Use uStreamer launcher. (#1252)

Resolves #1249

Now that the [uStreamer launcher
script](tiny-pilot/ansible-role-ustreamer#89)
dynamically determines the correct uStreamer command-line options, we
don't need to run our Ansible playbook to apply video settings.

This PR removes the use of the `update-video-settings` script and uses
the [backported `video-service`
module](#1251) to apply the
current video settings found in `/home/tinypilot/settings.yml`.

### Notes

1. This PR is based on @mtlynch's [uStreamer launcher proof of concept
PR](tiny-pilot/tinypilot-pro#701) and resolves
the following missing parts:
> - Add JS logic to make sure that uStreamer/Janus is up and serving
again before reloading the page
> - If we reload too early, we'll get an HTTP 502 error because
uStreamer isn't listening for inbound connections yet. I've seen this in
MJPEG and not in H264 mode, but I'm not sure whether it could happen in
H264 as well.
    
To ensure that the MJPEG stream is available, I
[poll](https://github.com/tiny-pilot/tinypilot/blob/54b6abfa03b2ae2e055261659b0e4f160af60fba/app/templates/custom-elements/video-settings-dialog.html#L450-L456)
the [`/stream` endpoint until it gives us a `200
OK`](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/static/js/controllers.js#L314-L326).
   
As for the H264 stream, our connection to Janus does disconnect once the
new video settings are applied (because [Janus is
restarted](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/video_service.py#L19)),
but once we [reload the
page](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/templates/custom-elements/video-settings-dialog.html#L464)
Janus is already back online. I also didn't manage to get Janus to
return an error after the page has been reloaded. I do think it's still
technically possible to get an error in H264 mode, but rather unlikely.
If we did want to eliminate any possibility of the error, we would have
to implement "automatic reconnection" logic in `webrtc-video.js`. Some
investigation reveals that we just need to [recreate the `Janus`
instance](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/static/js/webrtc-video.js#L44-L56)
when the [client is
disconnected](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/static/js/webrtc-video.js#L48-L55).
The `janus.js` library does have a [`recover`
method](https://github.com/meetecho/janus-gateway/blob/v0.9.2/html/janus.js#L531)
to reconnect/reclaim to an existing session, but this doesn't work if
the Janus service has been restarted because Janus forgets all sessions
when restarted.

    > - Find a way to make video settings work in dev mode
> - It used to work through the mock script, but now we're no longer
calling an external script, so we need another solution.
> - Maybe just check the debug mode [in
video_settings.apply](https://github.com/tiny-pilot/tinypilot-pro/blob/1a8bf29292b0075e362711148645fa42a981bea8/app/video_settings.py#L18)?

This is no longer an issue because applying video settings now just
means restarting uStreamer/Janus, and those video services are restarted
in a best effort manner (i.e., [we ignore any errors that might
occur](https://github.com/tiny-pilot/tinypilot/blob/378f6919f1c4c347517ac7a39e8a2b8c8f6c6899/app/video_service.py#L34))
and only log any potential errors. So in dev mode, the command would
silently fail and the error is logged as:

    ```
2023-01-12 16:27:15.361 video_service ERROR Failed to restart ustreamer:
Command '['sudo', '/usr/sbin/service', 'ustreamer', 'restart']' returned
non-zero exit status 1.
2023-01-12 16:29:16.778 video_service ERROR Failed to restart janus:
Command '['sudo', '/usr/sbin/service', 'janus', 'restart']' returned
non-zero exit status 1.
    ```

> - Dump uStreamer settings in log collection script instead of [systemd
settings](https://github.com/tiny-pilot/tinypilot/blob/1dff200fa1915f3a37bccf7d09b67a4387892b45/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs#L140)
> - Now the systemd settings are going to be uninteresting. In
collect-debug-logs, we should be dumping the contents of files in
`/opt/ustreamer-launcher/configs.d/`


[Done](https://github.com/tiny-pilot/tinypilot/blob/92f2dac143824abdee3dd6c05419f94075b654e3/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs#L140).
As @mtlynch
[mentioned](#1252 (comment)),
we just want to log the filenames and contents of each uStreamer config
file used. For example:
    ```
    uStreamer configuration
    ==> /opt/ustreamer-launcher/configs.d/000-defaults.yml <==
    ---
    ustreamer_encoder: hw
    ustreamer_format: jpeg
    ustreamer_h264_sink: tinypilot::ustreamer::h264
    ustreamer_h264_sink_mode: 777
    ustreamer_h264_sink_rm: true
    ustreamer_interface: 127.0.0.1
    ustreamer_persistent: true
    ustreamer_port: 8001
    ustreamer_resolution: 1920x1080
    ustreamer_desired_fps: 30
    
    ==> /opt/ustreamer-launcher/configs.d/100-tinypilot.yml <==
    ustreamer_desired_fps: 26
    ustreamer_encoder: hw
    ustreamer_format: jpeg
    ustreamer_persistent: true
    ustreamer_port: 8001
    ustreamer_resolution: 1920x1080
    ```

3. Now that we use
[`video_service.restart`](https://github.com/tiny-pilot/tinypilot/blob/68db1dde24a71a1e2a948e0f06a9dd093fde9637/app/api.py#L315)
to apply video settings, our [video settings module looks kind of
awkward](https://github.com/tiny-pilot/tinypilot/blob/68db1dde24a71a1e2a948e0f06a9dd093fde9637/app/video_settings.py).
However, it still made sense to me to keep the default video settings
there.
4. We needed to make [`/home/tinypilot/settings.yml` world readable
(`644`)](https://github.com/tiny-pilot/tinypilot-pro/blob/d77720a744fcfb61fd4ce25864a62d204aa3df64/bundler/bundle/install#L129)
so that the uStreamer launcher could access the file via the newly
created [`100-tinypilot.yml` symbolic
link](https://github.com/tiny-pilot/tinypilot/blob/68db1dde24a71a1e2a948e0f06a9dd093fde9637/debian-pkg/debian/tinypilot.postinst#L13)

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app/api.py

@@ -12,6 +12,7 @@
 import update.settings
 import update.status
 import version
+import video_service
 import video_settings
 
 api_blueprint = flask.Blueprint('api', __name__, url_prefix='/api')
@@ -309,10 +310,8 @@ def settings_video_apply_post():
     """Applies the current video settings found in the settings file.
 
     Returns:
-        Empty response on success, error object otherwise.
+        Empty response.
     """
-    try:
-        video_settings.apply()
-    except video_settings.Error as e:
-        return json_response.error(e), 500
+    video_service.restart()
+
     return json_response.success()

app/static/js/controllers.js

@@ -310,3 +310,17 @@ export async function getLicensingMetadata() {
     redirect: "error",
   }).then(processJsonResponse);
 }
+
+export async function isMjpegStreamAvailable() {
+  try {
+    const response = await fetch("/stream", {
+      method: "HEAD",
+      mode: "same-origin",
+      cache: "no-cache",
+      redirect: "error",
+    });
+    return response.ok;
+  } catch (error) {
+    return false;
+  }
+}

app/templates/custom-elements/video-settings-dialog.html

@@ -160,7 +160,9 @@ <h3>Applying Video Settings</h3>
     getVideoSettings,
     saveVideoSettings,
     applyVideoSettings,
+    isMjpegStreamAvailable,
   } from "/js/controllers.js";
+  import { poll } from "/js/poll.js";
 
   (function () {
     const template = document.querySelector("#video-settings-template");
@@ -445,6 +447,13 @@ <h3>Applying Video Settings</h3>
             h264Bitrate: this._getH264Bitrate(),
           })
             .then(applyVideoSettings)
+            .then(() =>
+              poll({
+                fn: isMjpegStreamAvailable,
+                validate: (isAvailable) => isAvailable,
+                interval: 1000,
+              })
+            )
             .then(() => {
               // Note: After the video stream stops, it doesn't try to
               // reconnect. So in order to restart the video stream, we need to

app/video_settings.py

@@ -1,42 +1,3 @@
-import logging
-import subprocess
-
-_UPDATE_SCRIPT_PATH = '/opt/tinypilot-privileged/scripts/update-video-settings'
 DEFAULT_FRAME_RATE = 30
 DEFAULT_MJPEG_QUALITY = 80
 DEFAULT_H264_BITRATE = 5000
-logger = logging.getLogger(__name__)
-
-
-class Error(Exception):
-    pass
-
-
-class VideoSettingsUpdateError(Error):
-    pass
-
-
-def apply():
-    """Apply the current video settings found in the settings file.
-
-    This runs the ustreamer ansible role using the systemd-config tag.
-
-    Args:
-        None
-
-    Returns:
-        A string consisting of the stdout and stderr output from the
-        update-video-settings script.
-
-    Raises:
-        VideoSettingsUpdateError: If the script exits with a non-zero exit code.
-    """
-    logger.info('Running update-video-settings')
-    try:
-        output = subprocess.check_output(['sudo', _UPDATE_SCRIPT_PATH],
-                                         stderr=subprocess.STDOUT,
-                                         universal_newlines=True)
-    except subprocess.CalledProcessError as e:
-        raise VideoSettingsUpdateError(str(e.output).strip()) from e
-    logger.info('update-video-settings completed successfully')
-    return output

bundler/bundle/install

@@ -126,3 +126,4 @@ ansible-playbook \
 # Persist installation settings.
 cp "${INSTALL_SETTINGS_FILE}" "${TINYPILOT_SETTINGS_FILE}"
 chown tinypilot:tinypilot "${TINYPILOT_SETTINGS_FILE}"
+chmod 0644 "${TINYPILOT_SETTINGS_FILE}"

debian-pkg/debian/tinypilot.postinst

@@ -9,6 +9,8 @@ set -u
 readonly TINYPILOT_USER="tinypilot"
 readonly TINYPILOT_GROUP="tinypilot"
 readonly TINYPILOT_HOME_DIR="/home/${TINYPILOT_USER}"
+readonly TINYPILOT_SETTINGS_FILE="${TINYPILOT_HOME_DIR}/settings.yml"
+readonly USTREAMER_CONFIG_FILE="/opt/ustreamer-launcher/configs.d/100-tinypilot.yml"
 
 # Create tinypilot group if it doesn't already exist.
 getent group "${TINYPILOT_GROUP}" > /dev/null || \
@@ -25,4 +27,12 @@ adduser \
 
 chown -R "${TINYPILOT_USER}:${TINYPILOT_GROUP}" /opt/tinypilot
 
+# Use TinyPilot's settings to override uStreamer's runtime variables.
+if [[ ! -L "${USTREAMER_CONFIG_FILE}" ]]; then
+  ln \
+    --symbolic \
+    "${TINYPILOT_SETTINGS_FILE}" \
+    "${USTREAMER_CONFIG_FILE}"
+fi
+
 #DEBHELPER#

debian-pkg/etc/sudoers.d/tinypilot

@@ -2,7 +2,6 @@ tinypilot ALL=(ALL) NOPASSWD: /opt/tinypilot-privileged/scripts/change-hostname
 tinypilot ALL=(ALL) NOPASSWD: /opt/tinypilot-privileged/scripts/collect-debug-logs
 tinypilot ALL=(ALL) NOPASSWD: /opt/tinypilot-privileged/scripts/read-update-log
 tinypilot ALL=(ALL) NOPASSWD: /opt/tinypilot-privileged/scripts/update
-tinypilot ALL=(ALL) NOPASSWD: /opt/tinypilot-privileged/scripts/update-video-settings
 tinypilot ALL=(ALL) NOPASSWD: /sbin/shutdown
 tinypilot ALL=(ALL) NOPASSWD: /usr/sbin/service janus restart
 tinypilot ALL=(ALL) NOPASSWD: /usr/sbin/service tinypilot-updater start

debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs

@@ -137,7 +137,7 @@ print_info "Checking TinyPilot updater logs..."
 print_info "Checking uStreamer configuration..."
 {
   printf "uStreamer configuration\n"
-  cat /lib/systemd/system/ustreamer.service
+  tail --lines +1 /opt/ustreamer-launcher/configs.d/*
   printf "\n"
 } >> "${LOG_FILE}"