Clean&refactor (#148)

* cleaning spaces and consistent formatting
* removed more subshells
* progress bar cleanup
* moved uservars to a .config file
* rewritten options from yes/no to true/false
* initialized default variables
* added bash options: -euo pipefail, shopt -s nullglob and failglob
* quoting variables, cleaning syntax, logic and order
* unquoted some variables due to breakage
* added exit on pull-fail
* added new sponsor
* added Slack template

notify_templates/notify_slack.sh

@@ -0,0 +1,52 @@
+### DISCLAIMER: This is a third party addition to dockcheck - best effort testing.
+NOTIFY_SLACK_VERSION="v0.1"
+#
+# 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
+
+FromHost=$(hostname)
+
+trigger_notification() {
+    # Modify to fit your setup:
+    AccessToken="xoxb-not-a-real-token-this-will-not-work"
+    ChannelID="C123456"
+    SlackUrl="https://slack.com/api/chat.postMessage"
+
+    curl -sS -o /dev/null --show-error --fail \
+      -d "text=$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
+}