script: add script to automatically update public ip

- add script to automatically update public ip to
  cloudflare DNS record

scripts/update_dns_record.sh

@@ -0,0 +1,107 @@
+#! /usr/bin/env bash
+# This script updates a DNS record using the Cloudflare API.
+set -euo pipefail
+
+function get_my_ip() {
+    curl -s https://api.ipify.org
+}
+
+function get_zone_id() {
+    local zone_name="$1"
+    local api_token="${CLOUDFLARE_API_TOKEN}"
+
+    response=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=${zone_name}" \
+        -H "Content-Type: application/json" \
+        -H "Authorization: Bearer ${api_token}")
+
+    if echo "$response" | grep -q '"success":true'; then
+        echo "$response" | jq -r '.result[0].id'
+    else
+        echo "Failed to retrieve zone ID for ${zone_name}. Response: $response"
+        exit 1
+    fi
+}
+
+function get_dns_record_id() {
+    local zone_id="$1"
+    local api_token="${CLOUDFLARE_API_TOKEN}"
+
+    response=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/${zone_id}/dns_records" \
+        -H "Content-Type: application/json" \
+        -H "Authorization: Bearer ${api_token}")
+
+    if echo "${response}" | grep -q '"success":true'; then
+        for record in $(echo "${response}" | jq -r '.result[] | select(.type=="A") | .id'); do
+            echo "${record}"
+            return
+        done
+    else
+        echo "Failed to retrieve DNS record ID for ${record_name}. Response: $response"
+        exit 1
+    fi
+}
+
+function update_dns_record() {
+    local zone_id="$1"
+    local record_id="$2"
+    local ip_address="$3"
+    local api_token="${CLOUDFLARE_API_TOKEN}"
+
+    local max_attempts=3
+    local attempt=1
+    local success=false
+
+    while [ $attempt -le $max_attempts ] && [ "$success" = false ]; do
+        if response=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/${zone_id}/dns_records/${record_id}" \
+            -H "Content-Type: application/json" \
+            -H "Authorization: Bearer ${api_token}" \
+            -d '{
+                "type": "A",
+                "name": "tahmidcloud.com",
+                "content": "'"${ip_address}"'",
+                "ttl": 1,
+                "proxied": false
+            }'); then
+            if echo "$response" | grep -q '"success":true'; then
+                success=true
+            else
+                echo "Attempt $attempt failed. Response: $response"
+            fi
+        fi
+
+        if [ "$success" = false ] ; then
+            if [ $attempt -lt $max_attempts ]; then
+                echo "Retrying in 5 seconds..."
+                sleep 5
+            fi
+            ((attempt++))
+        fi
+    done
+
+    if [ "$success" = false ]; then
+        echo "Failed to update DNS record after ${max_attempts} attempts"
+        exit 1
+    fi
+    echo "DNS record updated successfully to IP address: ${ip_address}"
+}
+
+function main() {
+    if ! CLOUDFLARE_API_TOKEN=$(grep -A2 'machine api.cloudflare.com' "${HOME}/.netrc" \
+        | grep 'password' | awk '{print $2}'); then
+        echo "Failed to read Cloudflare API token from .netrc file"
+        exit 1
+    fi
+
+    if [ -z "${CLOUDFLARE_API_TOKEN:-}" ]; then
+        echo "CLOUDFLARE_API_TOKEN environment variable is not set."
+        exit 1
+    fi
+
+    zone_id=$(get_zone_id "tahmidcloud.com")
+    record_id=$(get_dns_record_id "${zone_id}")
+    ip_address=$(get_my_ip)
+
+    update_dns_record "${zone_id}" "${record_id}" "${ip_address}"
+}
+
+main