Fix Error handling and reporting for docker OOM

When a docker container exceeds memory limits (OOM status = true) An informative error message will be relayed
to the user.

Have also implemented a test that will trigger OOM errors.

Fixes issues #249 #248

pkg/executor/docker/executor_test.go

@@ -520,5 +520,5 @@ func (s *ExecutorTestSuite) TestDockerOOM() {
 
 	result, err := s.runJob(task, uuid.New().String())
 	require.NoError(s.T(), err)
-	require.Equal(s.T(), "memory limit exceeded", result.ErrorMsg)
+	require.Contains(s.T(), result.ErrorMsg, "memory limit exceeded")
 }

pkg/executor/docker/handler.go

@@ -111,7 +111,7 @@ func (h *executionHandler) run(ctx context.Context) {
 			return
 		}
 		if containerJSON.ContainerJSONBase.State.OOMKilled {
-			containerError = errors.New("memory limit exceeded")
+			containerError = errors.New(`memory limit exceeded. Please refer to https://docs.bacalhau.org/getting-started/resources/#docker-executor for more information`)
 			h.result = &models.RunCommandResult{
 				ExitCode: int(containerExitStatusCode),
 				ErrorMsg: fmt.Sprintf(containerError.Error()),