrypi.local:9980/webcam/?action=stream

Silencing the security warning

OctoPrint assumes it is running "natively" rather than in a container. From a data-communications perspective, OctoPrint (the process running inside the OctoPrint container) sees itself as running on a computer attached to the internal Docker network. When you connect to OctoPrint's web interface from a client device attached to an external network, OctoPrint sees that your source IP address is not on the internal Docker network and it issues a security warning.

To silence the warning:

1. Terminate the container if it is running:

   $ cd ~/IOTstack
   $ docker-compose stop octoprint
   $ docker-compose rm -f octoprint
   

2. use sudo and your favourite text editor to open the following file:

   ~/IOTstack/volumes/octoprint/octoprint/config.yaml
   

3. Implement the following pattern:

   server:
     …
     ipCheck:
       enabled: true
       trustedSubnets:
       - 203.0.132.0/24
   

   Notes:

   • The server:, ipCheck: and enabled: directives may already be in place but the trustedSubnets: directive may not be. Add it, and then add your local subnet(s) where you see the "192.168.1.0/24" example.
   • Remember to use spaces in YAML files. Do not use tabs.

4. Save the file.

5. Bring up the container:

   $ cd ~/IOTstack
   $ docker-compose up -d octoprint
   

Routine container maintenance

You can check for updates like this:

$ cd ~/IOTstack
$ docker-compose pull octoprint
$ docker-compose up -d octoprint
$ docker system prune

If you forget your username and password

You can view a list of usernames like this:

$ docker exec octoprint octoprint --basedir /octoprint/octoprint user list

To reset a user's password:

1. Use the following line as a template and replace «username» and «password» with appropriate values:

   $ docker exec octoprint octoprint --basedir /octoprint/octoprint user password --password «password» «username»
   

2. Execute the edited command. For example, to set the password for user "me" to "verySecure":

   $ docker exec octoprint octoprint --basedir /octoprint/octoprint user password --password verySecure me
   

3. Restart OctoPrint:

   $ cd ~/IOTstack
   $ docker-compose restart octoprint
   

Note:

• OctoPrint supports more than one username. To explore the further:

  $ docker exec octoprint octoprint --basedir /octoprint/octoprint user --help
  

If all else fails…

If the OctoPrint container seems to be misbehaving, you can get a "clean slate" by:

$ cd ~/IOTstack
$ docker-compose stop octoprint
$ docker-compose rm -f octoprint
$ sudo rm -rf ./volumes/octoprint
$ docker-compose up -d octoprint

The OctoPrint container is well-behaved and will re-initialise its persistent storage area correctly. OctoPrint will adopt "first run" behaviour and display the Setup Wizard.