add execution contexts

[leo-schick]

In WIP feature discussion in #68

[leo-schick]

Current status

the BashExecutionContext and SshBashExecutionContext works, but logging should be optimized

Sample app

local_config.py

from mara_pipelines.contexts.bash import BashExecutionContext, SshBashExecutionContext
patch(mara_pipelines.config.execution_contexts)(lambda: {
    'bash': BashExecutionContext(),
    'srv-mara-2': SshBashExecutionContext(
        host='srv-mara-2'
    ),
})

test.py

from mara_pipelines.pipelines import Pipeline, Task
from mara_pipelines.commands.bash import RunBash

test_pipeline = Pipeline(
    id='test',
    description="",
    context='srv-mara-2')

test_pipeline.add(
    Task(id='ls',
         description="",
         commands=[
             RunBash('ls -l')
         ]))

test_pipeline.add(
    Task(id='ls2',
         description="",
         commands=[
             RunBash('ls -l .venv')
         ],
         context='bash'),
    upstreams=['ls'])

Live execution output

Output after execution:

Open tasks

• 🐛 the log message exit execution context '{context_alias}' is not saved in the database log
• 🚀 use better logging, don't use print, see mara_pipelines.execution.py
• 🚀 add logging events for enter/exit of a execution context
• 🚀 start/stop docker container when not started when calling method __enter__
• 🚀 show somehwere in the nodes page which execution context is used

[leo-schick]

Currently known issue: when a execution context is used which is not defined in the configuration the pipeline execution does not throw any message and just hangs