[AIRFLOW-6330] Show cli help when param blank or typo

[zhongjiajie]

When enter Airflow cli with blank parameter
or typo parameter or wrong parameter will
show Airflow cli help just like enter
Airflow [command] -h command

Make sure you have checked all steps below.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-6330
  • In case you are fixing a typo in the documentation you can prepend your commit with [AIRFLOW-XXX], code changes always need a Jira issue.
  • In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal (AIP).
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Description

• Here are some details about my PR, including screenshots of any UI changes:

When enter Airflow cli with blank parameter
or typo parameter or wrong parameter will
show Airflow cli help just like enter
Airflow [command] -h command

[zhongjiajie]

This patch change cli behavior like below

• Main command or just Airflow

# Only airflow with blank parameter
$ airflow

usage: airflow [-h]
{config,connections,dags,db,flower,kerberos,pools,roles,rotate_fernet_key,scheduler,sync_perm,tasks,users,variables,version,webserver,worker}
                        sub-command help
    config              Show current application configuration
    connections         List/Add/Delete connections
    dags                List and manage DAGs
    db                  Database operations
    flower              Start a Celery Flower
    kerberos            Start a kerberos ticket renewer
    pools               CRUD operations on pools
    roles               Create/List roles
    rotate_fernet_key   Rotate all encrypted connection credentials and
                        variables; see
                        https://airflow.readthedocs.io/en/stable/howto/secure-
                        connections.html#rotating-encryption-keys
    scheduler           Start a scheduler instance
    sync_perm           Update permissions for existing roles and DAGs
    tasks               List and manage tasks
    users               CRUD operations on users
    variables           CRUD operations on variables
    version             Show the version
    webserver           Start a Airflow webserver instance
    worker              Start a Celery worker nodeoptional arguments:
  -h, --help            show this help message and exit

airflow command error: the following arguments are required: subcommand, see help above.


# airflow [subcommands] with blank parameter
$ airflow connections

usage: airflow connections [-h] {list,add,delete} ...positional arguments:
  {list,add,delete}
    list             List connections
    add              Add a connection
    delete           Delete a connectionoptional arguments:
  -h, --help         show this help message and exit

airflow connections command error: the following arguments are required: subcommand, see help above.

• typo or wrong parameter

$ airflow connections docker

usage: airflow connections [-h] {list,add,delete} ...positional arguments:
  {list,add,delete}
    list             List connections
    add              Add a connection
    delete           Delete a connectionoptional arguments:
  -h, --help         show this help message and exit

airflow connections command error: argument subcommand: invalid choice: 'docker' (choose from 'list', 'add', 'delete'), see help above.

[kaxil]

Travis is sad:

airflow/bin/cli.py:1002:8: C0111: Missing class docstring (missing-docstring)

[codecov-io]

Codecov Report

Merging #6883 into master will decrease coverage by 0.28%.
The diff coverage is 60%.

@@            Coverage Diff             @@
##           master    #6883      +/-   ##
==========================================
- Coverage   84.62%   84.33%   -0.29%     
==========================================
  Files         679      679              
  Lines       38497    38501       +4     
==========================================
- Hits        32578    32470     -108     
- Misses       5919     6031     +112

Impacted Files	Coverage Δ
airflow/bin/cli.py	93.42% <60%> (-2.42%)	⬇️
airflow/kubernetes/volume_mount.py	44.44% <0%> (-55.56%)	⬇️
airflow/kubernetes/volume.py	52.94% <0%> (-47.06%)	⬇️
airflow/kubernetes/pod_launcher.py	45.25% <0%> (-46.72%)	⬇️
airflow/kubernetes/refresh_config.py	50.98% <0%> (-23.53%)	⬇️
...rflow/contrib/operators/kubernetes_pod_operator.py	78.75% <0%> (-20%)	⬇️

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[zhongjiajie]

Finally CI green, PTAL @kaxil @mik-laj @potiuk

[potiuk]

Nice one @zhongjiajie !