133 lines
4.3 KiB
JavaScript
133 lines
4.3 KiB
JavaScript
var AWS = require('./core');
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require('./http');
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var inherit = AWS.util.inherit;
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/**
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* Represents a metadata service available on EC2 instances. Using the
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* {request} method, you can receieve metadata about any available resource
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* on the metadata service.
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*
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* You can disable the use of the IMDS by setting the AWS_EC2_METADATA_DISABLED
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* environment variable to a truthy value.
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*
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* @!attribute [r] httpOptions
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* @return [map] a map of options to pass to the underlying HTTP request:
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*
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* * **timeout** (Number) — a timeout value in milliseconds to wait
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* before aborting the connection. Set to 0 for no timeout.
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*
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* @!macro nobrowser
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*/
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AWS.MetadataService = inherit({
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/**
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* @return [String] the hostname of the instance metadata service
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*/
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host: '169.254.169.254',
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/**
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* @!ignore
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*/
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/**
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* Default HTTP options. By default, the metadata service is set to not
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* timeout on long requests. This means that on non-EC2 machines, this
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* request will never return. If you are calling this operation from an
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* environment that may not always run on EC2, set a `timeout` value so
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* the SDK will abort the request after a given number of milliseconds.
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*/
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httpOptions: { timeout: 0 },
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/**
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* Creates a new MetadataService object with a given set of options.
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*
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* @option options host [String] the hostname of the instance metadata
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* service
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* @option options httpOptions [map] a map of options to pass to the
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* underlying HTTP request:
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*
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* * **timeout** (Number) — a timeout value in milliseconds to wait
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* before aborting the connection. Set to 0 for no timeout.
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* @option options maxRetries [Integer] the maximum number of retries to
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* perform for timeout errors
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* @option options retryDelayOptions [map] A set of options to configure the
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* retry delay on retryable errors. See AWS.Config for details.
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*/
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constructor: function MetadataService(options) {
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AWS.util.update(this, options);
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},
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/**
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* Sends a request to the instance metadata service for a given resource.
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*
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* @param path [String] the path of the resource to get
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* @callback callback function(err, data)
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* Called when a response is available from the service.
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* @param err [Error, null] if an error occurred, this value will be set
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* @param data [String, null] if the request was successful, the body of
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* the response
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*/
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request: function request(path, callback) {
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if (process.env[AWS.util.imdsDisabledEnv]) {
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callback(new Error('EC2 Instance Metadata Service access disabled'));
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return;
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}
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path = path || '/';
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var httpRequest = new AWS.HttpRequest('http://' + this.host + path);
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httpRequest.method = 'GET';
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AWS.util.handleRequestWithRetries(httpRequest, this, callback);
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},
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/**
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* @api private
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*/
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loadCredentialsCallbacks: [],
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/**
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* Loads a set of credentials stored in the instance metadata service
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*
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* @api private
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* @callback callback function(err, credentials)
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* Called when credentials are loaded from the resource
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* @param err [Error] if an error occurred, this value will be set
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* @param credentials [Object] the raw JSON object containing all
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* metadata from the credentials resource
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*/
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loadCredentials: function loadCredentials(callback) {
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var self = this;
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var basePath = '/latest/meta-data/iam/security-credentials/';
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self.loadCredentialsCallbacks.push(callback);
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if (self.loadCredentialsCallbacks.length > 1) { return; }
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function callbacks(err, creds) {
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var cb;
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while ((cb = self.loadCredentialsCallbacks.shift()) !== undefined) {
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cb(err, creds);
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}
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}
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self.request(basePath, function (err, roleName) {
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if (err) callbacks(err);
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else {
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roleName = roleName.split('\n')[0]; // grab first (and only) role
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self.request(basePath + roleName, function (credErr, credData) {
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if (credErr) callbacks(credErr);
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else {
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try {
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var credentials = JSON.parse(credData);
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callbacks(null, credentials);
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} catch (parseError) {
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callbacks(parseError);
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}
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}
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});
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}
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});
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}
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});
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/**
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* @api private
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*/
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module.exports = AWS.MetadataService;
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