[solvers] Ipopt supports kPrintFileName (RobotLocomotion#17034)

solvers/BUILD.bazel

@@ -1402,6 +1402,8 @@ drake_cc_googletest(
         ":optimization_examples",
         ":quadratic_program_examples",
         ":second_order_cone_program_examples",
+        "//common:filesystem",
+        "//common:temp_directory",
         "//common/test_utilities:eigen_matrix_compare",
     ] + select({
         "//conditions:default": [

solvers/ipopt_solver.cc

@@ -751,10 +751,20 @@ void SetIpoptOptions(const MathematicalProgram& prog,
   // useful for debugging. Otherwise, we default to printing nothing. The user
   // can always select an arbitrary print level, by setting the ipopt value
   // directly in the solver options.
-  int common_print_level = merged_solver_options.get_print_to_console() ? 4 : 0;
+  const int verbose_level = 4;
+  const int common_print_level =
+      merged_solver_options.get_print_to_console() ? verbose_level : 0;
   SetIpoptOptionsHelper<int>("print_level", common_print_level,
                              &merged_solver_options);
 
+  std::string print_file_name = merged_solver_options.get_print_file_name();
+  if (!print_file_name.empty()) {
+    SetIpoptOptionsHelper<std::string>("output_file", print_file_name,
+                                       &merged_solver_options);
+    SetIpoptOptionsHelper<int>("file_print_level", verbose_level,
+                               &merged_solver_options);
+  }
+
   const auto& ipopt_options_double =
       merged_solver_options.GetOptionsDouble(IpoptSolver::id());
   const auto& ipopt_options_str =

solvers/test/ipopt_solver_test.cc

@@ -2,6 +2,8 @@
 
 #include <gtest/gtest.h>
 
+#include "drake/common/filesystem.h"
+#include "drake/common/temp_directory.h"
 #include "drake/solvers/mathematical_program.h"
 #include "drake/solvers/test/linear_program_examples.h"
 #include "drake/solvers/test/mathematical_program_test_util.h"
@@ -257,6 +259,27 @@ GTEST_TEST(IpoptSolverTest, SolverOptionsVerbosity) {
   }
 }
 
+// This is to verify we can set the print out file through CommonSolverOption.
+GTEST_TEST(IpoptSolverTest, PrintToFile) {
+  MathematicalProgram prog;
+  auto x = prog.NewContinuousVariables(1);
+  prog.AddLinearConstraint(x(0) <= 3);
+  prog.AddLinearConstraint(x(0) >= -3);
+  prog.AddLinearCost(x(0));
+
+  const std::string filename = temp_directory() + "/ipopt.log";
+  EXPECT_FALSE(filesystem::exists({filename}));
+  SolverOptions solver_options;
+  solver_options.SetOption(CommonSolverOption::kPrintFileName, filename);
+
+  IpoptSolver solver;
+  if (solver.is_available()) {
+    const auto result = solver.Solve(prog, {}, solver_options);
+    EXPECT_TRUE(result.is_success());
+    EXPECT_TRUE(filesystem::exists({filename}));
+  }
+}
+
 TEST_P(TestEllipsoidsSeparation, TestSOCP) {
   IpoptSolver ipopt_solver;
   if (ipopt_solver.available()) {