fail-monitor/monitor.cpp

// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright 2017 IBM Corporation

#include "monitor.hpp"

#include <phosphor-logging/log.hpp>

namespace phosphor
{
namespace unit
{
namespace failure
{

using namespace phosphor::logging;

constexpr auto failedState = "failed";
constexpr auto startMethod = "StartUnit";
constexpr auto stopMethod = "StopUnit";

constexpr auto systemdService = "org.freedesktop.systemd1";
constexpr auto systemdObjPath = "/org/freedesktop/systemd1";
constexpr auto systemdInterface = "org.freedesktop.systemd1.Manager";
constexpr auto systemdPropertyInterface = "org.freedesktop.DBus.Properties";
constexpr auto systemdUnitInterface = "org.freedesktop.systemd1.Unit";

void Monitor::analyze()
{
    if (inFailedState(getSourceUnitPath()))
    {
        runTargetAction();
    }
}

bool Monitor::inFailedState(const std::string& path)
{
    std::variant<std::string> property;

    auto method = bus.new_method_call(systemdService, path.c_str(),
                                      systemdPropertyInterface, "Get");

    method.append(systemdUnitInterface, "ActiveState");

    try
    {
        auto reply = bus.call(method);

        reply.read(property);
    }
    catch (const sdbusplus::exception_t&)
    {
        log<level::ERR>("Failed reading ActiveState DBus property",
                        entry("UNIT=%s", source.c_str()));
        throw;
    }

    auto value = std::get<std::string>(property);
    return (value == failedState);
}

std::string Monitor::getSourceUnitPath()
{
    sdbusplus::message::object_path path;

    auto method = bus.new_method_call(systemdService, systemdObjPath,
                                      systemdInterface, "GetUnit");
    method.append(source);

    try
    {
        auto reply = bus.call(method);
        reply.read(path);
    }
    catch (const sdbusplus::exception_t&)
    {
        log<level::ERR>("Failed GetUnit DBus method call",
                        entry("UNIT=%s", source.c_str()));
        throw;
    }

    return static_cast<std::string>(path);
}

void Monitor::runTargetAction()
{
    // Start or stop the target unit
    const auto* methodCall =
        (action == Action::start) ? startMethod : stopMethod;

    log<level::INFO>("The source unit is in failed state, "
                     "running target action",
                     entry("SOURCE=%s", source.c_str()),
                     entry("TARGET=%s", target.c_str()),
                     entry("ACTION=%s", methodCall));

    auto method = this->bus.new_method_call(systemdService, systemdObjPath,
                                            systemdInterface, methodCall);
    method.append(target);
    method.append("replace");

    try
    {
        auto reply = bus.call(method);
    }
    catch (const sdbusplus::exception_t&)
    {
        log<level::ERR>("Failed to run action on the target unit",
                        entry("UNIT=%s", target.c_str()));
        throw;
    }
}
} // namespace failure
} // namespace unit
} // namespace phosphor