68 lines
2.3 KiB
Markdown
68 lines
2.3 KiB
Markdown
# Envhead
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Envhead is a crate that creates environment variable names using a static prefix.
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## Setup
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First, you should define the prefix by setting the `ENV_HEAD_PREFIX` environment variable to the desired value. When the `ENV_HEAD_PREFIX` variable is not defined, `ENV` is used as the default prefix. In the following examples, we will use `MY_APP` as the prefix.
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In case you are working with macOS or Linux, you might use Bash like this:
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```bash
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ENV_HEAD_PREFIX=MY_APP cargo build
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```
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Using an IDE from JetBrains like [RustRover](https://www.jetbrains.com/rust/), you can set the environment variable in the [run configuration](https://www.jetbrains.com/help/rust/cargo-run-debug-configuration.html) and for your [integrated terminal](https://www.jetbrains.com/help/clion/settings-tools-terminal.html).
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Do you use a CI/CD pipeline? You can set the environment variable in your pipeline configuration. Do you build your application in a Docker container? You can set the environment variable in your Dockerfile as well.
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**Please notice:** This setup procedure is required just for the development environment. Your compiled program(s) will not depend on the `ENV_HEAD_PREFIX` environment variable.
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## Usage
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Now, in your code, you can use the `envhead!` macro to create environment variable names.
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```rust
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use envhead::envhead;
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fn main() {
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let env_var = envhead!("server_port");
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// Prints "MY_APP_SERVER_PORT":
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println!("{}", env_var);
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}
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```
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You might find it useful to use `envhead` together with `clap` to create environment variable names for your command line arguments:
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```rust
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use clap::Args;
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use envhead::envhead;
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#[derive(Debug, Args)]
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pub struct ServerArgs {
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#[arg(
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short = 'p', long,
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required = false,
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value_name = "port",
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value_hint = clap::ValueHint::Other,
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help = "The server's port.",
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default_value_t = 8000,
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env = envhead!("server_port"),
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)]
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pub port: u16,
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#[arg(
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long,
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required = true,
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value_name = "SECRET_TOKEN",
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value_hint = clap::ValueHint::Other,
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help = "The secret token to authenticate the client.",
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env = envhead!("server_secret_token"),
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)]
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pub secret_token: Option<String>,
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}
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```
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# Changelog
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### Version 1.0.0
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- Initial release |