# Vyper [](https://travis-ci.com/alexferl/vyper) [](https://codecov.io/gh/alexferl/vyper)
Python configuration with (more) fangs! Python port of the very awesome [Viper](https://github.com/spf13/viper) for Go.
## PyPI name change
The package changed name on pypi from `vyper` to `vyper-config` on August 20th 2018.
The `vyper` name is now used by the following [project](https://github.com/ethereum/vyper).
The `vyper-config` package is available on [PyPI](https://pypi.org/project/vyper-config/).
## What is Vyper?
Vyper is a complete configuration solution for Python applications including 12 factor apps. It is designed
to work within an application, and can handle all types of configuration needs and formats. It supports:
* setting defaults
* reading from JSON, TOML, and YAML config files
* live watching and re-reading of config files (optional)
* reading from environment variables
* reading from remote config systems (etcd, Consul or ZooKeeper)
* live watching and re-reading of remote config files (optional)
* reading from command line arguments
* reading from buffer
* setting explicit values
Vyper can be thought of as a registry for all of your applications
configuration needs.
## Why Vyper?
When building a modern application, you don’t want to worry about
configuration file formats; you want to focus on building awesome software.
Vyper is here to help with that.
Vyper does the following for you:
1. Find, load, and unmarshall a configuration file in JSON, TOML, or YAML format.
2. Provide a mechanism to set default values for your different
configuration options.
3. Provide a mechanism to set override values for options specified through
command line arguments.
4. Provide an alias system to easily rename parameters without breaking existing
code.
5. Make it easy to tell the difference between when a user has provided a
command line or config file which is the same as the default.
Vyper uses the following precedence order. Each item takes precedence over the
item below it:
* explicit call to set
* argument
* environment variable
* config
* key/value store
* default
Vyper configuration keys are case insensitive.
## Putting Values into Vyper
### Establishing Defaults
A good configuration system will support default values. A default value is not
required for a key, but it's useful in the event that a key hasn't been set via
config file, environment variable, remote configuration or argument.
Examples:
```python
v.set_default('ContentDir', 'content')
v.set_default('LayoutDir', 'layouts')
v.set_default('Taxonomies', {'tag': 'tags', 'category': 'categories'})
```
### Reading Config Files
Vyper requires minimal configuration so it knows where to look for config files.
Vyper supports JSON, TOML and YAML files. Vyper can search multiple paths, but
currently a single Vyper instance only supports a single configuration file.
Vyper does not default to any configuration search paths leaving defaults decision
to an application.
Here is an example of how to use Vyper to search for and read a configuration file.
None of the specific paths are required, but at least one path should be provided
where a configuration file is expected.
```python
v.set_config_name('config') # name of config file (without extension)
v.add_config_path('/etc/appname/') # path to look for the config file in
v.add_config_path('$HOME/.appname') # call multiple times to add many search paths
v.add_config_path('.') # optionally look for config in the working directory
v.read_in_config() # Find and read the config file
```
### Watching and re-reading config files
Vyper supports the ability to have your application live read a config file while running.
Gone are the days of needing to restart a server to have a config take effect,
vyper powered applications can read an update to a config file while running and
not miss a beat.
Simply tell the Vyper instance to watch_config().
Optionally you can provide a function for Vyper to run each time a change occurs.
**Make sure you add all of the config_paths prior to calling `watch_config()`**
```python
v.watch_config()
def f():
print('Config file changed')
v.on_config_change(f)
```
### Reading Config from buffer
Vyper pre-defines many configuration sources such as files, environment
variables, arguments, and remote K/V store, but you are not bound to them. You can
also implement your own required configuration source and feed it to Vyper.
```python
v.set_config_type('yaml') # or v.set_config_type('YAML')
# any approach to require this configuration into your program.
yaml_example = '''
Hacker: true
name: steve
hobbies:
- skateboarding
- snowboarding
- go
clothing:
jacket: leather
trousers: denim
age: 35
eyes : brown
beard: true
'''
v.read_config(yaml_example)
v.get('name') # this would be 'steve'
```
### Setting Overrides
These could be from a command line argument, or from your own application logic.
```python
v.set('Verbose', True)
v.set('LogFile', log_file)
```
### Registering and Using Aliases
Aliases permit a single value to be referenced by multiple keys
```python
v.register_alias('loud', 'Verbose')
v.set('verbose', True) # same result as next line
v.set('loud', True) # same result as prior line
v.get_bool('loud') # True
v.get_bool('verbose') # True
```
### Working with Environment Variables
Vyper has full support for environment variables. This enables 12 factor
applications out of the box. There are four methods that exist to aid working
with ENV:
* `automatic_env()`
* `bind_env(string)`
* `set_env_prefix(string)`
* `set_env_replacer(string)`
_When working with ENV variables, it’s important to recognize that Vyper
treats ENV variables as case sensitive._
Vyper provides a mechanism to try to ensure that ENV variables are unique. By
using `set_env_prefix()`, you can tell Vyper to use add a prefix while reading from
the environment variables. Both `bind_env()` and `automatic_env()` will use this
prefix.
`bind_env()` takes one or two parameters. The first parameter is the key name, the
second is the name of the environment variable. The name of the environment
variable is case sensitive. If the ENV variable name is not provided, then
Vyper will automatically assume that the key name matches the ENV variable name,
but the ENV variable is IN ALL CAPS. When you explicitly provide the ENV
variable name, it **does not** automatically add the prefix.
One important thing to recognize when working with ENV variables is that the
value will be read each time it is accessed. Vyper does not fix the value when
the `bind_env()` is called.
`automatic_env()` is a powerful helper especially when combined with
`set_env_prefix()`. When called, Vyper will check for an environment variable any
time a `v.get()` request is made. It will apply the following rules. It will
check for a environment variable with a name matching the key uppercased and
prefixed with the `env_prefix()` if set.
`set_env_replacer()` allows you to use a `str` object to rewrite Env
keys to an extent. This is useful if you want to use `-` or something in your
`get()` calls, but want your environmental variables to use `_` delimiters. An
example of using it can be found in `tests/test_vyper.py`.
#### Env example
```python
v.set_env_prefix('spf') # will be uppercased automatically
v.bind_env('id')
os.environ['SPF_ID'] = '13' # typically done outside of the app
id = v.get('id') # 13
```
### Working with command line arguments
Vyper has the ability to bind to command line arguments.
Specifically, Vyper supports `argparse`.
See [doc](docs.python.org/3.7/library/argparse.html#argparse.ArgumentParser)
for more details.
The values are set when the binding method is called.
As it deals with command line arguments, the `bind_args()` method needs to be called passing
an instance of argparse.ArgumentParser(). The method also sets defaults based on what you pass
via `add_argument()` `default` parameter.
Note: If you don't specify a default, the values will be set to `None`.
```python
p = argparse.ArgumentParser(description="Application settings")
p.add_argument('--app-name', type=str, help='Application and process name')
p.add_argument('--env', type=str, choices=['dev', 'pre-prod', 'prod'], help='Application env')
p.add_argument('--port', type=int, default=5000, help='Application port')
p.add_argument('--password', type=str, help='Application password')
v.bind_args(p)
# "your_app.py", "--app-name=cmd-app", "--env=prod"
app_name = v.get('app_name') # 'cmd-app'
env = v.get('env') # 'prod'
port = v.get('port') # 5000
password = v.get('password') # `None`
```
## Getting Values From Vyper
In Vyper, there are a few ways to get a value depending on the value's type.
The following functions and methods exist:
* `get(key)`
* `get_bool(key) : bool`
* `get_float(key) : float`
* `get_int(key) : int`
* `get_string(key) : str`
* `is_set(key) : bool`
One important thing to recognize is that each get function will return a zero
value if it’s not found. To check if a given key exists, the `is_set()` method
has been provided.
Example:
```python
v.get_string('logfile') # case-insensitive Setting & Getting
if v.get_bool('verbose'):
print('verbose enabled')
```
### Accessing nested keys
The accessor methods also accept formatted paths to deeply nested keys. For
example, if the following JSON file is loaded:
```json
{
"host": {
"address": "localhost",
"port": 5799
},
"datastore": {
"metric": {
"host": "127.0.0.1",
"port": 3099
},
"warehouse": {
"host": "198.0.0.1",
"port": 2112
}
}
}
```
Vyper can access a nested field by passing a `.` delimited path of keys:
```python
v.get_string('datastore.metric.host') # returns '127.0.0.1'
```
This obeys the precedence rules established above; the search for the root key
(in this example, `datastore`) will cascade through the remaining configuration
registries until found. The search for the sub-keys (`metric` and `host`),
however, will not.
For example, if the `metric` key was not defined in the configuration loaded
from file, but was defined in the defaults, Vyper would return the zero value.
On the other hand, if the primary key was not defined, Vyper would go through
the remaining registries looking for it.
Lastly, if there exists a key that matches the delimited key path, its value
will be returned instead. E.g.
```json
{
"datastore.metric.host": "0.0.0.0",
"host": {
"address": "localhost",
"port": 5799
},
"datastore": {
"metric": {
"host": "127.0.0.1",
"port": 3099
},
"warehouse": {
"host": "198.0.0.1",
"port": 2112
}
}
}
v.get_string('datastore.metric.host') # returns '0.0.0.0'
```
## Vyper or Vypers?
Vyper comes ready to use out of the box. There is no configuration or
initialization needed to begin using Vyper. Since most applications will want
to use a single central repository for their configuration, the vyper package
provides this. It is similar to a singleton.
In all of the examples above, they demonstrate using vyper in it's singleton
style approach.
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"description": "# Vyper [](https://travis-ci.com/alexferl/vyper) [](https://codecov.io/gh/alexferl/vyper)\n\nPython configuration with (more) fangs! Python port of the very awesome [Viper](https://github.com/spf13/viper) for Go.\n\n## PyPI name change\nThe package changed name on pypi from `vyper` to `vyper-config` on August 20th 2018.\nThe `vyper` name is now used by the following [project](https://github.com/ethereum/vyper).\nThe `vyper-config` package is available on [PyPI](https://pypi.org/project/vyper-config/).\n\n## What is Vyper?\n\nVyper is a complete configuration solution for Python applications including 12 factor apps. It is designed\nto work within an application, and can handle all types of configuration needs and formats. It supports:\n\n* setting defaults\n* reading from JSON, TOML, and YAML config files\n* live watching and re-reading of config files (optional)\n* reading from environment variables\n* reading from remote config systems (etcd, Consul or ZooKeeper)\n* live watching and re-reading of remote config files (optional)\n* reading from command line arguments\n* reading from buffer\n* setting explicit values\n\nVyper can be thought of as a registry for all of your applications\nconfiguration needs.\n\n## Why Vyper?\n\nWhen building a modern application, you don\u2019t want to worry about\nconfiguration file formats; you want to focus on building awesome software.\nVyper is here to help with that.\n\nVyper does the following for you:\n\n1. Find, load, and unmarshall a configuration file in JSON, TOML, or YAML format.\n2. Provide a mechanism to set default values for your different\n configuration options.\n3. Provide a mechanism to set override values for options specified through\n command line arguments.\n4. Provide an alias system to easily rename parameters without breaking existing\n code.\n5. Make it easy to tell the difference between when a user has provided a\n command line or config file which is the same as the default.\n\nVyper uses the following precedence order. Each item takes precedence over the\nitem below it:\n\n * explicit call to set\n * argument\n * environment variable\n * config\n * key/value store\n * default\n\nVyper configuration keys are case insensitive.\n\n## Putting Values into Vyper\n\n### Establishing Defaults\n\nA good configuration system will support default values. A default value is not\nrequired for a key, but it's useful in the event that a key hasn't been set via\nconfig file, environment variable, remote configuration or argument.\n\nExamples:\n\n```python\nv.set_default('ContentDir', 'content')\nv.set_default('LayoutDir', 'layouts')\nv.set_default('Taxonomies', {'tag': 'tags', 'category': 'categories'})\n```\n\n### Reading Config Files\n\nVyper requires minimal configuration so it knows where to look for config files.\nVyper supports JSON, TOML and YAML files. Vyper can search multiple paths, but\ncurrently a single Vyper instance only supports a single configuration file.\nVyper does not default to any configuration search paths leaving defaults decision\nto an application.\n\nHere is an example of how to use Vyper to search for and read a configuration file.\nNone of the specific paths are required, but at least one path should be provided\nwhere a configuration file is expected.\n\n```python\nv.set_config_name('config') # name of config file (without extension)\nv.add_config_path('/etc/appname/') # path to look for the config file in\nv.add_config_path('$HOME/.appname') # call multiple times to add many search paths\nv.add_config_path('.') # optionally look for config in the working directory\nv.read_in_config() # Find and read the config file\n```\n\n### Watching and re-reading config files\n\nVyper supports the ability to have your application live read a config file while running.\n\nGone are the days of needing to restart a server to have a config take effect,\nvyper powered applications can read an update to a config file while running and\nnot miss a beat.\n\nSimply tell the Vyper instance to watch_config().\nOptionally you can provide a function for Vyper to run each time a change occurs.\n\n**Make sure you add all of the config_paths prior to calling `watch_config()`**\n\n```python\nv.watch_config()\ndef f():\n print('Config file changed')\nv.on_config_change(f)\n```\n\n### Reading Config from buffer\n\nVyper pre-defines many configuration sources such as files, environment\nvariables, arguments, and remote K/V store, but you are not bound to them. You can\nalso implement your own required configuration source and feed it to Vyper.\n\n```python\nv.set_config_type('yaml') # or v.set_config_type('YAML')\n\n# any approach to require this configuration into your program.\nyaml_example = '''\nHacker: true\nname: steve\nhobbies:\n- skateboarding\n- snowboarding\n- go\nclothing:\n jacket: leather\n trousers: denim\nage: 35\neyes : brown\nbeard: true\n'''\n\nv.read_config(yaml_example)\n\nv.get('name') # this would be 'steve'\n```\n\n### Setting Overrides\n\nThese could be from a command line argument, or from your own application logic.\n\n```python\nv.set('Verbose', True)\nv.set('LogFile', log_file)\n```\n\n### Registering and Using Aliases\n\nAliases permit a single value to be referenced by multiple keys\n\n```python\nv.register_alias('loud', 'Verbose')\n\nv.set('verbose', True) # same result as next line\nv.set('loud', True) # same result as prior line\n\nv.get_bool('loud') # True\nv.get_bool('verbose') # True\n```\n\n### Working with Environment Variables\n\nVyper has full support for environment variables. This enables 12 factor\napplications out of the box. There are four methods that exist to aid working\nwith ENV:\n\n * `automatic_env()`\n * `bind_env(string)`\n * `set_env_prefix(string)`\n * `set_env_replacer(string)`\n\n_When working with ENV variables, it\u2019s important to recognize that Vyper\ntreats ENV variables as case sensitive._\n\nVyper provides a mechanism to try to ensure that ENV variables are unique. By\nusing `set_env_prefix()`, you can tell Vyper to use add a prefix while reading from\nthe environment variables. Both `bind_env()` and `automatic_env()` will use this\nprefix.\n\n`bind_env()` takes one or two parameters. The first parameter is the key name, the\nsecond is the name of the environment variable. The name of the environment\nvariable is case sensitive. If the ENV variable name is not provided, then\nVyper will automatically assume that the key name matches the ENV variable name,\nbut the ENV variable is IN ALL CAPS. When you explicitly provide the ENV\nvariable name, it **does not** automatically add the prefix.\n\nOne important thing to recognize when working with ENV variables is that the\nvalue will be read each time it is accessed. Vyper does not fix the value when\nthe `bind_env()` is called.\n\n`automatic_env()` is a powerful helper especially when combined with\n`set_env_prefix()`. When called, Vyper will check for an environment variable any\ntime a `v.get()` request is made. It will apply the following rules. It will\ncheck for a environment variable with a name matching the key uppercased and\nprefixed with the `env_prefix()` if set.\n\n`set_env_replacer()` allows you to use a `str` object to rewrite Env\nkeys to an extent. This is useful if you want to use `-` or something in your\n`get()` calls, but want your environmental variables to use `_` delimiters. An\nexample of using it can be found in `tests/test_vyper.py`.\n\n#### Env example\n\n```python\nv.set_env_prefix('spf') # will be uppercased automatically\nv.bind_env('id')\n\nos.environ['SPF_ID'] = '13' # typically done outside of the app\n\nid = v.get('id') # 13\n```\n\n### Working with command line arguments\n\nVyper has the ability to bind to command line arguments.\nSpecifically, Vyper supports `argparse`.\nSee [doc](docs.python.org/3.7/library/argparse.html#argparse.ArgumentParser)\nfor more details.\n\nThe values are set when the binding method is called.\n\nAs it deals with command line arguments, the `bind_args()` method needs to be called passing\nan instance of argparse.ArgumentParser(). The method also sets defaults based on what you pass\nvia `add_argument()` `default` parameter.\n\nNote: If you don't specify a default, the values will be set to `None`.\n\n```python\np = argparse.ArgumentParser(description=\"Application settings\")\np.add_argument('--app-name', type=str, help='Application and process name')\np.add_argument('--env', type=str, choices=['dev', 'pre-prod', 'prod'], help='Application env')\np.add_argument('--port', type=int, default=5000, help='Application port')\np.add_argument('--password', type=str, help='Application password')\nv.bind_args(p)\n\n# \"your_app.py\", \"--app-name=cmd-app\", \"--env=prod\"\n\napp_name = v.get('app_name') # 'cmd-app'\nenv = v.get('env') # 'prod'\nport = v.get('port') # 5000\npassword = v.get('password') # `None`\n```\n\n## Getting Values From Vyper\n\nIn Vyper, there are a few ways to get a value depending on the value's type.\nThe following functions and methods exist:\n\n * `get(key)`\n * `get_bool(key) : bool`\n * `get_float(key) : float`\n * `get_int(key) : int`\n * `get_string(key) : str`\n * `is_set(key) : bool`\n\nOne important thing to recognize is that each get function will return a zero\nvalue if it\u2019s not found. To check if a given key exists, the `is_set()` method\nhas been provided.\n\nExample:\n```python\nv.get_string('logfile') # case-insensitive Setting & Getting\nif v.get_bool('verbose'):\n print('verbose enabled')\n```\n### Accessing nested keys\n\nThe accessor methods also accept formatted paths to deeply nested keys. For\nexample, if the following JSON file is loaded:\n\n```json\n{\n \"host\": {\n \"address\": \"localhost\",\n \"port\": 5799\n },\n \"datastore\": {\n \"metric\": {\n \"host\": \"127.0.0.1\",\n \"port\": 3099\n },\n \"warehouse\": {\n \"host\": \"198.0.0.1\",\n \"port\": 2112\n }\n }\n}\n\n```\n\nVyper can access a nested field by passing a `.` delimited path of keys:\n\n```python\nv.get_string('datastore.metric.host') # returns '127.0.0.1'\n```\n\nThis obeys the precedence rules established above; the search for the root key\n(in this example, `datastore`) will cascade through the remaining configuration\nregistries until found. The search for the sub-keys (`metric` and `host`),\nhowever, will not.\n\nFor example, if the `metric` key was not defined in the configuration loaded\nfrom file, but was defined in the defaults, Vyper would return the zero value.\n\nOn the other hand, if the primary key was not defined, Vyper would go through\nthe remaining registries looking for it.\n\nLastly, if there exists a key that matches the delimited key path, its value\nwill be returned instead. E.g.\n\n```json\n{\n \"datastore.metric.host\": \"0.0.0.0\",\n \"host\": {\n \"address\": \"localhost\",\n \"port\": 5799\n },\n \"datastore\": {\n \"metric\": {\n \"host\": \"127.0.0.1\",\n \"port\": 3099\n },\n \"warehouse\": {\n \"host\": \"198.0.0.1\",\n \"port\": 2112\n }\n }\n}\n\nv.get_string('datastore.metric.host') # returns '0.0.0.0'\n```\n\n## Vyper or Vypers?\n\nVyper comes ready to use out of the box. There is no configuration or\ninitialization needed to begin using Vyper. Since most applications will want\nto use a single central repository for their configuration, the vyper package\nprovides this. It is similar to a singleton.\n\nIn all of the examples above, they demonstrate using vyper in it's singleton\nstyle approach.\n",
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