ZFS Send Backup

#!/bin/bash

# Load environment variables from the .env file
export $(grep -v '^#' "$(dirname "$0")/../.env" | xargs)

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# Variables
SOURCE_POOL="nas"
BACKUP_POOL="backup-ssd"
DATASET="immich"
SNAPSHOT_NAME="daily-$(date +%Y-%m-%d)"
SNAPSHOT_PATTERN="@daily-"
TELEGRAM_MESSAGE="📢 *Immich Backup*%0A%0ASnapshot: $SNAPSHOT_NAME%0A%0A"

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# Function to accumulate messages
append_message() {
    local MESSAGE="$1"
    TELEGRAM_MESSAGE+="$MESSAGE%0A"
}

# Function to send telegram message
send_telegram_message() {
    local MESSAGE="$1"
    $TELEGRAM_MESSAGE_SCRIPT "$TELEGRAM_MESSAGE" "$TELEGRAM_ZFS_TOKEN" "$TELEGRAM_ZFS_CHAT_ID"
}

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# Record the start time
START_TIME=$(date +%s)

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# Check if the snapshot exists
SNAPSHOT_OUTPUT=$(zfs list -t snapshot | grep "$SOURCE_POOL/$DATASET@$SNAPSHOT_NAME" 2>&1)
SNAPSHOT_STATUS=$?

# Check if the command was successful
if [ $SNAPSHOT_STATUS -eq 0 ]; then
    append_message "✅ Snapshot found"
else
    append_message "❌ Snapshot not found"
fi

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# Try to unmount before sending snapshot
if [ "$(zfs get -H -o value mounted "$BACKUP_POOL/$DATASET")" = "yes" ]; then
    UNMOUNT_OUTPUT=$(zfs unmount "$BACKUP_POOL/$DATASET" 2>&1)
    UNMOUNT_STATUS=$?

    # Check if the command was successful
    if [ $UNMOUNT_STATUS -eq 0 ]; then
        append_message "✅ Unmounted filesystem"
    else
        append_message "❌ Failed to unmount"
    fi
else
    append_message "🔹 Unmount not executed"
fi

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if [ $UNMOUNT_STATUS -eq 0 ]; then
    # Get the latest snapshot on the source pool
    LATEST_SOURCE_SNAPSHOT=$(zfs list -H -t snapshot -o name -S creation "$SOURCE_POOL/$DATASET" | head -n 1)

    # Get all snapshots on source pool sorted by creation time
    ALL_SOURCE_SNAPSHOTS=($(zfs list -t snapshot -o name -s creation | grep "$SOURCE_DATASET@"))

    # Determine the oldest snapshot from the source
    OLDEST_SOURCE_SNAPSHOT="${ALL_SOURCE_SNAPSHOTS[0]}"

    # Get the latest snapshot on the destination pool
    LATEST_BACKUP_SNAPSHOT=$(zfs list -H -t snapshot -o name -S creation "$BACKUP_POOL/$DATASET" 2>/dev/null | grep $SNAPSHOT_PATTERN | head -n 1)

    # Ensure the source has at least one snapshot
    if [[ -z "$LATEST_SOURCE_SNAPSHOT" ]]; then
        append_message "❌ No snapshots found"
    fi

    # If the destination has no snapshots, a full send is required
    if [[ -z "$LATEST_BACKUP_SNAPSHOT" ]]; then
        append_message "⚠️ No previous snapshot"
        append_message "🔹 Manually equalize"
    fi

    # Extract the snapshot names
    LATEST_SOURCE_NAME="${LATEST_SOURCE_SNAPSHOT#*@}"
    LATEST_BACKUP_NAME="${LATEST_BACKUP_SNAPSHOT#*@}"

    # If the latest snapshots are the same, no transfer is needed
    if [[ "$LATEST_SOURCE_NAME" == "$LATEST_BACKUP_NAME" ]]; then
        append_message "✅ Snapshots are already synced"
    else
        # Send incremental backup
        SEND_OUTPUT=$( { zfs send -i "$SOURCE_POOL/$DATASET@$LATEST_BACKUP_NAME" "$SOURCE_POOL/$DATASET@$LATEST_SOURCE_NAME" | zfs receive -F "$BACKUP_POOL/$DATASET"; } 2>&1 )
        SEND_STATUS=$?

        # Check if the command was successful
        if [[ $SEND_STATUS -eq 0 ]]; then
            append_message "✅ Transferred snapshot"
        else
            append_message "❌ Error transferring partial backup"
        fi
    fi

    # Get the logicalreferenced values
    SOURCE_LOGICAL=$(zfs list -o logicalreferenced "$SOURCE_POOL/$DATASET" | awk 'NR==2 {print $1}')
    BACKUP_LOGICAL=$(zfs list -o logicalreferenced "$BACKUP_POOL/$DATASET" | awk 'NR==2 {print $1}')

    # Compare values
    if [[ "$SOURCE_LOGICAL" == "$BACKUP_LOGICAL" ]]; then
        append_message "✅ Backup is identical"
    else
        append_message "❌ Backup is not identical"
    fi
else
    append_message "🔹 Transferring not executed"
fi

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# Remount the dataset
if [ "$(zfs get -H -o value mounted "$BACKUP_POOL/$DATASET")" != "yes" ]; then
    MOUNT_OUTPUT=$(zfs mount "$BACKUP_POOL/$DATASET" 2>&1)
    MOUNT_STATUS=$?

    if [ "$MOUNT_STATUS" -eq 0 ]; then
        append_message "✅ Remounted filesystem"
    else
        append_message "❌ Remounted failed"
    fi
else
    append_message "🔹 Remounted not executed"
fi

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# Record the end time
END_TIME=$(date +%s)

# Calculate total execution time in seconds
ELAPSED_TIME=$((END_TIME - START_TIME))

# Convert to minutes and seconds format
MINUTES=$((ELAPSED_TIME / 60))
SECONDS=$((ELAPSED_TIME % 60))

# Append execution time to the message log
append_message "%0A⏳ Total time: ${MINUTES}m ${SECONDS}s"

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# Append backup size
TOTAL_SIZE=$(zfs list -o logicalreferenced "$SOURCE_POOL/$DATASET" | awk 'NR==2 {print $1}')
append_message "📂 Total size: $TOTAL_SIZE"

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# Append snapshots total size
SNAPSHOTS_TOTAL_SIZE=$(zfs get -Hp usedbysnapshots | awk '{s+=$3} END {printf "%.2fG\n", s/(1024*1024*1024)}')
append_message "📸 Snapshots size: $SNAPSHOTS_TOTAL_SIZE"

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# Append unmount output logs to the message log
if [[ $UNMOUNT_STATUS -ne 0 ]]; then
    append_message "%0A\`\`\`Error $UNMOUNT_OUTPUT\`\`\`"
fi

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# Append send output logs to the message log
if [[ $SEND_STATUS -ne 0 ]]; then
    append_message "%0A\`\`\`Error $SEND_OUTPUT\`\`\`"
fi

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# Append mount output logs to the message log
if [[ $MOUNT_STATUS -ne 0 ]]; then
    append_message "%0A\`\`\`Error $MOUNT_OUTPUT\`\`\`"
fi

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# Send the telegram message
send_telegram_message