socket.gaierror: [Errno -2] Name or service not known urllib.error.URLError: <urlopen error [Errno -2] Name or service not known>

Question

I was looking this tutorial on how to implement convolutional neural networks.

I followed the instructions there so now I have this code:

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function  
import numpy as np # linear algebra
import pandas as pd # data processing, CSV file I/O (e.g. pd.read_csv)    
from subprocess import check_output
print(check_output(["ls", "../input"]).decode("utf8"))   
import tensorflow as tf    
from tensorflow.contrib import learn
from tensorflow.contrib.learn.python.learn.estimators import model_fn as model_fn_lib

tf.logging.set_verbosity(tf.logging.INFO)

def cnn_model_fn(features, labels, mode):
  """Model function for CNN."""
  # Input Layer
  input_layer = tf.reshape(features, [-1, 28, 28, 1])

  # Convolutional Layer #1
  conv1 = tf.layers.conv2d(
      inputs=input_layer,
      filters=32,
      kernel_size=[5, 5],
      padding="same",
      activation=tf.nn.relu)

  # Pooling Layer #1
  pool1 = tf.layers.max_pooling2d(inputs=conv1, pool_size=[2, 2], strides=2)

  # Convolutional Layer #2 and Pooling Layer #2
  conv2 = tf.layers.conv2d(
      inputs=pool1,
      filters=64,
      kernel_size=[5, 5],
      padding="same",
      activation=tf.nn.relu)
  pool2 = tf.layers.max_pooling2d(inputs=conv2, pool_size=[2, 2], strides=2)

  # Dense Layer
  pool2_flat = tf.reshape(pool2, [-1, 7 * 7 * 64])
  dense = tf.layers.dense(inputs=pool2_flat, units=1024, activation=tf.nn.relu)
  dropout = tf.layers.dropout(
      inputs=dense, rate=0.4, training=mode == learn.ModeKeys.TRAIN)

  # Logits Layer
  logits = tf.layers.dense(inputs=dropout, units=10)

  loss = None
  train_op = None

  # Calculate Loss (for both TRAIN and EVAL modes)
  if mode != learn.ModeKeys.INFER:
    onehot_labels = tf.one_hot(indices=tf.cast(labels, tf.int32), depth=10)
    loss = tf.losses.softmax_cross_entropy(
        onehot_labels=onehot_labels, logits=logits)

  # Configure the Training Op (for TRAIN mode)
  if mode == learn.ModeKeys.TRAIN:
    train_op = tf.contrib.layers.optimize_loss(
        loss=loss,
        global_step=tf.contrib.framework.get_global_step(),
        learning_rate=0.001,
        optimizer="SGD")

  # Generate Predictions
  predictions = {
      "classes": tf.argmax(
          input=logits, axis=1),
      "probabilities": tf.nn.softmax(
          logits, name="softmax_tensor")
  }

  # Return a ModelFnOps object
  return model_fn_lib.ModelFnOps(
      mode=mode, predictions=predictions, loss=loss, train_op=train_op)


def main():
    print("In main")
    # Load training and eval data
    mnist = learn.datasets.load_dataset("mnist")
    train_data = tf.train.string_input_producer(tf.train.match_filenames_once("../inputs/train/*.jpg")) # Returns np.array
    train_labels = np.asarray(train_labels.csv, dtype=np.float32)
    test_data = tf.train.string_input_producer(tf.train.match_filenames_once("../inputs/test/*.jpg")) # Returns np.array
    # eval_labels = np.asarray(mnist.test.labels, dtype=np.int32)


    # Create the Estimator
    mnist_classifier = learn.Estimator(
          model_fn=cnn_model_fn, model_dir="/tmp/mnist_convnet_model")

    # Set up logging for predictions
    tensors_to_log = {"probabilities": "softmax_tensor"}
    logging_hook = tf.train.LoggingTensorHook(
      tensors=tensors_to_log, every_n_iter=50)


    mnist_classifier.fit(
        x=train_data,
        y=train_labels,
        batch_size=100,
        steps=20000,
        monitors=[logging_hook])

    # Configure the accuracy metric for evaluation
    metrics = {
        "accuracy":
            learn.MetricSpec(
                metric_fn=tf.metrics.accuracy, prediction_key="classes"),
    }


    # Evaluate the model and print results
    eval_results = mnist_classifier.evaluate(
        x=eval_data, y=eval_labels, metrics=metrics)
    print(eval_results)

main()

For this code, I am getting this error:

Traceback (most recent call last):
  File "/opt/conda/lib/python3.6/urllib/request.py", line 1318, in do_open
10.0s
3
    encode_chunked=req.has_header('Transfer-encoding'))
  File "/opt/conda/lib/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/opt/conda/lib/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/opt/conda/lib/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/opt/conda/lib/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/opt/conda/lib/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/opt/conda/lib/python3.6/http/client.py", line 1392, in connect
    super().connect()
  File "/opt/conda/lib/python3.6/http/client.py", line 936, in connect
    (self.host,self.port), self.timeout, self.source_address)
  File "/opt/conda/lib/python3.6/socket.py", line 704, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/opt/conda/lib/python3.6/socket.py", line 743, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "../src/script.py", line 130, in <module>
    main()
  File "../src/script.py", line 93, in main
    mnist = learn.datasets.load_dataset("mnist")
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/__init__.py", line 73, in load_dataset
10.1s
4
    return DATASETS[name]()
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/mnist.py", line 279, in load_mnist
10.2s
5
    return read_data_sets(train_dir)
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/mnist.py", line 235, in read_data_sets
    SOURCE_URL + TRAIN_IMAGES)
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/base.py", line 208, in maybe_download
10.2s
6
    temp_file_name, _ = urlretrieve_with_retry(source_url)
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/base.py", line 165, in wrapped_fn
    return fn(*args, **kwargs)
  File "/opt/conda/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/datasets/base.py", line 190, in urlretrieve_with_retry
    return urllib.request.urlretrieve(url, filename)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 248, in urlretrieve
    with contextlib.closing(urlopen(url, data)) as fp:
  File "/opt/conda/lib/python3.6/urllib/request.py", line 223, in urlopen
10.2s
7
    return opener.open(url, data, timeout)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/opt/conda/lib/python3.6/urllib/request.py", line 1320, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [Errno -2] Name or service not known>

This message seems very unclear to me. Any idea what could be the cause of this?

Answer 1

Seems like your script is failing in this line:

mnist = learn.datasets.load_dataset("mnist")

because it can't find the mnist dataset locally (on disk), tries to download it, but it (for some reason) can not.

Try downloading that dataset to MNIST-data directory (Check the source for load_dataset(), which calls load_mnist() with default train_dir='MNIST-data'. Eventually, read_data_sets tries do load train/test images/labels from disk, but if not found in ./MNIST-data, tries to download them from train-images-idx3-ubyte.gz, etc.)

Answer 2

The error is because of this line mnist = learn.datasets.load_dataset("mnist") which is trying to download the mnist dataset. But i don't see mnist being used in your code. So you can comment it if your not not using the dataset. Or if you want to use it you can download it from http://yann.lecun.com/exdb/mnist/ (all the four files) and put the path of the directory files in: mnist = learn.datasets.load_dataset("/path/to/mnist").