Add notes about PIP 20.3 breaking Airflow installation

Part of apache#12838

CONTRIBUTING.rst

@@ -1,4 +1,4 @@
- .. Licensed to the Apache Software Foundation (ASF) under one
+.. Licensed to the Apache Software Foundation (ASF) under one
     or more contributor license agreements.  See the NOTICE file
     distributed with this work for additional information
     regarding copyright ownership.  The ASF licenses this file
@@ -532,6 +532,15 @@ than production performance. The production images are not yet officially publis
 Airflow dependencies
 ====================
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 Extras
 ------
 
@@ -666,6 +675,15 @@ as of airflow 1.10.10 and further improved with 1.10.12 (moved to separate orpha
 Pinned constraint files
 =======================
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 By default when you install ``apache-airflow`` package - the dependencies are as open as possible while
 still allowing the apache-airflow package to install. This means that ``apache-airflow`` package might fail to
 install in case a direct or transitive dependency is released that breaks the installation. In such case

IMAGES.rst

@@ -117,6 +117,16 @@ parameter to Breeze:
   ./breeze build-image --python 3.7 --additional-extras=presto \
       --production-image --install-airflow-version=1.10.13
 
+
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 This will build the image using command similar to:
 
 .. code-block:: bash

INSTALL

@@ -28,6 +28,14 @@ java -jar apache-rat.jar -E ./.rat-excludes -d .
 python3 -m venv PATH_TO_YOUR_VENV
 source PATH_TO_YOUR_VENV/bin/activate
 
+NOTE!!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+``--use-deprecated legacy-resolver`` to your pip install command.
+
 # [required] building and installing by pip (preferred)
 pip install .
 

LOCAL_VIRTUALENV.rst

@@ -61,6 +61,16 @@ of required packages.
 Extra Packages
 --------------
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
+
 You can also install extra packages (like ``[ssh]``, etc) via
 ``pip install -e [EXTRA1,EXTRA2 ...]``. However, some of them may
 have additional install and setup requirements for your local system.
@@ -114,6 +124,15 @@ To create and initialize the local virtualenv:
 
 2. Install Python PIP requirements:
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
    .. code-block:: bash
 
     pip install -U -e ".[devel,<OTHER EXTRAS>]" # for example: pip install -U -e ".[devel,google,postgres]"

README.md

@@ -122,6 +122,15 @@ correct Airflow tag/version/branch and python versions in the URL.
 
 1. Installing just Airflow:
 
+NOTE!!!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+`pip upgrade --pip==20.2.4` or, in case you use Pip 20.3, you need to add option
+`--use-deprecated legacy-resolver` to your pip install command.
+
+
 ```bash
 pip install apache-airflow==1.10.13 \
  --constraint "https://raw.githubusercontent.com/apache/airflow/constraints-1.10.13/constraints-3.7.txt"

UPDATING.md

@@ -1668,6 +1668,16 @@ For example:
 If you want to install integration for Microsoft Azure, then instead of `pip install apache-airflow[atlas]`
 you should use `pip install apache-airflow[apache.atlas]`.
 
+
+NOTE!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+`pip upgrade --pip==20.2.4` or, in case you use Pip 20.3, you need to add option
+`--use-deprecated legacy-resolver` to your pip install command.
+
+
 If you want to install integration for Microsoft Azure, then instead of
 
 ```

UPGRADING_TO_2.0.md

@@ -51,6 +51,15 @@ assists users migrating to a new version.
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
+NOTE!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+`pip upgrade --pip==20.2.4` or, in case you use Pip 20.3, you need to add option
+`--use-deprecated legacy-resolver` to your pip install command.
+
+
 ## Step 1: Upgrade to Python 3
 
 Airflow 1.10 will be the last release series to support Python 2. Airflow 2.0.0 will require Python 3.6+.
@@ -102,6 +111,15 @@ The most important step in this transition is also the easiest step to do in pie
 using the [backport providers](./backport-providers.rst) service. In your own time, you can transition to using these backport-providers
 by pip installing the provider via `pypi` and changing the import path.
 
+
+NOTE!!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+`pip upgrade --pip==20.2.4` or, in case you use Pip 20.3, you need to add option
+`--use-deprecated legacy-resolver` to your pip install command.
+
 For example: While historically you might have imported the DockerOperator in this fashion:
 
 ```python

airflow/providers/discord/README.md

@@ -47,6 +47,7 @@ are in `airflow.providers.discord` python package.
 
 ## Installation
 
+
 You can install this package on top of an existing airflow 2.* installation via
 `pip install apache-airflow-providers-discord`
 

dev/provider_packages/PROVIDER_README_TEMPLATE.md.jinja2

@@ -60,6 +60,14 @@ are in `{{FULL_PACKAGE_NAME}}` python package.
 
 ## Installation
 
+NOTE!
+
+On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+`pip upgrade --pip==20.2.4` or, in case you use Pip 20.3, you need to add option
+`--use-deprecated legacy-resolver` to your pip install command.
+
 You can install this package on top of an existing airflow 2.* installation via
 `pip install {{PACKAGE_PIP_NAME}}`
 

docs/apache-airflow/installation.rst

@@ -50,6 +50,15 @@ and python versions in the URL.
 
 1. Installing just Airflow
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 .. code-block:: bash
 
     AIRFLOW_VERSION=1.10.13
@@ -61,6 +70,15 @@ and python versions in the URL.
 
 2. Installing with extras (for example postgres, google)
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 .. code-block:: bash
 
     AIRFLOW_VERSION=1.10.13
@@ -74,11 +92,6 @@ Airflow with such extras, the necessary provider packages are installed automati
 PyPI for those packages). However you can freely upgrade and install provider packages independently from
 the main Airflow installation.
 
-.. note:: Automated installation of Provider packages does not work in Airflow 2.0.0b1 - for this version
-          you have to install provider packages manually. As of Airflow 2.0.0b2 the corresponding
-          provider packages are installed together with the extras.
-
-Read more about it in the :ref:`Provider Packages <installation:provider_packages>` section.
 
 Requirements
 ''''''''''''

docs/apache-airflow/start.rst

@@ -20,6 +20,15 @@
 Quick Start
 -----------
 
+.. note::
+
+   On November 2020, new version of PIP (20.3) has been released with a new, 2020 resolver. This resolver
+   does not yet work with Apache Airflow and might leads to errors in installation - depends on your choice
+   of extras. In order to install Airflow you need to either downgrade pip to version 20.2.4
+   ``pip upgrade --pip==20.2.4`` or, in case you use Pip 20.3, you need to add option
+   ``--use-deprecated legacy-resolver`` to your pip install command.
+
+
 The installation is quick and straightforward.
 
 .. code-block:: bash