Elasticsearch-py: Cannot catch exceptions during connect

[tlinhart]

I'm trying to connect to Elasticsearch cluster and handle possible errors with this code (nodes' IP addresses are intentionally incorrect):

connected = False
try:
    elastic = elasticsearch.Elasticsearch(['192.168.1.1', '192.168.1.2'])
    connected = elastic.ping()
except Exception:
    pass
if not connected:
    print('Connection to Elasticsearch failed')
    sys.exit(1)

Even though the error message is printed and program exists, exceptions are not caught and stack trace is printed before the error message:

HEAD http://192.168.1.1:9200/ [status:N/A request:0.001s]
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 137, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/elasticsearch/connection/http_urllib3.py", line 114, in perform_request
    response = self.pool.urlopen(method, url, body, retries=False, headers=self.headers, **kw)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 609, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 224, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/usr/lib/python3/dist-packages/six.py", line 686, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 559, in urlopen
    body=body, headers=headers)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 353, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/usr/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 162, in connect
    conn = self._new_conn()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 146, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f659b0b0080>: Failed to establish a new connection: [Errno 111] Connection refused
Connection <Urllib3HttpConnection: http://192.168.1.1:9200> has failed for 1 times in a row, putting on 60 second timeout.
HEAD http://192.168.1.2:9200/ [status:N/A request:2.999s]
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 137, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
OSError: [Errno 113] No route to host

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/elasticsearch/connection/http_urllib3.py", line 114, in perform_request
    response = self.pool.urlopen(method, url, body, retries=False, headers=self.headers, **kw)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 609, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 224, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/usr/lib/python3/dist-packages/six.py", line 686, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 559, in urlopen
    body=body, headers=headers)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 353, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/usr/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 162, in connect
    conn = self._new_conn()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 146, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f659b0b00f0>: Failed to establish a new connection: [Errno 113] No route to host
Connection <Urllib3HttpConnection: http://192.168.1.2:9200> has failed for 1 times in a row, putting on 60 second timeout.
HEAD http://192.168.1.1:9200/ [status:N/A request:0.001s]
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 137, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/elasticsearch/connection/http_urllib3.py", line 114, in perform_request
    response = self.pool.urlopen(method, url, body, retries=False, headers=self.headers, **kw)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 609, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 224, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/usr/lib/python3/dist-packages/six.py", line 686, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 559, in urlopen
    body=body, headers=headers)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 353, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/usr/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 162, in connect
    conn = self._new_conn()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 146, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f659b0b0358>: Failed to establish a new connection: [Errno 111] Connection refused
Connection <Urllib3HttpConnection: http://192.168.1.1:9200> has failed for 2 times in a row, putting on 120 second timeout.
HEAD http://192.168.1.2:9200/ [status:N/A request:2.998s]
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 137, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
OSError: [Errno 113] No route to host

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/elasticsearch/connection/http_urllib3.py", line 114, in perform_request
    response = self.pool.urlopen(method, url, body, retries=False, headers=self.headers, **kw)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 609, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 224, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/usr/lib/python3/dist-packages/six.py", line 686, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 559, in urlopen
    body=body, headers=headers)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 353, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/usr/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 162, in connect
    conn = self._new_conn()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 146, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f659b0b0cf8>: Failed to establish a new connection: [Errno 113] No route to host
Connection <Urllib3HttpConnection: http://192.168.1.2:9200> has failed for 2 times in a row, putting on 120 second timeout.
Connection to Elasticsearch failed

I would like to suppress the stack trace and handle connection error myself with just the error message. I thought try/catch block would suffice, but obvisouly there's something I'm missing.

[HonzaKral]

The ping method deliberately catches all exceptions and only returns True/False whether it has been successful. If you wish to handle the error yourself you need to use any other API, I suggest .info() which is cheap and has no side effects.

Alternatively you can just make use of the ping functionality and exit your program if ping() returns False.

Hope this helps!

[tlinhart]

The problem is that ping() doesn't catch exceptions as illustrated above. It produces trackback even though it's inside try/catch. If I could just call ping() and get True or False, it would be sufficient and I would be more than happy. Calling info() behaves the same - even if it's inside try/catch, it produces a traceback if unsuccessful.

[HonzaKral]

The traceback is only logged using python's standard logging module, to disable it configure your logging and set the proper logging level for the elasticsearch logger, shortcut, to disable all non-ERROR level messages is:

import logging
logging.basicConfig(level=logging.ERROR)

[tlinhart]

That's it, many thanks. Didn't know it's just being logged.

[sentient-soellingeraj]

Any idea what is the right connection timeout value when establishing the connection with the Elasticsearch server? Or, can you suggest a general approach to setting the timeout correctly to allow the connection to be established if possible, while minimizing the time cost if it's not possible?