Tentaclio

Python library that simplifies:

• Handling streams from different protocols such as file:, ftp:, sftp:, s3:, ...
• Opening database connections.
• Managing the credentials in distributed systems.

Main considerations in the design:

• Easy to use: all streams are open via tentaclio.open, all database connections through tentaclio.db.
• URLs are the basic resource locator and db connection string.
• Automagic authentication for protected resources.
• Extensible: you can add your own handlers for other schemes.
• Pandas interaction.

Quick Examples.

Read and write streams.

import tentaclio
contents = "👋 🐙"

with tentaclio.open("ftp://localhost:2021/upload/file.txt", mode="w") as writer:
    writer.write(contents)

# Using boto3 authentication under the hood.
bucket = "s3://my-bucket/octopus/hello.txt"
with tentaclio.open(bucket) as reader:
    print(reader.read())

Copy streams

import tentaclio

tentaclio.copy("/home/constantine/data.csv", "sftp://constantine:tentacl3@sftp.octoenergy.com/uploads/data.csv")

Delete resources

import tentaclio

tentaclio.remove("s3://my-bucket/octopus/the-9th-tentacle.txt")

List resources

import tentaclio

for entry in tentaclio.listdir("s3:://mybucket/path/to/dir"):
    print("Entry", entry)

Authenticated resources.

import os

import tentaclio

print("env ftp credentials", os.getenv("OCTOIO__CONN__OCTOENERGY_FTP"))
# This prints `sftp://constantine:tentacl3@sftp.octoenergy.com/`

# Credentials get automatically injected.

with tentaclio.open("sftp://sftp.octoenergy.com/uploads/data.csv") as reader:
    print(reader.read())

Database connections.

import os

import tentaclio

print("env TENTACLIO__CONN__DB", os.getenv("TENTACLIO__CONN__DB"))

# This prints `postgresql://octopus:tentacle@localhost:5444/example`

# hostname is a wildcard, the credentials get injected.
with tentaclio.db("postgresql://hostname/example") as pg:
    results = pg.query("select * from my_table")

Pandas interaction.

import pandas as pd  # 🐼🐼
import tentaclio  # 🐙

df = pd.DataFrame([[1, 2, 3], [10, 20, 30]], columns=["col_1", "col_2", "col_3"])

bucket = "s3://my-bucket/data/pandas.csv"

with tentaclio.open(bucket, mode="w") as writer:  # supports more pandas readers
    df.to_csv(writer, index=False)

with tentaclio.open(bucket) as reader:
    new_df = pd.read_csv(reader)

Installation

You can get tentaclio using pip

pip install tentaclio

or pipenv

pipenv install tentaclio

Developing.

Clone this repo and install pipenv:

In the Makefile you'll find some useful targets for linting, testing, etc. i.e.:

make test

How to use

This is how to use tentaclio for your daily data ingestion and storing needs.

Streams

In order to open streams to load or store data the universal function is:

import tentaclio

with tentaclio.open("/path/to/my/file") as reader:
    contents = reader.read()

with tentaclio.open("s3://bucket/file", mode='w') as writer:
    writer.write(contents)

Allowed modes are r, w, rb, and wb. You can use t instead of b to indicate text streams, but that's the default.

The supported url protocols are:

• /local/file
• file:///local/file
• s3://bucket/file
• ftp://path/to/file
• sftp://path/to/file
• http://host.com/path/to/resource
• https://host.com/path/to/resource
• postgresql://host/database::table will allow you to write from a csv format into a database with the same column names (note that the table goes after :: :warning:).

You can add the credentials for any of the urls in order to access protected resources.

You can use these readers and writers with pandas functions like:

import pandas as pd
import tentaclio

with tentaclio.open("/path/to/my/file") as reader:
    df = pd.read_csv(reader)

[...]

with tentaclio.open("s3::/path/to/my/file", mode='w') as writer:
    df.to_parquet(writer)

Readers, Writers and their closeable versions can be used anywhere expecting a file-like object; pandas or pickle are examples of such functions.

File system like operations to resources

Listing resources

Some URL schemes allow listing resources in a pythonnic way:

import tentaclio

for entry in tentaclio.listdir("s3:://mybucket/path/to/dir"):
    print("Entry", entry)

Whereas listdir might be convinient we also offer scandir, which returns a list of DirEntrys, and, walk. All functions follow as closely as possible their standard library definitions.

Database access

In order to open db connections you can use tentaclio.db and have instant access to postgres, sqlite, athena and mssql.

import tentaclio

[...]

query = "select 1";
with tentaclio.db(POSTGRES_TEST_URL) as client:
    result =client.query(query)
[...]

The supported db schemes are:

• postgresql://
• sqlite://
• awsathena+rest://
• mssql://
• Any other scheme supported by sqlalchemy.

Automatic credentials injection

1. Configure credentials by using environmental variables prefixed with TENTACLIO__CONN__ (i.e. TENTACLIO__CONN__DATA_FTP=sfpt://real_user:132ldsf@ftp.octoenergy.com).

2. Open a stream:

with tentaclio.open("sftp://ftp.octoenergy.com/file.csv") as reader:
    reader.read()

The credentials get injected into the url.

3. Open a db client:

import tentaclio

with tentaclio.db("postgresql://hostname/my_data_base") as client:
    client.query("select 1")

Note that hostname in the url to be authenticated is a wildcard that will match any hostname. So authenticate("http://hostname/file.txt") will be injected to http://user:pass@octo.co/file.txt if the credential for http://user:pass@octo.co/ exists.

Different components of the URL are set differently:

• Scheme and path will be set from the URL, and null if missing.
• Username, password and hostname will be set from the stored credentials.
• Port will be set from the stored credentials if it exists, otherwise from the URL.
• Query will be set from the URL if it exists, otherwise from the stored credentials (so it can be overriden)

Credentials file

You can also set a credentials file that looks like:

secrets:
    db_1: postgresql://user1:pass1@myhost.com/database_1
    db_2: postgresql://user2:pass2@otherhost.com/database_2
    ftp_server: ftp://fuser:fpass@ftp.myhost.com

And make it accessible to tentaclio by setting the environmental variable TENTACLIO__SECRETS_FILE. The actual name of each url is for traceability and has no effect in the functionality.

Quick note on protocols structural subtyping.

In order to abstract concrete dependencies from the implementation of data related functions (or in any part of the system really) we use typed protocols. This allows a more flexible dependency injection than using subclassing or more complex approches. This idea is heavily inspired by how this exact thing is done in go. Learn more about this principle in our tech blog.