Refactor notifications and add helper functions (#182)

* Refactor notifications and add helper functions

* Add helper functions to simplify sourcing files and executing functions if they exist

* Create notify_v2.sh wrapper script

* Simplify and consolidate notification logic within notify_v2.sh

* Support notification management via environment variables

* Move secrets to dockcheck.config

* Fix NOTIFY_CHANNELS default value when not set

* Feedback changes

* Remove leading spaces from MessageBody

* Check for valid notify v2 variables

* Warn on missing configuration and bypass notifications

* Update readme

* Additional feedback fixes

* More comments in default.config with different # depth for comments and settings

* Rename NOTIFY_TOPIC_NAME variable to NTFY_TOPIC_NAME for consistency

* Add TELEGRAM_TOPIC_ID

* Fix AppriseURL variable

* Add an ending newline to all MessageBody statements for consistency

* Remove troubleshooting echo statement

* Prevent attempting to trigger notifications for notification templates if versions are the same

---------

Co-authored-by: Matthew Oleksowicz <matt@everyoneneeds.it>

notify_templates/notify_slack.sh

@@ -1,52 +1,22 @@
 ### DISCLAIMER: This is a third party addition to dockcheck - best effort testing.
-NOTIFY_SLACK_VERSION="v0.1"
+NOTIFY_SLACK_VERSION="v0.2"
 #
-# Copy/rename this file to notify.sh in the same directory as dockcheck.sh to enable the notification snippet.
-# Setu app and token at https://api.slack.com/tutorials/tracks/posting-messages-with-curl
-# Add your AccessToken and ChannelID below
+# Setup app and token at https://api.slack.com/tutorials/tracks/posting-messages-with-curl
+# Do not modify this file directly. Set SLACK_ACCESS_TOKEN, and SLACK_CHANNEL_ID in your dockcheck.config file.
 
-FromHost=$(hostname)
+if [[ -z "${SLACK_ACCESS_TOKEN:-}" ]] || [[ -z "${SLACK_CHANNEL_ID:-}" ]]; then
+  printf "Slack notification channel enabled, but required configuration variables are missing. Slack notifications will not be sent.\n"
 
-trigger_notification() {
-    # Modify to fit your setup:
-    AccessToken="xoxb-not-a-real-token-this-will-not-work"
-    ChannelID="C123456"
-    SlackUrl="https://slack.com/api/chat.postMessage"
+  remove_channel slack
+fi
 
-    curl -sS -o /dev/null --show-error --fail \
-      -d "text=$MessageBody" -d "channel=$ChannelID" \
-      -H "Authorization: Bearer $AccessToken" \
-      -X POST $SlackUrl
-}
-
-send_notification() {
-    [ -s "$ScriptWorkDir"/urls.list ] && releasenotes || Updates=("$@")
-    UpdToString=$( printf '%s\\n' "${Updates[@]}" )
-
-    printf "\nSending Slack notification\n"
-
-    MessageTitle="$FromHost - updates available."
-    # Setting the MessageBody variable here.
-    printf -v MessageBody "🐋 Containers on $FromHost with updates available:\n$UpdToString"
-
-    trigger_notification
-}
-
-### Rename (eg. disabled_dockcheck_notification), remove or comment out the following function
-### to not send notifications when dockcheck itself has updates.
-dockcheck_notification() {
-    printf "\nSending Slack dockcheck notification\n"
-
-    MessageTitle="$FromHost - New version of dockcheck available."
-    # Setting the MessageBody variable here.
-    printf -v MessageBody "Installed version: $1 \nLatest version: $2 \n\nChangenotes: $3"
-
-    RawNotifyUrl="https://raw.githubusercontent.com/mag37/dockcheck/main/notify_templates/notify_slack.sh"
-    LatestNotifyRelease="$(curl -s -r 0-150 $RawNotifyUrl | sed -n "/NOTIFY_SLACK_VERSION/s/NOTIFY_SLACK_VERSION=//p" | tr -d '"')"
-    if [[ "$NOTIFY_SLACK_VERSION" != "$LatestNotifyRelease" ]] ; then
-        printf -v NotifyUpdate "\n\nnotify_slack.sh update avialable:\n $NOTIFY_SLACK_VERSION -> $LatestNotifyRelease\n"
-        MessageBody="${MessageBody}${NotifyUpdate}"
-    fi
-
-    trigger_notification
+trigger_slack_notification() {
+  AccessToken="${SLACK_ACCESS_TOKEN}" # e.g. SLACK_ACCESS_TOKEN=some-token
+  ChannelID="${SLACK_CHANNEL_ID}" # e.g. CHANNEL_ID=mychannel
+  SlackUrl="https://slack.com/api/chat.postMessage"
+
+  curl -sS -o /dev/null --show-error --fail \
+    -d "text=$MessageBody" -d "channel=$ChannelID" \
+    -H "Authorization: Bearer $AccessToken" \
+    -X POST $SlackUrl
 }