Update: systemd-timers notes and examples

notes/linux/systemd_timers.md

@@ -13,6 +13,12 @@ Generally there are 3 pieces to a timer
 systemd-analyze calendar *-*-* *:10,20:10
 ```
 
+Time is in the format:
+
+```
+DayOfWeek Year-Month-Day Hour:Minute:Second
+```
+
 To find suitable targets for things like `Wants` and `After`, see
 `systemd.special(7)`. If you want to check the current status of your targets,
 use:
@@ -28,8 +34,8 @@ Scripts should be put in `/usr/local/bin` if they can be run by anyone or
 `/usr/local/sbin` if they should only be run by root
 
 Define a `xxx.service` file in `/etc/systemd/system`. Set the timer as one of
-its `Wants`. `network.target` may be more appropriate in some cases.
-`multi-user.target` is a good default for `WantedBy`
+its `Wants`. `network.target` may be more appropriate in some cases. Do not add
+an `[Install]` section, as your timer already handles that
 
 ```systemd
 [Unit]
@@ -41,9 +47,6 @@ After = network.target
 [Service]
 Type = oneshot
 ExecStart = /usr/local/bin/broadcast_ip.sh
-
-[Install]
-WantedBy = multi-user.target
 ```
 
 Now you'll need a timer file. It's easiest to make it have the same name as the

systemd/system/timer-scripts/template.set_a_records.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+declare wan_ip_record wan_ip cf_records host_record cf_host_ip cf_rec_id
+
+declare -r HOST=<your-subdomain>
+declare -r DOMAIN=<your-domain-name>
+declare -r TOKEN=<your-api-token>
+declare -r ZONE_ID=<this-zones-id>
+
+#╔─────────────────────────────────────────────────────────────────────────────╗
+#│ Gετ WΛN IP                                                                  |
+#╚─────────────────────────────────────────────────────────────────────────────╝
+if ! wan_ip_record="$(host -W2 myip.opendns.com resolver1.opendns.com)"; then
+  echo "Hosts timed out" >&2
+  exit 1
+fi
+
+wan_ip="$(echo "$wan_ip_record" | tail -n1 | awk '{ split($0, a, " "); print a[4] }')"
+
+#╔─────────────────────────────────────────────────────────────────────────────╗
+#│ Gετ Λ rεcδrd δη Clδμdflαrε                                                  |
+#╚─────────────────────────────────────────────────────────────────────────────╝
+if ! cf_records="$(curl -s --request GET \
+  --url https://api.cloudflare.com/client/v4/zones/${ZONE_ID}/dns_records \
+  --header 'Content-Type: application/json' \
+  --header "Authorization: Bearer $TOKEN")"
+then
+  echo "Failed to retrive cloudflare zone records" >&2
+  exit 1
+fi
+
+for i in {0..4000}; do  # Assuming 4000 is enough
+  record="$(echo "$cf_records" | jq --raw-output ".result[${i}].name")"
+
+  if [[ "$record" == "${HOST}.${DOMAIN}" ]]; then
+    host_record="$(echo "$cf_records" | jq -r ".result[${i}]")"
+    break
+  elif [[ "$record" == null ]]; then
+    echo "No record found for ${HOST}.${DOMAIN}" >&2
+    exit 1
+  fi
+done
+
+#╔─────────────────────────────────────────────────────────────────────────────╗
+#│ Sετ Λ rεcδrd τδ cμrrεητ WΛN                                                 |
+#╚─────────────────────────────────────────────────────────────────────────────╝
+cf_host_ip="$(echo "$host_record" | jq -r '.content')"
+cf_rec_id="$(echo "$host_record" | jq -r '.id')"
+
+if [[ -z "$cf_host_ip" || "$cf_host_ip" == null ]]; then
+  echo "Failed to find content of A record for ${HOST}.${DOMAIN}" >&2
+  exit 1
+elif [[ -z "$cf_rec_id" || "$cf_rec_id" == null ]]; then
+  echo "Failed to find A record ID for ${HOST}.${DOMAIN}" >&2
+  exit 1
+fi
+
+if [[ "$cf_host_ip" == "$wan_ip" ]]; then
+  echo "Cloudflare is up to date @ $(date)" >&2
+else
+  echo "Updating Cloudflare's A record from $cf_host_ip to $wan_ip" >&2
+
+  patch_response="$(curl -s --request PATCH \
+      --url "https://api.cloudflare.com/client/v4/zones/${ZONE_ID}/dns_records/${cf_rec_id}" \
+      --header 'Content-Type: application/json' \
+      --header "Authorization: Bearer $TOKEN" \
+      --data '{
+      "comment": "'"${HOST} @ $(date)"'",
+      "content": "'"$wan_ip"'",
+      "name": "'"${HOST}.${DOMAIN}"'",
+      "proxied": false,
+      "ttl": 1
+    }')"
+
+  if [[ "$(echo "$patch_response" | jq -r '.success')" == true ]]; then
+    echo "Update to $wan_ip succeeded @ $(date)" >&2
+  else
+    echo "Failed to update A record. DUMP:"
+    echo "$patch_response"
+    exit 1
+  fi
+fi

systemd/system/update_a_record.service

@@ -0,0 +1,12 @@
+[Unit]
+Description = Sends current ip address to uni servers
+Wants = update_a_record.timer
+Wants = network-online.target
+After = network-online.target
+
+[Service]
+Type = oneshot
+ExecStart = /usr/local/bin/set_a_records.sh
+
+[Install]
+WantedBy = multi-user.target

systemd/system/update_a_record.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Updates Cloudflare's A record for mirrorside.mami2.moe
+Requires=update_a_record.service
+
+[Timer]
+Unit=update_a_record.service
+OnCalendar=*-*-* *:00,15,30,45:00
+RandomizedDelaySec=15min
+
+[Install]
+WantedBy=timers.target

systemd/system/ydotoold.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=ydotool daemon
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/ydotoold
+
+[Install]
+WantedBy=default.target