Enum rusoto_credential::Variable

[−] Show declaration

pub enum Variable<T, E = CredentialsError> {
    Static(T),
    Dynamic(Arc<dyn Fn() -> Result<T, E> + Send + Sync>),
    Fallback(Box<Variable<T, E>>, Box<Variable<T, E>>),
}

[−] Expand description

Variable is an abstraction over parameters to credential providers, allowing to abstract on how (source) and when (time) parameter values are resolved. A lot of credentials providers use external information sources such as environment variables or files to obtain parameter values needed to produce AWS credentials.

Information Sources

• In memory values (static)
• Environment variables (dynamic)
• Files (dynamic)
• …

Resolving Behaviour

• Static variables always resolve to the same value.
• Dynamic variables can resolve to different values over time.

Most prominent examples for dynamic variables are parameters which read their value from environment variables or files.

Variants

Static(T)

[−] Expand description

Static variable always resolving to the same given value.

Dynamic(Arc<dyn Fn() -> Result<T, E> + Send + Sync>)

[−] Expand description

Dynamic variable can resolve to different values over time.

Fallback(Box<Variable<T, E>>, Box<Variable<T, E>>)

[−] Expand description

Fallback try variables in given order returning the value of the first variable that does resolve.

Implementations

impl<T: Clone, E> Variable<T, E>[−]

pub fn with_value<V: Into<T>>(value: V) -> Self[−]

Variable which statically resolves to a provided (in-memory) value.

pub fn resolve(&self) -> Result<T, E>[−]

Resolve the variable’s value.

pub fn or(self, other: Variable<T, E>) -> Self[−]

Combine this Variable with a fallback Variable. Resolving the variable’s value will be done lazily, stopping on the first Variable that successfuly resolves.

Example Usage

let primary: Variable<String> = Variable::from_env_var("AWS_SECRET_ACCESS_KEY");
let fallback = Variable::from_env_var("AWS_SECRET_KEY");
let aws_secret_access_key = primary.or(fallback);

impl<T: 'static, E: 'static> Variable<T, E>[−]

pub fn dynamic(f: impl Fn() -> Result<T, E> + Send + Sync + 'static) -> Self[−]

Variable which dynamically resolves to the value returned from the provided closure. Use this constructor function to create dynamically resolving Variables with custom logic.

impl<T, E> Variable<T, E> where
    T: From<String> + 'static,
    E: From<VarError> + 'static, [−]

pub fn from_env_var<K: AsRef<OsStr>>(key: K) -> Self[−]

Variable which dynamically resolves to the value of a given environment variable.

impl<T, E> Variable<Option<T>, E> where
    T: From<String> + 'static,
    E: From<VarError> + 'static, [−]

pub fn from_env_var_optional<K: AsRef<OsStr>>(key: K) -> Self[−]

Variable which dynamically resolves to the value of a given environment variable.

impl<T, E> Variable<T, E> where
    T: From<String> + 'static,
    E: From<Error> + From<FromUtf8Error> + 'static, [−]

pub fn from_text_file<K: AsRef<Path>>(file: K) -> Self[−]

Variable which dynamically resolves to the value of an UTF-8 encoded text file (removing all leading and trailing whitespaces.

impl<T, E> Variable<T, E> where
    T: From<Vec<u8>> + 'static,
    E: From<Error> + 'static, [−]

pub fn from_binary_file<K: AsRef<Path>>(file: K) -> Self[−]

Variable which dynamically resolves to the value of a binary file.

Trait Implementations

impl<T: Clone, E> Clone for Variable<T, E>[+]

Custom Clone implementation as type parameter E doesn’t have to be cloneable.

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fn clone(&self) -> Self[−]

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)[−]

Performs copy-assignment from source.

impl<T: Debug, E> Debug for Variable<T, E>[+]

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fn fmt(&self, f: &mut Formatter<'_>) -> Result[−]

Formats the value using the given formatter.

impl<E> From<&'_ str> for Variable<String, E>[+]

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fn from(value: &str) -> Self[−]

Performs the conversion.

impl<T, E> From<T> for Variable<T, E> where
    T: Clone, [+]

[+] Show hidden undocumented items

fn from(value: T) -> Self[−]

Performs the conversion.