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Using Stela

Stela usage is very simple. Just import the env object:

from stela import env

MY_VAR = env.MY_VAR

If you want to get the environment variable programmatically, use the get function:

from stela import env

var = "MY_VAR"
value = env.get(var)

If the variable did not exist, Stela will raise a StelaValueError. You can change this using the raise_on_missing parameter:

from stela import env

var = "THIS_VAR_DOES_NOT_EXIST"
value = env.get(var, raise_on_missing=False)
#> None

If you want to return a default value if the variable does not exist, use the get_or_default function:

from stela import env

var = "THIS_VAR_DOES_NOT_EXIST"
value = env.get_or_default(var, default="default_value")
#> "default_value"

You can also list all environment variables:

from stela import env

all_vars = env.list()
#> ["MY_VAR"]

And you can use the env object to get information about the current environment:

from stela import env

ENV = env.current_environment
DEFAULT_ENV = env.default_environment

When Stela read the data?

Stela is imported once at module level - project settings are load and immediately available:

from stela import env
from flask import Flask

app = Flask(__name__)
app.config.update(
    SECRET_KEY=env.FLASK_SECRET
)


@app.route("/")
def hello():
    return f"Hello, Environment is {env.current_environment}"

Refreshing Stela settings

If you need to reload settings, use the stela.utils.read_env function:

from stela.utils import read_env

def reload_app():
    env = read_env()

Logging data

Stela use the loguru package for logging, using INFO for general messages and DEBUG for key/values retrieved in toml, environment keys, decorators, etc... You can use the logs to debug data during Stela operation.

By default, the log is disabled. You can modify this behavior globally with the following configurations:

[stela]
show_logs = true
log_filtered_value = true

[tool.stela]
show_logs = true
log_filtered_value = true

$ export STELA_SHOW_LOGS=true
$ export STELA_LOG_FILTERED_VALUE=true

Also, you can use decorators for fine-tuning logging per function:

from stela import env
from stela.decorators import stela_enable_logs, stela_disable_logs


@stela_enable_logs
def my_bugged_code():
    return env.MY_API_URL


@stela_disable_logs
def my_sensible_code():
    return env.MY_SECRET_KEY

The log level can be defined using the LOGURU_LOG_LEVEL as per loguru documentation.

For the next step, we will look at how IDEs can autocomplete Stela environment variables.