monasca-agent/docs/DeveloperDocs/agent_internals.md

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**Table of Contents**

- [Modify_Config](#modify_config)
  - [Examples](#examples)
      - [Adding a new instance](#adding-a-new-instance)
      - [Changing the current instance](#changing-the-current-instance)
- [Connector](#connector)
  - [Kubernetes Connector](#kubernetes-connector)
- [License](#license)

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# Modify_Config
Modify_config is a function in [monasca_setup/main.py](monasca_setup/main.py).
It compares existing and detected configurations for each check plugin and
writes out the plugin configurations if there are changes.

## Examples
There are two examples shown here using http_check to:
* add a new instance
* detect endpoint change on an existing http_check instance

#### Adding a new instance
old_config:

```
{'init_config': None,
 'instances': [{'built_by': 'HttpCheck',
                'name': 'logging',
                'url': 'http://127.0.0.1:9200',
                'use_keystone': False,
                'match_pattern': '.*VERSION.*',
                'collect_response_time': True,
                'timeout': '10',
                'dimensions': {'service': 'logging'}}]
}
```

monasca-setup arguments:

    $ monasca-setup -d 'HttpCheck' -a 'url=http://192.168.10.6:8070
      match_pattern=.*OK.* name=monasca dimensions=service:monitoring'

input_config generated from monasca-setup:

```
{'http_check':
    {'instances': [{'built_by': 'HttpCheck',
                    'name': 'monasca',
                    'url': 'http://192.168.10.6:8070',
                    'use_keystone': False,
                    'match_pattern': '.*OK.*',
                    'collect_response_time': True,
                    'timeout': '10',
                    'dimensions': {'service': 'monitoring'}
                    }]
    'init_config': None
    }
}
```

output_config from modify_config:

```
{'init_config': None,
 'instances': [{'built_by': 'HttpCheck',
                'name': 'logging',
                'url': 'http://127.0.0.1:9200',
                'use_keystone': False,
                'match_pattern': '.*VERSION.*',
                'collect_response_time': True,
                'timeout': '10',
                'dimensions': {'service': 'logging'}},
               {'built_by': 'HttpCheck',
                'name': 'monasca',
                'url': 'http://192.168.10.6:8070',
                'use_keystone': False,
                'match_pattern': '.*OK.*',
                'collect_response_time': True,
                'timeout': '10',
                'dimensions': {'service': 'monitoring'}}]
}
```

#### Changing the current instance
old_config:

```
{'init_config': None,
 'instances': [{'built_by': 'HttpCheck',
                'name': 'logging',
                'url': 'http://192.168.10.6:8070',
                'use_keystone': False,
                'match_pattern': '.*VERSION.*',
                'collect_response_time': True,
                'timeout': '10',
                'dimensions': {'service': 'logging'}}]
}
```

monasca-setup arguments:

    $ monasca-setup -d 'HttpCheck' -a 'url=https://192.168.10.6:8070
      match_pattern=.*VERSION.* dimensions=service:logging'

input_config generated from monasca-setup:

```
{'http_check':
   {'instances': [{'built_by': 'HttpCheck',
                    'name': 'https://192.168.10.6:8070',
                    'url': 'https://192.168.10.6:8070',
                    'use_keystone': False,
                    'match_pattern': '.*VERSION.*',
                    'collect_response_time': True,
                    'dimensions': {'service': 'logging'}
                    }]
    'init_config': None
   }
}
```

output_config from modify_config:

```
{'init_config': None,
 'instances': [{'built_by': 'HttpCheck',
                'name': 'https://192.168.10.6:8070',
                'url': 'https://192.168.10.6:8070',
                'use_keystone': False,
                'match_pattern': '.*VERSION.*',
                'collect_response_time': True,
                'dimensions': {'service': 'logging'}
                }]
}
```

# Connector
## Kubernetes Connector
Kubernetes Connector is a class within [monasca-collector utils](monasca_agent/collector/checks/utils.py)
that is used for connecting to the Kubernetes API from within a container that is running in a k8 cluster.

When a container is brought up in Kubernetes by default there are environmental variables passed in that include needed
configurations to connect to the API. Also, the cacert and token that is tied to the serviceaccount the container is
under is mounted to the container file system. This class processes both and allows requests to the Kubernetes API.

# License
(C) Copyright 2016,2017 Hewlett Packard Enterprise Development LP