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Asynchronous Python client for InfluxDB

Project description

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Asynchronous Python client for InfluxDB. Built on top of aiohttp and asyncio.

InfluxDB is an open-source distributed time series database. Find more about InfluxDB at http://influxdata.com/

Installation

To install the latest release:

$ pip install aioinflux
$ pip install aioinflux[pandas]  # For DataFrame parsing support

The library is still in beta, so you may also want to install the latest version from the development branch:

$ pip install git+https://github.com/plugaai/aioinflux@dev

Dependencies

Aioinflux supports Python 3.6+ ONLY. For older Python versions please use the official Python client. However, there is some discussion regarding Pypy/Python 3.5 support.

The main third-party library dependency is aiohttp, for all HTTP request handling. and pandas for DataFrame reading/writing support.

There are currently no plans to support other HTTP libraries besides aiohttp. If aiohttp + asyncio is not your soup, see Alternatives.

Usage

TL;DR:

This sums most of what you can do with aioinflux:

import asyncio
from aioinflux import InfluxDBClient

point = {
    'time': '2009-11-10T23:00:00Z',
    'measurement': 'cpu_load_short',
    'tags': {'host': 'server01',
             'region': 'us-west'},
    'fields': {'value': 0.64}
}

async def main():
    client = InfluxDBClient(db='testdb')
    await client.create_database(db='testdb')
    await client.write(point)
    resp = await client.query('SELECT value FROM cpu_load_short')
    print(resp)


asyncio.get_event_loop().run_until_complete(main())

Client modes

Despite the library’s name, InfluxDBClient can also run in non-async mode (a.k.a blocking) mode. It can be useful for debugging and exploratory data analysis.

The running mode for can be switched on-the-fly by changing the mode attribute:

client = InfluxDBClient(mode='blocking')
client.mode = 'async'

The blocking mode is implemented through a decorator that automatically runs coroutines on the event loop as soon as they are generated. Usage is almost the same as in the async mode, but without the need of using await and being able to run from outside of a coroutine function:

client = InfluxDBClient(db='testdb', mode='blocking')
client.ping()
client.write(point)
client.query('SELECT value FROM cpu_load_short')

Writing data

Input data can be:

  1. A string properly formatted in InfluxDB’s line protocol
  2. A mapping (e.g. dictionary) containing the following keys: measurement, time, tags, fields
  3. A Pandas DataFrame with a DatetimeIndex
  4. An iterable of one of the above

Input data in formats 2-4 are parsed into the line protocol before being written to InfluxDB. All parsing functionality is located in the serialization.py module. Beware that serialization is not highly optimized (cythonization PRs are welcome!) and may become a bottleneck depending on your application. It is however, reasonably faster than InfluxDB’s official Python client.

The write method returns True when successful and raises an InfluxDBError otherwise.

Writing dictionary-like objects

Aioinflux accepts any dictionary-like object (mapping) as input. However, that dictionary must be properly formatted and contain the following keys:

  1. measurement: Optional. Must be a string-like object. If omitted, must be specified when calling InfluxDBClient.write by passing a measurement argument.
  2. time: Optional. The value can be datetime.datetime, date-like string (e.g., 2017-01-01, 2009-11-10T23:00:00Z) or anything else that can be parsed by Pandas’ Timestamp class initializer (or ciso8601 if Pandas is not available). See below for details. Use of ISO 8601 compliant strings is highly recommended.
  3. tags: Optional. This must contain another mapping of field names and values. Both tag keys and values should be strings.
  4. fields: Mandatory. This must contain another mapping of field names and values. Field keys should be strings. Field values can be float, int, str, bool or None or any its subclasses. Attempting to use Numpy types will cause errors as np.int64, np.float64, etc are not subclasses of Python’s builti-in numeric types. Use dataframes for writing data using Numpy types.

Any fields other then the above will be ignored when writing data to InfluxDB.

A typical dictionary-like point would look something like the following:

{'time': '2009-11-10T23:00:00Z',
'measurement': 'cpu_load_short',
'tags': {'host': 'server01', 'region': 'us-west'},
'fields': {'value1': 0.64, 'value2': True, 'value3': 10}}
Note on timestamps and timezones

Working with timezones in computing tends to be quite messy. To avoid such problems, the broadly agreed upon idea is to store timestamps in UTC. This is how both InfluxDB and Pandas treat timestamps internally.

Pandas and many other libraries also assume all input timestamps are in UTC unless otherwise explicitly noted. Aioinflux does the same and assumes any timezone-unaware datetime object or datetime-like strings is in UTC. Aioinflux does not raise any warnings when timezone-unaware input is passed and silently assumes it to be in UTC.

Writing DataFrames

Aioinflux also accepts Pandas dataframes as input. The only requirements for the dataframe is that the index must be of type DatetimeIndex. Also, any column whose dtype is object will be converted to a string representation.

A typical dataframe input should look something like the following:

                                       LUY       BEM       AJW tag
2017-06-24 08:45:17.929097+00:00  2.545409  5.173134  5.532397   B
2017-06-24 10:15:17.929097+00:00 -0.306673 -1.132941 -2.130625   E
2017-06-24 11:45:17.929097+00:00  0.894738 -0.561979 -1.487940   B
2017-06-24 13:15:17.929097+00:00 -1.799512 -1.722805 -2.308823   D
2017-06-24 14:45:17.929097+00:00  0.390137 -0.016709 -0.667895   E

The measurement name must be specified with the measurement argument when calling InfluxDBClient.write. Columns of dtype pd.Categorical will be automatically treated as tags. Columns whose dtype is not pd.Categorical but should be treated as tags must be specified by passing a sequence as the tag_columns argument. Additional tags (not present in the actual dataframe) can also be passed using arbitrary keyword arguments.

Example:

client = InfluxDBClient(db='testdb', mode='blocking')
client.write(df, measurement='prices', tag_columns=['tag'], asset_class='equities')

In the example above, df is the dataframe we are trying to write to InfluxDB and measurement is the measurement we are writing to.

tag_columns is in an optional iterable telling which of the dataframe columns should be parsed as tag values. If tag_columns is not explicitly passed, all columns in the dataframe whose dtype is not pd.Categorical will be treated as InfluxDB field values.

Any other keyword arguments passed to InfluxDBClient.write are treated as extra tags which will be attached to the data being written to InfluxDB. Any string which is a valid InfluxDB identifier and valid Python identifier can be used as an extra tag key (with the exception of the strings data, measurement and tag_columns).

See InfluxDBClient.write docstring for details.

Querying data

Querying data is as simple as passing an InfluxDB query string to InfluxDBClient.query:

client.query('SELECT myfield FROM mymeasurement')

The result (in blocking and async modes) is a dictionary containing the parsed JSON data returned by the InfluxDB HTTP API:

{'results': [{'series': [{'columns': ['time', 'Price', 'Volume'],
     'name': 'mymeasurement',
     'values': [[1491963424224703000, 5783, 100],
      [1491963424375146000, 5783, 200],
      [1491963428374895000, 5783, 100],
      [1491963429645478000, 5783, 1100],
      [1491963429655289000, 5783, 100],
      [1491963437084443000, 5783, 100],
      [1491963442274656000, 5783, 900],
      [1491963442274657000, 5782, 5500],
      [1491963442274658000, 5781, 3200],
      [1491963442314710000, 5782, 100]]}],
   'statement_id': 0}]}

Output formats

When querying data, InfluxDBClient can return data in one of the following formats:

  1. raw: Default. Returns the a dictionary containing the JSON response received from InfluxDB.
  2. iterable: Wraps the JSON response in a InfluxDBResult or InfluxDBChunkedResult object. This object main purpose is to facilitate iteration of data. See Iterating responses for details.
  3. dataframe: Parses the result into a Pandas dataframe or a dictionary of dataframes. See Retrieving DataFrames for details.

The output format for can be switched on-the-fly by changing the output attribute:

client = InfluxDBClient(output='dataframe')
client.mode = 'raw'

Retrieving DataFrames

When the client is in dataframe mode, InfluxDBClient.query will return a Pandas DataFrame:

                                  Price  Volume
2017-04-12 02:17:04.224703+00:00   5783     100
2017-04-12 02:17:04.375146+00:00   5783     200
2017-04-12 02:17:08.374895+00:00   5783     100
2017-04-12 02:17:09.645478+00:00   5783    1100
2017-04-12 02:17:09.655289+00:00   5783     100
2017-04-12 02:17:17.084443+00:00   5783     100
2017-04-12 02:17:22.274656+00:00   5783     900
2017-04-12 02:17:22.274657+00:00   5782    5500
2017-04-12 02:17:22.274658+00:00   5781    3200
2017-04-12 02:17:22.314710+00:00   5782     100

When generating dataframes, InfluxDB types are mapped to the following Numpy/Pandas dtypes:

InfluxDB type Dataframe column dtype
Float float64
Integer int64
String object
String (tag values) CategoricalDtype
Boolean bool
Timestamp datetime64

Chunked responses

Aioinflux supports InfluxDB chunked queries. Passing chunked=True when calling InfluxDBClient.query, returns an AsyncGenerator object, which can asynchronously iterated. Using chunked requests allows response processing to be partially done before the full response is retrieved, reducing overall query time.

chunks = await client.query("SELECT * FROM mymeasurement", chunked=True)
async for chunk in chunks:
    # do something
    await process_chunk(...)

Chunked responses are not supported when using the dataframe output format.

Iterating responses

By default, InfluxDBClient.query returns a parsed JSON response from InfluxDB. In order to easily iterate over that JSON response point by point, Aioinflux provides the iterpoints function, which returns a generator object:

from aioinflux import iterpoints

r = client.query('SELECT * from h2o_quality LIMIT 10')
for i in iterpoints(r):
    print(i)
[1439856000000000000, 41, 'coyote_creek', '1']
[1439856000000000000, 99, 'santa_monica', '2']
[1439856360000000000, 11, 'coyote_creek', '3']
[1439856360000000000, 56, 'santa_monica', '2']
[1439856720000000000, 65, 'santa_monica', '3']

iterpoints can also be used with chunked responses:

chunks = await client.query('SELECT * from h2o_quality', chunked=True)
async for chunk in chunks:
    for point in iterpoints(chunk):
        # do something

By default, the generator returned by iterpoints yields a plain list of values without doing any expensive parsing. However, in case a specific format is needed, an optional parser argument can be passed. parser is a function that takes the raw value list for each data point and an additional metadata dictionary containing all or a subset of the following: {'columns', 'name', 'tags', 'statement_id'}.

r = await client.query('SELECT * from h2o_quality LIMIT 5')
for i in iterpoints(r, lambda x, meta: dict(zip(meta['columns'], x))):
    print(i)
{'time': 1439856000000000000, 'index': 41, 'location': 'coyote_creek', 'randtag': '1'}
{'time': 1439856000000000000, 'index': 99, 'location': 'santa_monica', 'randtag': '2'}
{'time': 1439856360000000000, 'index': 11, 'location': 'coyote_creek', 'randtag': '3'}
{'time': 1439856360000000000, 'index': 56, 'location': 'santa_monica', 'randtag': '2'}
{'time': 1439856720000000000, 'index': 65, 'location': 'santa_monica', 'randtag': '3'}

Besides being explicitly with a raw response, iterpoints is also be used “automatically” by InfluxDBResult and InfluxDBChunkedResult when using iterable mode:

client.output = 'iterable'
# Returns InfluxDBResult object
r = client.query('SELECT * from h2o_quality LIMIT 10')
for i in r:
    # do something

# Returns InfluxDBChunkedResult object
r = await client.query('SELECT * from h2o_quality', chunked=True)
async for i in r:
    # do something

# Returns InfluxDBChunkedResult object
r = await client.query('SELECT * from h2o_quality', chunked=True)
async for chunk in r.iterchunks():
    # do something with JSON chunk

Getting tag key/value info

In order to properly parse dataframes, InfluxDBClient internally uses the get_tag_info, which basically sends a series of SHOW TAG KEYS and SHOW TAG VALUES queries and gathers key/value information for all measurements of the active database in a dictionary.

Query patterns

Aioinflux provides a wrapping mechanism around InfluxDBClient.query in order to provide convenient access to commonly used query patterns.

Query patterns are query strings containing optional named “replacement fields” surrounded by curly braces {}, just as in str_format(). Replacement field values are defined by keyword arguments when calling the method associated with the query pattern. Differently from plain str_format(), positional arguments are also supported and can be mixed with keyword arguments.

Aioinflux built-in query patterns are defined here. Users can also dynamically define additional query patterns by using the InfluxDBClient.set_query_pattern helper function. User-defined query patterns have the disadvantage of not being shown for auto-completion in IDEs such as Pycharm. However, they do show up in dynamic environments such as Jupyter. If you have a query pattern that you think will used by many people and should be built-in, please submit a PR.

Built-in query pattern examples:

client.create_database(db='foo')   # CREATE DATABASE {db}
client.drop_measurement('bar')     # DROP MEASUREMENT {measurement}'
client.show_users()                # SHOW USERS

# Positional and keyword arguments can be mixed
client.show_tag_values_from('bar', key='spam')  # SHOW TAG VALUES FROM {measurement} WITH key = "{key}"

Please refer to InfluxDB documentation for further query-related information.

Other functionality

Authentication

Aioinflux supports basic HTTP authentication provided by aiohttp.BasicAuth. Simply pass username and password when instantiating InfluxDBClient:

client = InfluxDBClient(username='user', password='pass)

Unix domain sockets

If your InfluxDB server uses UNIX domain sockets you can use unix_socket when instantiating InfluxDBClient:

client = InfluxDBClient(unix_socket='/path/to/socket')

See aiohttp.UnixConnector for details.

HTTPS/SSL

Aioinflux/InfluxDB use HTTP by default, but HTTPS can be used by passing ssl=True when instantiating InfluxDBClient:

client = InfluxDBClient(host='my.host.io', ssl=True)

Database selection

After the instantiation of the InfluxDBClient object, database can be switched by changing the db attribute:

client = InfluxDBClient(db='db1')
client.db = 'db2'

Beware that differently from some NoSQL databases (such as MongoDB), InfluxDB requires that a databases is explicitly created (by using the CREATE DATABASE query) before doing any operations on it.

Debugging

If you are having problems while using Aioinflux, enabling logging might be useful.

Below is a simple way to setup logging from your application:

import logging

logging.basicConfig()
logging.getLogger('aioinflux').setLevel(logging.DEBUG)

For further information about logging, please refer to the official documentation.

Implementation

Since InfluxDB exposes all its functionality through an HTTP API, InfluxDBClient tries to be nothing more than a thin and simple wrapper around that API.

The InfluxDB HTTP API exposes exactly three endpoints/functions: ping, write and query.

InfluxDBClient merely wraps these three functions and provides some parsing functionality for generating line protocol data (when writing) and parsing JSON responses (when querying).

Additionally, partials are used in order to provide convenient access to commonly used query patterns. See the Query patterns section for details.

Contributing

To contribute, fork the repository on GitHub, make your changes and submit a pull request.
Aioinflux is not a mature project yet, so just simply raising issues is also greatly appreciated :)

Alternatives

  • InfluxDB-Python: The official blocking-only client. Based on Requests.
  • influx-sansio: Fork of aioinflux using curio/trio and asks as a backend.

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