fix: logs for tasks (#2499)

## Description
This PR manipulates `run_sh` and `run_python` logic to stream logs from
the command or python script thats being executed on the container. This
also allows retrieving task logs after a run has finished, whereas
before, task containers would not return logs from `kurtosis service
logs`.

An improvement to this would be to enable streaming back logs via run
output so users don't have to go through Docker Desktop or docker cli to
view logs from a long running task that might have err'd.

https://www.loom.com/share/89181c37442048b9bdc746bfd37fe2ec

## Is this change user facing?
YES

core/server/api_container/server/startosis_engine/kurtosis_instruction/tasks/run_python.go

@@ -320,7 +320,7 @@ func (builtin *RunPythonCapabilities) Execute(ctx context.Context, _ *builtin_ar
 	if err != nil {
 		return "", stacktrace.Propagate(err, "error occurred while preparing the sh command to execute on the image")
 	}
-	fullCommandToRun := []string{shellWrapperCommand, "-c", commandToRun}
+	fullCommandToRun := getCommandToRunForStreamingLogs(commandToRun)
 
 	// run the command passed in by user in the container
 	runPythonExecutionResult, err := executeWithWait(ctx, builtin.serviceNetwork, builtin.name, builtin.wait, fullCommandToRun)
@@ -418,7 +418,7 @@ func getPythonCommandToRun(builtin *RunPythonCapabilities) (string, error) {
 	argumentsAsString := strings.Join(maybePythonArgumentsWithRuntimeValueReplaced, spaceDelimiter)
 	runEscaped := strings.ReplaceAll(builtin.run, `"`, `\"`)
 	if len(argumentsAsString) > 0 {
-		return fmt.Sprintf(`python -c "%s" %s`, runEscaped, argumentsAsString), nil
+		return fmt.Sprintf(`python -u -c "%s" %s`, runEscaped, argumentsAsString), nil
 	}
-	return fmt.Sprintf(`python -c "%s"`, runEscaped), nil
+	return fmt.Sprintf(`python -u -c "%s"`, runEscaped), nil
 }

core/server/api_container/server/startosis_engine/kurtosis_instruction/tasks/run_sh.go

@@ -276,7 +276,7 @@ func (builtin *RunShCapabilities) Execute(ctx context.Context, _ *builtin_argume
 	if err != nil {
 		return "", stacktrace.Propagate(err, "error occurred while preparing the sh command to execute on the image")
 	}
-	fullCommandToRun := []string{shellWrapperCommand, "-c", commandToRun}
+	fullCommandToRun := getCommandToRunForStreamingLogs(commandToRun)
 
 	// run the command passed in by user in the container
 	createDefaultDirectoryResult, err := executeWithWait(ctx, builtin.serviceNetwork, builtin.name, builtin.wait, fullCommandToRun)

core/server/api_container/server/startosis_engine/kurtosis_instruction/tasks/tasks_shared.go

@@ -50,14 +50,24 @@ const (
 	runFilesArtifactsKey = "files_artifacts"
 
 	shellWrapperCommand = "/bin/sh"
+	taskLogFilePath     = "/tmp/kurtosis-task.log"
 	noNameSet           = ""
 	uniqueNameGenErrStr = "error occurred while generating unique name for the file artifact"
 
 	//  enables init mode on containers; cleaning up any zombie processes
 	tiniEnabled = true
 )
 
-var runTailCommandToPreventContainerToStopOnCreating = []string{"tail", "-f", "/dev/null"}
+var runCommandToStreamTaskLogs = []string{shellWrapperCommand, "-c", fmt.Sprintf("touch %s && tail -F %s", taskLogFilePath, taskLogFilePath)}
+
+// Wraps [commandToRun] to enable streaming logs from tasks.
+// Uses curly braces to execute the command(s) in the current shell.
+// Adds an extra echo to ensure each log ends with a newline.
+// Uses tee to direct output to the task log file while maintaining output to stdout.
+// Redirects stderr to stdout.
+func getCommandToRunForStreamingLogs(commandToRun string) []string {
+	return []string{shellWrapperCommand, "-c", fmt.Sprintf("{ %v; } %v %v %v %v %v %v %v %v", commandToRun, "2>&1", "|", "tee", taskLogFilePath, "&&", "echo", ">>", taskLogFilePath)}
+}
 
 func parseStoreFilesArg(serviceNetwork service_network.ServiceNetwork, arguments *builtin_argument.ArgumentValuesSet) ([]*store_spec.StoreSpec, *startosis_errors.InterpretationError) {
 	var result []*store_spec.StoreSpec
@@ -276,7 +286,7 @@ func getServiceConfig(
 	filesArtifactExpansion *service_directory.FilesArtifactsExpansion,
 	envVars *map[string]string,
 ) (*service.ServiceConfig, error) {
-	serviceConfig, err := service.CreateServiceConfig(maybeImageName, maybeImageBuildSpec, maybeImageRegistrySpec, maybeNixBuildSpec, nil, nil, runTailCommandToPreventContainerToStopOnCreating, nil, *envVars, filesArtifactExpansion, nil, 0, 0, service_config.DefaultPrivateIPAddrPlaceholder, 0, 0, map[string]string{}, nil, nil, map[string]string{}, image_download_mode.ImageDownloadMode_Missing, tiniEnabled)
+	serviceConfig, err := service.CreateServiceConfig(maybeImageName, maybeImageBuildSpec, maybeImageRegistrySpec, maybeNixBuildSpec, nil, nil, runCommandToStreamTaskLogs, nil, *envVars, filesArtifactExpansion, nil, 0, 0, service_config.DefaultPrivateIPAddrPlaceholder, 0, 0, map[string]string{}, nil, nil, map[string]string{}, image_download_mode.ImageDownloadMode_Missing, tiniEnabled)
 	if err != nil {
 		return nil, stacktrace.Propagate(err, "An error occurred creating service config")
 	}