Merge #3114

3114: Improve waiting for SSH r=townsend2010 a=ricab

Two main changes to improve the step of waiting for SSH, when starting/launching instances:

1. Increase the time allotted for each iteration of the loop to wait for SSH, to 1 second. Log each such iteration of the loop.
2. Retry only on specific exceptions, logging them (with `trace` verbosity, since this happens every second), and letting the rest through, in the hope that this may shed some light into cases where instances end up in unknown state.



Co-authored-by: Ricardo Abreu <ricardo.abreu@canonical.com>

include/multipass/exceptions/internal_timeout_exception.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) Canonical, Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef MULTIPASS_INTERNAL_TIMEOUT_EXCEPTION_H
+#define MULTIPASS_INTERNAL_TIMEOUT_EXCEPTION_H
+
+#include <chrono>
+#include <stdexcept>
+#include <string>
+
+#include <multipass/format.h>
+
+namespace multipass
+{
+
+class InternalTimeoutException : public std::runtime_error
+{
+public:
+    InternalTimeoutException(const std::string& action, std::chrono::milliseconds timeout)
+        : std::runtime_error{fmt::format("Could not {} within {}ms", action, timeout.count())}
+    {
+    }
+};
+
+} // namespace multipass
+
+#endif // MULTIPASS_INTERNAL_TIMEOUT_EXCEPTION_H

include/multipass/exceptions/ip_unavailable_exception.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) Canonical, Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef MULTIPASS_IP_UNAVAILABLE_EXCEPTION_H
+#define MULTIPASS_IP_UNAVAILABLE_EXCEPTION_H
+
+#include <stdexcept>
+#include <string>
+
+namespace multipass
+{
+
+class IPUnavailableException : public std::runtime_error
+{
+    using std::runtime_error::runtime_error;
+};
+
+} // namespace multipass
+
+#endif // MULTIPASS_IP_UNAVAILABLE_EXCEPTION_H

src/platform/backends/shared/shared_backend_utils.h

@@ -18,6 +18,7 @@
 #ifndef MULTIPASS_SHARED_BACKEND_UTILS_H
 #define MULTIPASS_SHARED_BACKEND_UTILS_H
 
+#include <multipass/exceptions/internal_timeout_exception.h>
 #include <multipass/exceptions/start_exception.h>
 #include <multipass/utils.h>
 #include <multipass/virtual_machine.h>
@@ -50,9 +51,9 @@ std::string ip_address_for(VirtualMachine* virtual_machine, Callable&& get_ip, s
             }
         };
 
-        auto on_timeout = [virtual_machine] {
+        auto on_timeout = [virtual_machine, &timeout] {
             virtual_machine->state = VirtualMachine::State::unknown;
-            throw std::runtime_error("failed to determine IP address");
+            throw InternalTimeoutException{"determine IP address", timeout};
         };
 
         utils::try_action_for(on_timeout, timeout, action);

src/utils/utils.cpp

@@ -18,6 +18,8 @@
 #include <multipass/constants.h>
 #include <multipass/exceptions/autostart_setup_exception.h>
 #include <multipass/exceptions/exitless_sshprocess_exception.h>
+#include <multipass/exceptions/internal_timeout_exception.h>
+#include <multipass/exceptions/ip_unavailable_exception.h>
 #include <multipass/exceptions/sshfs_missing_error.h>
 #include <multipass/file_ops.h>
 #include <multipass/format.h>
@@ -75,6 +77,15 @@ QString find_autostart_target(const QString& subdir, const QString& autostart_fi
 
     return target_path;
 }
+
+template <typename ExceptionT>
+mp::utils::TimeoutAction log_and_retry(const ExceptionT& e, const mp::VirtualMachine* vm,
+                                       mpl::Level log_level = mpl::Level::trace)
+{
+    assert(vm);
+    mpl::log(log_level, vm->vm_name, e.what());
+    return mp::utils::TimeoutAction::retry;
+};
 } // namespace
 
 mp::Utils::Utils(const Singleton<Utils>::PrivatePass& pass) noexcept : Singleton<Utils>::Singleton{pass}
@@ -312,23 +323,38 @@ bool mp::utils::valid_mac_address(const std::string& mac)
 void mp::utils::wait_until_ssh_up(VirtualMachine* virtual_machine, std::chrono::milliseconds timeout,
                                   std::function<void()> const& ensure_vm_is_running)
 {
+    static constexpr auto wait_step = 1s;
     mpl::log(mpl::Level::debug, virtual_machine->vm_name, "Waiting for SSH to be up");
+
     auto action = [virtual_machine, &ensure_vm_is_running] {
         ensure_vm_is_running();
         try
         {
-            mp::SSHSession session{virtual_machine->ssh_hostname(1ms), virtual_machine->ssh_port()};
+            mp::SSHSession session{virtual_machine->ssh_hostname(wait_step), virtual_machine->ssh_port()};
 
             std::lock_guard<decltype(virtual_machine->state_mutex)> lock{virtual_machine->state_mutex};
             virtual_machine->state = VirtualMachine::State::running;
             virtual_machine->update_state();
             return mp::utils::TimeoutAction::done;
         }
-        catch (const std::exception&)
+        catch (const InternalTimeoutException& e)
         {
-            return mp::utils::TimeoutAction::retry;
+            return log_and_retry(e, virtual_machine);
+        }
+        catch (const SSHException& e)
+        {
+            return log_and_retry(e, virtual_machine);
+        }
+        catch (const IPUnavailableException& e)
+        {
+            return log_and_retry(e, virtual_machine);
+        }
+        catch (const std::runtime_error& e) // transitioning away from catching generic runtime errors
+        {                                   // TODO remove once we're confident this is an anomaly
+            return log_and_retry(e, virtual_machine, mpl::Level::warning);
         }
     };
+
     auto on_timeout = [virtual_machine] {
         std::lock_guard<decltype(virtual_machine->state_mutex)> lock{virtual_machine->state_mutex};
         virtual_machine->state = VirtualMachine::State::unknown;