Install dotenv in a directory as shown above. Create an dotenv-example. As you can see the value was loaded and defined using dotenv. Change your dotenv-example. The script should print that the current value for FOO is undefined. Now execute it with the appropriate flag to require dotenv :.
The result is that FOO is now set to bar since the. If you want to learn more about dotenv make sure to check out its documentation. Now dotenv is great but there was one particular thing that bothered me personally during my development process. As a result of these frustrations, I decided to write my own module based on dotenv to fix this problem and make loading environment variables more convenient things.
The result is node-env-run or nodenv. You can install it globally but I recommend to only use it for development purposes and locally to the project. Install it by running:. First try running it using node :. This executed code should output The value for FOO is: undefined. Now try using node-env-run by running:. The result should be The value for FOO is: bar since it loaded the. To see it in action first run the following command:.
The command-line output should say The value for FOO is: foo. If we now enable force mode we can override existing values:. If you want to use this tool regularly, I recommend that you wrap it into an npm script. By adding it in the package.
If you want to learn more about node-env-run make sure to check out its documentation. For example if you want to use node-env-run when you are in a development environment but node when you are in production mode. A tool that makes this very easy is if-env. This script will now execute npm run start:prod and subsequently node.
You can do this technique with any other environment variable as well. If you want to learn more about if-env make sure to check out its documentation.
One strategy that helped me a lot is using the DEBUG environment variable to receive more verbose logs for a bunch of modules. If you for example take a basic express server like this:. Afterwards you can log to that namespace. If someone wants to see the output all they have to do is enable the namespace in the DEBUG variable. If you would want everything from the express router, all you have to do is set DEBUG with the appropriate wildcard:. They can be defined in most cloud-provider Platform as a Service PaaS offerings, and are a common method for configuring platforms, like Docker.
However, it is sometimes convenient to define application settings in a local configuration file instead. Platforms like Heroku, for instance, use. To run the application locally, ensure Node. Alternatively, you can run the application in CodeSandBox. Click the link to open the GitHub source code in a new sandbox to build, run, and expose via a random URL.
The following code shows a simple Node. We can attempt to parse an integer value from the PORT environment variable, or default to Port if the environment variable is not defined or contains something other than an integer:.
Here, we return the name defined above:. Why go through the trouble of overriding values, like port numbers, with environment variables in the first place? These values can already pass in as command line arguments or load from JSON or YAML configuration files, providing more flexibility than environment variables exposing a simple name and value pairs. However, because reading values from environment variables are often required by PaaS solutions, the PORT environment variable became a de facto standard for defining which port an application listens to.
The twelve-factor app stores config in environment variables often shortened to env vars or env. Env vars are easy to change between deploys without changing any code; unlike config files, there is little chance of them being checked into the code repo accidentally; and unlike custom config files, or other config mechanisms such as Java System Properties, they are a language- and OS-agnostic standard.
By configuring our application via environment variables, we can be sure our code is easy to deploy and customize across a wide range of platforms. A Node. The dotenv library will never modify any environment variables that have already been set. If a variable has already been set in your environment, and the variable in the.
Thanks for reading and if you have any questions , use the comment function or send me a message mariokandut. If you want to know more about Node , have a look at these Node Tutorials. November 09, Learn how to use streams to extract, transform and load data. August 11, Learn what pipeline does, and how to connect streams using pipeline. August 10, If a stream error is not handled, it can crash your application. How to use streams to ETL data?
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