Struct FileTokenProvider 

pub struct FileTokenProvider { /* private fields */ }

Reads a bearer token from a file, caching the result for a configurable TTL.

Designed for Kubernetes projected service account tokens and Vault agent sidecars, where the platform writes a short-lived JWT to a known path and rotates it in place before expiry. The cache avoids a filesystem syscall on every call while still picking up rotated tokens within one TTL period.

Token lifecycle

• On the first get_token() call (or after the cache TTL expires), the file is read from disk and the result is cached.
• Subsequent calls within the TTL return the cached string with no I/O.
• The kubelet guarantees the file is rotated before the old token expires, so there is no window where the cached token is expired but the file has not yet been updated.

Construction

use rust_auth_lib::{ConfigError, FileTokenProvider};
use std::time::Duration;

// From an explicit path (30 s default TTL):
let provider = FileTokenProvider::new("/var/run/secrets/tokens/my-token");

// From an explicit path with a custom TTL:
let provider = FileTokenProvider::with_ttl(
    "/var/run/secrets/tokens/my-token",
    Duration::from_secs(60),
);

// From environment variables:
let provider_result: Result<FileTokenProvider, ConfigError> =
    FileTokenProvider::from_env();

Cloning

FileTokenProvider wraps an Arc internally. Cloning is cheap and all clones share the same cache.

Implementations

impl FileTokenProvider

pub fn new(path: impl Into<PathBuf>) -> FileTokenProvider

Create a provider that reads from path with a 30-second cache TTL.

pub fn with_ttl( path: impl Into<PathBuf>, cache_ttl: Duration, ) -> FileTokenProvider

Create a provider that reads from path with an explicit cache TTL.

pub fn from_env() -> Result<FileTokenProvider, ConfigError>

Construct from environment variables.

Reads:

• SERVICE_TOKEN_FILE (required) — path to the token file
• SERVICE_TOKEN_CACHE_TTL_SECS (optional, default: 30) — cache TTL in seconds. If the variable is set but cannot be parsed as a u64, it silently falls back to 30.

Trait Implementations

impl Clone for FileTokenProvider

fn clone(&self) -> FileTokenProvider

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl TokenProvider for FileTokenProvider

fn get_token(&self) -> Result<String, TokenError>

Return the current bearer token string.