From e5b720aadbaebabbd76ec3aecac21ddf643eb8c0 Mon Sep 17 00:00:00 2001
From: Shaun Setlock <shaunsetlock@protonmail.com>
Date: Sun, 19 Jun 2022 16:11:44 -0400
Subject: [PATCH] Created the required files to setup systemd units for
 autostart.

---
 systemd/dht-start-restart'@pimonitoring1 |  1 +
 systemd/dht-start-restart@.service       | 20 ++++++++++++++++++++
 systemd/notes.md                         | 16 ++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 systemd/dht-start-restart'@pimonitoring1
 create mode 100644 systemd/dht-start-restart@.service
 create mode 100644 systemd/notes.md

diff --git a/systemd/dht-start-restart'@pimonitoring1 b/systemd/dht-start-restart'@pimonitoring1
new file mode 100644
index 0000000..3d09941
--- /dev/null
+++ b/systemd/dht-start-restart'@pimonitoring1
@@ -0,0 +1 @@
+PATH_TO_FILE=/home/pi/dht22/main.py
diff --git a/systemd/dht-start-restart@.service b/systemd/dht-start-restart@.service
new file mode 100644
index 0000000..a3a391a
--- /dev/null
+++ b/systemd/dht-start-restart@.service
@@ -0,0 +1,20 @@
+# Unit file template for creating auto start and restart of python script for dht sensor.
+# Template should be in /etc/systemd/system/dht-start-restart@.service
+# Environment Variables for each instances should be at /etc/default/dht-start-restart@%i
+# Enable with `systemctl enable --now remote-tunnel@%i`
+# where %i is the name of the pimonitoring instance (e.g. pimonitoring1)
+#
+[Unit]
+Description=Start python script for DHT22 sensor on %I
+After=network.target
+
+[Service]
+User=pi
+EnvironmentFile=/etc/default/dht-start-restart@%i
+ExecStart=/usr/bin/python3 ${PATH_TO_FILE}
+RestartSec=15
+Restart=always
+KillMode=mixed
+
+[Install]
+WantedBy=multi-user.target
diff --git a/systemd/notes.md b/systemd/notes.md
new file mode 100644
index 0000000..fb061df
--- /dev/null
+++ b/systemd/notes.md
@@ -0,0 +1,16 @@
+# Creating systemd unit for Auto Start/Restart
+### The steps below outline the process for creating a systemd service unit.
+### This service will automatically start the python script.
+
+## Procedure
+
+1. Create the service template by copying `dht-start-restart@.service` into `/etc/systemd/system/`.
+2. Define environment variables for an instance of this template by copying `dht-start-restart@pimonitoring1` into `/etc/default/`.
+    - __NOTE__: The instance should replace the name of the RPiZW. (e.g. pimonitoring2, etc.)
+3. Create the instance and enable it with `sudo systemctl enable --now dht-start-restart@pimonitoring1`
+    - __NOTE__: It may be required to reload the systemd daemon. `sudo systemctl reload-daemon`
+
+## Common Issues
+ - [ ] Is the `User=` in `dht-start-restart@.service` correct? pi vs. shaun
+ - [ ] Is the `{PATH_TO_FILE}` in `dht-start-restart@pimonitoring1` correct? `/home/pi` vs. `/home/shaun`
+ - [ ] Does the python script `main.py` contain any relative paths?