From ae77df9382e40e0cd6ac438075ed3e34ec21f7d1 Mon Sep 17 00:00:00 2001 From: joaks Date: Thu, 18 Apr 2024 19:55:58 +0000 Subject: [PATCH] Provide internal types first Consider the following example: ```go func opts() fx.Option { return fx.Options( fx.WithLogger(func(fx.Lifecycle) fxevent.Logger { return &fxevent.ConsoleLogger{ W: os.Stdout } }), fx.Provide(func() string { return "" }), fx.Provide(func() string { return "" }), ) } func main() { fx.New(opts()).Run() } ``` The relevant issue to surface to the user is that they are double providing the same type. However, the actual error message is: ``` [Fx] ERROR Failed to start: the following errors occurred: - fx.Provide(main.opts.func3()) from: main.opts /home/user/go/src/scratch/fx_provide_order/main.go:17 main.main /home/user/go/src/scratch/fx_provide_order/main.go:22 runtime.main /opt/go/root/src/runtime/proc.go:271 Failed: cannot provide function "main".opts.func3 (/home/user/go/src/scratch/fx_provide_order/main.go:17): cannot provide string from [0]: already provided by "main".opts.func2 (/home/user/go/src/scratch/fx_provide_order/main.go:16) - could not build arguments for function "go.uber.org/fx".(*module).constructCustomLogger.func2 /home/user/go-repos/pkg/mod/go.uber.org/fx@v1.21.0/module.go:292: failed to build fxevent.Logger: missing dependencies for function "main".opts.func1 /home/user/go/src/scratch/fx_provide_order/main.go:11: missing type: - fx.Lifecycle (did you mean to Provide it?) ``` Which contains an additional error related to how the custom logger could not be built. This is because Fx will try to continue to build the custom logger in the face of DI failure, theoretically to report issues through the right channels. But after an error occurs when providing anything, Fx refuses to provide any more types - leading to a subsequent error when trying to build this custom logger that depends on the `fx.Lifecycle` type. This is a common issue that can be misleading for new engineers debugging their fx apps. I couldn't find any particular reason why user-provided provides are registered before these Fx types, se this PR switches this ordering so that custom loggers can still be built if they rely on the Fx types, which cleans up the error message: ``` [Fx] ERROR Failed to start: fx.Provide(main.opts.func3()) from: main.opts /home/user/go/src/scratch/fx_provide_order/main.go:17 main.main /home/user/go/src/scratch/fx_provide_order/main.go:22 runtime.main /opt/go/root/src/runtime/proc.go:271 Failed: cannot provide function "main".opts.func3 (/home/user/go/src/scratch/fx_provide_order/main.go:17): cannot provide string from [0]: already provided by "main".opts.func2 (/home/user/go/src/scratch/fx_provide_order/main.go:16) ``` --- app.go | 8 ++++---- app_test.go | 25 ++++++++++++++++++++++++- module_test.go | 10 +++++----- 3 files changed, 33 insertions(+), 10 deletions(-) diff --git a/app.go b/app.go index 8ede19eb5..244c402ce 100644 --- a/app.go +++ b/app.go @@ -480,10 +480,6 @@ func New(opts ...Option) *App { m.build(app, app.container) } - for _, m := range app.modules { - m.provideAll() - } - frames := fxreflect.CallerStack(0, 0) // include New in the stack for default Provides app.root.provide(provide{ Target: func() Lifecycle { return app.lifecycle }, @@ -492,6 +488,10 @@ func New(opts ...Option) *App { app.root.provide(provide{Target: app.shutdowner, Stack: frames}) app.root.provide(provide{Target: app.dotGraph, Stack: frames}) + for _, m := range app.modules { + m.provideAll() + } + // Run decorators before executing any Invokes -- including the one // inside constructCustomLogger. app.err = multierr.Append(app.err, app.root.decorateAll()) diff --git a/app_test.go b/app_test.go index 2ac6ef2bf..aa4b1172e 100644 --- a/app_test.go +++ b/app_test.go @@ -113,7 +113,30 @@ func TestNewApp(t *testing.T) { []string{"Provided", "Provided", "Provided", "Provided", "LoggerInitialized", "Started"}, spy.EventTypes()) - assert.Contains(t, spy.Events()[0].(*fxevent.Provided).OutputTypeNames, "struct {}") + // Lifecycle, Shutdowner, and DotGraph are indices 0, 1, and 2. + // Our type should be index 3. + assert.Contains(t, spy.Events()[3].(*fxevent.Provided).OutputTypeNames, "struct {}") + }) + + t.Run("InternalTypesProvidedFirst", func(t *testing.T) { + t.Parallel() + + // Test that internal types get provided before + // user-specified types. This increases the chance + // that custom loggers relying on internal types + // can be built successfully. + + spy := new(fxlog.Spy) + app := fxtest.New(t, Provide(func() struct{} { return struct{}{} }), + WithLogger(func() fxevent.Logger { return spy })) + defer app.RequireStart().RequireStop() + require.Equal(t, + []string{"Provided", "Provided", "Provided", "Provided", "LoggerInitialized", "Started"}, + spy.EventTypes()) + + assert.Contains(t, spy.Events()[0].(*fxevent.Provided).OutputTypeNames, "fx.Lifecycle") + assert.Contains(t, spy.Events()[1].(*fxevent.Provided).OutputTypeNames, "fx.Shutdowner") + assert.Contains(t, spy.Events()[2].(*fxevent.Provided).OutputTypeNames, "fx.DotGraph") }) t.Run("CircularGraphReturnsError", func(t *testing.T) { diff --git a/module_test.go b/module_test.go index 1a6fd9b71..3ac20527b 100644 --- a/module_test.go +++ b/module_test.go @@ -261,7 +261,7 @@ func TestModuleSuccess(t *testing.T) { desc: "custom logger for module", giveWithLogger: fx.NopLogger, wantEvents: []string{ - "Supplied", "Provided", "Provided", "Provided", + "Provided", "Provided", "Provided", "Supplied", "Run", "LoggerInitialized", "Invoking", "Invoked", }, }, @@ -269,7 +269,7 @@ func TestModuleSuccess(t *testing.T) { desc: "Not using a custom logger for module defaults to app logger", giveWithLogger: fx.Options(), wantEvents: []string{ - "Supplied", "Provided", "Provided", "Provided", "Provided", "Run", + "Provided", "Provided", "Provided", "Supplied", "Provided", "Run", "LoggerInitialized", "Invoking", "Run", "Invoked", "Invoking", "Invoked", }, }, @@ -660,7 +660,7 @@ func TestModuleFailures(t *testing.T) { giveAppOpts: spyAsLogger, wantErrContains: []string{"error building logger"}, wantEvents: []string{ - "Supplied", "Provided", "Provided", "Provided", "Run", + "Provided", "Provided", "Provided", "Supplied", "Run", "LoggerInitialized", "Provided", "LoggerInitialized", }, }, @@ -678,7 +678,7 @@ func TestModuleFailures(t *testing.T) { giveAppOpts: spyAsLogger, wantErrContains: []string{"error building logger dependency"}, wantEvents: []string{ - "Supplied", "Provided", "Provided", "Provided", "Run", + "Provided", "Provided", "Provided", "Supplied", "Run", "LoggerInitialized", "Provided", "Provided", "Run", "LoggerInitialized", }, }, @@ -690,7 +690,7 @@ func TestModuleFailures(t *testing.T) { "fx.WithLogger", "from:", "Failed", }, wantEvents: []string{ - "Supplied", "Provided", "Provided", "Provided", "Run", + "Provided", "Provided", "Provided", "Supplied", "Run", "LoggerInitialized", "Provided", "LoggerInitialized", }, },