set binlog config in mysql

keep max binlog file size to 100M. and rotate then in 10 days

setup/start.sh

@@ -178,7 +178,11 @@ systemctl start nginx
 # restart mysql to make sure it has latest config
 if [[ ! -f /etc/mysql/mysql.cnf ]] || ! diff -q "${script_dir}/start/mysql.cnf" /etc/mysql/mysql.cnf >/dev/null; then
     # wait for all running mysql jobs
-    cp "${script_dir}/start/mysql.cnf" /etc/mysql/mysql.cnf
+    if [[ "${ubuntu_version}" == "20.04" ]]; then
+        cp "${script_dir}/start/mysql/8.0.cnf" /etc/mysql/mysql.cnf
+    else
+        cp "${script_dir}/start/mysql/5.7.cnf" /etc/mysql/mysql.cnf
+    fi
     while true; do
         if ! systemctl list-jobs | grep mysql; then break; fi
         echo "Waiting for mysql jobs..."