To make it easier for users to upgrade from 1.10 to 2.0 (when it eventually comes out) we should create a single upgrade-check command in 1.10 that checks the following things. We could also have a mode that makes some of these changes in place (with confirmation from user) to automate it.

Rules

Major breaking changes:

• ConnTypeIsNotNullableRule - Not-nullable conn_type column in connection table (done)
• UniqueConnIdRule - Unique conn_id in connection table Add UniqueConnIdRule rule and unittest #11222
• CutomOperatorUsesMetaclassRule - BaseOperator uses metaclass Create CustomOperatorUsesMetaclassRule to ease upgrade to Airflow 2.0 #11038
• UsingSQLFromBaseHookRule - Remove SQL support in base_hook Create UsingSQLFromBaseHookRule to ease upgrade to Airflow 2.0 #11039
• ChainBetwenDAGAndOperatorNotAllowedRule - Assigning task to a DAG using bitwise shift (bit-shift) operators are no longer supported
• AirflowMacroPluginRemovedRule - Removal of airflow.AirflowMacroPlugin class
• NoAdditionalArgsInOperatorsRule - Additional arguments passed to BaseOperator cause an exception Create NoAdditionalArgsInOperatorsRule to ease upgrade to Airflow 2.0 #11042
• MesosExecutorRemovedRule - Removal of Mesos Executor

Config related changes:

• HostnameCallableRule - Unify hostname_callable option in core section Create HostnameCallableRule to ease upgrade to Airflow 2.0 #11044
• StatNameHandlerNotSupportedRule - Drop plugin support for stat_name_handler
• LoggingConfigurationRule - Logging configuration has been moved to new section
• NoGCPServiceAccountKeyInConfigRule - Remove gcp_service_account_keys option in airflow.cfg file
• FernetEnabledRule - Fernet is enabled by default
• KubernetesWorkerAnnotationsRule - Changes to propagating Kubernetes worker annotations
• LegacyUIDeprecatedRule - Deprecate legacy UI in favor of FAB RBAC UI
• TaskHandlersMovedRule - GCSTaskHandler has been moved, WasbTaskHandler has been moved, StackdriverTaskHandler has been moved , S3TaskHandler has been moved, ElasticsearchTaskHandler has been moved, CloudwatchTaskHandler has been moved
• SendGridMovedRule - SendGrid emailer has been moved
• CustomExecutorsRequireFullPathRule - Custom executors is loaded using full import path

Import changes:

• ImportChangesRule - uses a map old_operator_name -> list of possible problems so we can create a single DagBag and scan all used operators and raise information about changes. It should also suggest what providers packages users should use.

How to guide

To implement a new rule we had to create a class that inherits from airflow.upgrade.rules.base_rule.BaseRule. It will be auto-registered and used by airflow upgrade-check command. The custom rule class has to have title, description properties and should implement check method which returns a list of error messages in case of incompatibility.

For example:

Remeber to open the PR against v1-10-test branch.