Why Adding a Server with OAT Breaks yum and How to Fix It

1. Fault Description

When adding a server via OAT (OceanBase Automation Tool) version 4.4.0, the yum command becomes unavailable, producing the error:

bash: /usr/bin/yum: /usr/bin/python: bad interpreter: No such file or directory

The OAT task also reports a dependency‑installation failure and suggests using the oat.server.ignore_deps parameter to skip it.

2. Error Analysis

Manual execution on the target host confirms that yum fails with the same interpreter error, indicating that OAT altered the Python environment. Inspecting the OAT script reveals a loop that processes package‑command pairs. For entries where pkg matches python, the script runs: yum install --nogpgcheck -y $pkg Because the host’s default /usr/bin/python points to a non‑existent interpreter (or to /usr/bin/python3 which is missing), the subsequent yum invocation fails.

The script’s conditional logic checks

if [[ "$pkg" == "python2" && "$python_version" =~ ^2 ]] || [[ "$pkg" == "python3" && "$python_version" =~ ^3 ]]; then

, but when pkg is simply python, the condition never matches, leading to an unconditional yum install --nogpgcheck -y python. This replaces the system Python with the version from the yum repository, breaking the interpreter link.

3. Solution Methods

Method 1 – Modify the OAT script

Change the condition to compare against python instead of python2 / python3:

if [[ "$pkg" == "python" && "$python_version" =~ ^2 ]] || [[ "$pkg" == "python" && "$python_version" =~ ^3 ]]; then

Re‑run the OAT task; the script will now skip the unnecessary yum install python step.

Method 2 – Restore a valid Python interpreter

Replace the broken /usr/bin/python with a working binary, e.g. link it to the existing Python 2 interpreter:

rm -f /usr/bin/python && ln -s /usr/bin/python2 /usr/bin/python

Alternatively, create a symlink for /usr/bin/python3 pointing to the Python 2 binary if only Python 2 is present:

ln -s /usr/bin/python2 /usr/bin/python3

4. Appendix – Full OAT Script Extract

os_type=centos7_or_uosc
final_exit_code=0
install_failed_deps=""
if [[ "$os_type" =~ ^(centos7_or_uosc|redhat9_or_rocky9|kylin_like)$ ]]; then
    for cmd_pkg in mysql:mariadb python:python ifconfig:net-tools mtr:mtr tar:tar strings:binutils dig:bind-utils :libaio curl:curl :libatomic nc:nc ip:iproute gdb:gdb sar:sysstat perf:perf top:procps-ng asar:antsar
    do
        cmd=$(echo "$cmd_pkg" | cut -d':' -f1)
        pkg=$(echo "$cmd_pkg" | cut -d':' -f2)
        if [[ "$pkg" == "antsar" ]]; then
            if ! rpm --quiet --query antsar; then
                rpm -i /tmp/antsar-2.1.9-20250905115440.alios7.x86_64.rpm.y82oIAzZ.rpm
                tmp_exit_code=$?
                if [[ $tmp_exit_code != 0 ]]; then
                    final_exit_code=$tmp_exit_code
                    install_failed_deps="$install_failed_deps $pkg"
                fi
            fi
        elif [[ "$pkg" =~ ^python ]]; then
            python_version=$(python -V 2>&1 | awk '{print $2}')
            if [[ "$pkg" == "python2" && "$python_version" =~ ^2 ]] || [[ "$pkg" == "python3" && "$python_version" =~ ^3 ]]; then
                continue
            fi
            yum install --nogpgcheck -y $pkg
            tmp_exit_code=$?
            if [[ $tmp_exit_code != 0 ]]; then
                final_exit_code=$tmp_exit_code
                install_failed_deps="$install_failed_deps $pkg"
            else
                python_version=$(python -V 2>&1 | awk '{print $2}')
                if [[ "$pkg" == "python2" ]]; then
                    if ! echo "$python_version"|grep -q "^2"; then
                        alternatives --install /usr/bin/python python /usr/bin/python2 1
                    fi
                else
                    if ! echo "$python_version"|grep -q "^3"; then
                        alternatives --install /usr/bin/python python /usr/bin/python3 1
                    fi
                fi
            fi
        else
            if [[ -n "$cmd" ]] && which "$cmd" >/dev/null 2>&1; then
                continue
            fi
            yum install --nogpgcheck -y $pkg
            tmp_exit_code=$?
            if [[ $tmp_exit_code != 0 ]]; then
                final_exit_code=$tmp_exit_code
                install_failed_deps="$install_failed_deps $pkg"
            fi
        fi
    done
fi
if [[ $final_exit_code != 0 ]]; then
    echo "Install deps${install_failed_deps} failed. If you are sure that the dependencies that failed to install are not needed, you can ignore them by specifying the system parameter oat.server.ignore_deps" >&2
fi
exit $final_exit_code

Technical reference: https://github.com/actiontech/sqle