@azure/identity/dist/commonjs/credentials/managedIdentityCredential/imdsMsi.js

Provides credential implementations for Azure SDK libraries that can authenticate with Microsoft Entra ID

"use strict";
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
Object.defineProperty(exports, "__esModule", { value: true });
exports.imdsMsi = void 0;
const core_rest_pipeline_1 = require("@azure/core-rest-pipeline");
const core_util_1 = require("@azure/core-util");
const logging_js_1 = require("../../util/logging.js");
const utils_js_1 = require("./utils.js");
const tracing_js_1 = require("../../util/tracing.js");
const msiName = "ManagedIdentityCredential - IMDS";
const logger = (0, logging_js_1.credentialLogger)(msiName);
const imdsHost = "http://169.254.169.254";
const imdsEndpointPath = "/metadata/identity/oauth2/token";
/**
 * Generates an invalid request options to get a response quickly from IMDS endpoint.
 * The response indicates the availability of IMSD service; otherwise the request would time out.
 */
function prepareInvalidRequestOptions(scopes) {
    const resource = (0, utils_js_1.mapScopesToResource)(scopes);
    if (!resource) {
        throw new Error(`${msiName}: Multiple scopes are not supported.`);
    }
    // Pod Identity will try to process this request even if the Metadata header is missing.
    // We can exclude the request query to ensure no IMDS endpoint tries to process the ping request.
    const url = new URL(imdsEndpointPath, process.env.AZURE_POD_IDENTITY_AUTHORITY_HOST ?? imdsHost);
    const rawHeaders = {
        Accept: "application/json",
        // intentionally leave out the Metadata header to invoke an error from IMDS endpoint.
    };
    return {
        // intentionally not including any query
        url: `${url}`,
        method: "GET",
        headers: (0, core_rest_pipeline_1.createHttpHeaders)(rawHeaders),
    };
}
/**
 * Defines how to determine whether the Azure IMDS MSI is available.
 *
 * Actually getting the token once we determine IMDS is available is handled by MSAL.
 */
exports.imdsMsi = {
    name: "imdsMsi",
    async isAvailable(options) {
        const { scopes, identityClient, getTokenOptions } = options;
        const resource = (0, utils_js_1.mapScopesToResource)(scopes);
        if (!resource) {
            logger.info(`${msiName}: Unavailable. Multiple scopes are not supported.`);
            return false;
        }
        // if the PodIdentityEndpoint environment variable was set no need to probe the endpoint, it can be assumed to exist
        if (process.env.AZURE_POD_IDENTITY_AUTHORITY_HOST) {
            return true;
        }
        if (!identityClient) {
            throw new Error("Missing IdentityClient");
        }
        const requestOptions = prepareInvalidRequestOptions(resource);
        return tracing_js_1.tracingClient.withSpan("ManagedIdentityCredential-pingImdsEndpoint", getTokenOptions ?? {}, async (updatedOptions) => {
            requestOptions.tracingOptions = updatedOptions.tracingOptions;
            // Create a request with a timeout since we expect that
            // not having a "Metadata" header should cause an error to be
            // returned quickly from the endpoint, proving its availability.
            const request = (0, core_rest_pipeline_1.createPipelineRequest)(requestOptions);
            // Default to 1000 if the default of 0 is used.
            // Negative values can still be used to disable the timeout.
            request.timeout = updatedOptions.requestOptions?.timeout || 1000;
            // This MSI uses the imdsEndpoint to get the token, which only uses http://
            request.allowInsecureConnection = true;
            let response;
            try {
                logger.info(`${msiName}: Pinging the Azure IMDS endpoint`);
                response = await identityClient.sendRequest(request);
            }
            catch (err) {
                // If the request failed, or Node.js was unable to establish a connection,
                // or the host was down, we'll assume the IMDS endpoint isn't available.
                if ((0, core_util_1.isError)(err)) {
                    logger.verbose(`${msiName}: Caught error ${err.name}: ${err.message}`);
                }
                // This is a special case for Docker Desktop which responds with a 403 with a message that contains "A socket operation was attempted to an unreachable network" or "A socket operation was attempted to an unreachable host"
                // rather than just timing out, as expected.
                logger.info(`${msiName}: The Azure IMDS endpoint is unavailable`);
                return false;
            }
            if (response.status === 403) {
                if (response.bodyAsText?.includes("unreachable")) {
                    logger.info(`${msiName}: The Azure IMDS endpoint is unavailable`);
                    logger.info(`${msiName}: ${response.bodyAsText}`);
                    return false;
                }
            }
            // If we received any response, the endpoint is available
            logger.info(`${msiName}: The Azure IMDS endpoint is available`);
            return true;
        });
    },
};
//# sourceMappingURL=imdsMsi.js.map