Current File : /home/opti/workflow/node_modules/aws-sdk/lib/credentials/credential_provider_chain.js
var AWS = require('../core');
/**
* Creates a credential provider chain that searches for AWS credentials
* in a list of credential providers specified by the {providers} property.
*
* By default, the chain will use the {defaultProviders} to resolve credentials.
* These providers will look in the environment using the
* {AWS.EnvironmentCredentials} class with the 'AWS' and 'AMAZON' prefixes.
*
* ## Setting Providers
*
* Each provider in the {providers} list should be a function that returns
* a {AWS.Credentials} object, or a hardcoded credentials object. The function
* form allows for delayed execution of the credential construction.
*
* ## Resolving Credentials from a Chain
*
* Call {resolve} to return the first valid credential object that can be
* loaded by the provider chain.
*
* For example, to resolve a chain with a custom provider that checks a file
* on disk after the set of {defaultProviders}:
*
* ```javascript
* var diskProvider = new AWS.FileSystemCredentials('./creds.json');
* var chain = new AWS.CredentialProviderChain();
* chain.providers.push(diskProvider);
* chain.resolve();
* ```
*
* The above code will return the `diskProvider` object if the
* file contains credentials and the `defaultProviders` do not contain
* any credential settings.
*
* @!attribute providers
* @return [Array<AWS.Credentials, Function>]
* a list of credentials objects or functions that return credentials
* objects. If the provider is a function, the function will be
* executed lazily when the provider needs to be checked for valid
* credentials. By default, this object will be set to the
* {defaultProviders}.
* @see defaultProviders
*/
AWS.CredentialProviderChain = AWS.util.inherit(AWS.Credentials, {
/**
* Creates a new CredentialProviderChain with a default set of providers
* specified by {defaultProviders}.
*/
constructor: function CredentialProviderChain(providers) {
if (providers) {
this.providers = providers;
} else {
this.providers = AWS.CredentialProviderChain.defaultProviders.slice(0);
}
},
/**
* Resolves the provider chain by searching for the first set of
* credentials in {providers}.
*
* @callback callback function(err, credentials)
* Called when the provider resolves the chain to a credentials object
* or null if no credentials can be found.
*
* @param err [Error] the error object returned if no credentials are
* found.
* @param credentials [AWS.Credentials] the credentials object resolved
* by the provider chain.
* @return [AWS.CredentialProviderChain] the provider, for chaining.
*/
resolve: function resolve(callback) {
if (this.providers.length === 0) {
callback(new Error('No providers'));
return this;
}
var index = 0;
var providers = this.providers.slice(0);
function resolveNext(err, creds) {
if ((!err && creds) || index === providers.length) {
callback(err, creds);
return;
}
var provider = providers[index++];
if (typeof provider === 'function') {
creds = provider.call();
} else {
creds = provider;
}
if (creds.get) {
creds.get(function(err) {
resolveNext(err, err ? null : creds);
});
} else {
resolveNext(null, creds);
}
}
resolveNext();
return this;
}
});
/**
* The default set of providers used by a vanilla CredentialProviderChain.
*/
AWS.CredentialProviderChain.defaultProviders = [];
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