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Common AWS credentials library (#108)
Move AWS signature auth to independent script
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/* | ||
* Copyright 2023 F5, Inc. | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
*/ | ||
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import utils from "./utils.js"; | ||
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const fs = require('fs'); | ||
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/** | ||
* Get the current session token from either the instance profile credential | ||
* cache or environment variables. | ||
* | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @returns {string} current session token or empty string | ||
*/ | ||
function sessionToken(r) { | ||
const credentials = readCredentials(r); | ||
if (credentials.sessionToken) { | ||
return credentials.sessionToken; | ||
} | ||
return ''; | ||
} | ||
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/** | ||
* Get the instance profile credentials needed to authenticated against S3 from | ||
* a backend cache. If the credentials cannot be found, then return undefined. | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @returns {undefined|{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string|null), expiration: (string|null)}} AWS instance profile credentials or undefined | ||
*/ | ||
function readCredentials(r) { | ||
// TODO: Change the generic constants naming for multiple AWS services. | ||
if ('S3_ACCESS_KEY_ID' in process.env && 'S3_SECRET_KEY' in process.env) { | ||
const sessionToken = 'S3_SESSION_TOKEN' in process.env ? | ||
process.env['S3_SESSION_TOKEN'] : null; | ||
return { | ||
accessKeyId: process.env['S3_ACCESS_KEY_ID'], | ||
secretAccessKey: process.env['S3_SECRET_KEY'], | ||
sessionToken: sessionToken, | ||
expiration: null | ||
}; | ||
} | ||
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if ("variables" in r && r.variables.cache_instance_credentials_enabled == 1) { | ||
return _readCredentialsFromKeyValStore(r); | ||
} else { | ||
return _readCredentialsFromFile(); | ||
} | ||
} | ||
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/** | ||
* Read credentials from the NGINX Keyval store. If it is not found, then | ||
* return undefined. | ||
* | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @returns {undefined|{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string), expiration: (string)}} AWS instance profile credentials or undefined | ||
* @private | ||
*/ | ||
function _readCredentialsFromKeyValStore(r) { | ||
const cached = r.variables.instance_credential_json; | ||
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if (!cached) { | ||
return undefined; | ||
} | ||
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try { | ||
return JSON.parse(cached); | ||
} catch (e) { | ||
utils.debug_log(r, `Error parsing JSON value from r.variables.instance_credential_json: ${e}`); | ||
return undefined; | ||
} | ||
} | ||
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/** | ||
* Read the contents of the credentials file into memory. If it is not | ||
* found, then return undefined. | ||
* | ||
* @returns {undefined|{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string), expiration: (string)}} AWS instance profile credentials or undefined | ||
* @private | ||
*/ | ||
function _readCredentialsFromFile() { | ||
const credsFilePath = _credentialsTempFile(); | ||
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try { | ||
const creds = fs.readFileSync(credsFilePath); | ||
return JSON.parse(creds); | ||
} catch (e) { | ||
/* Do not throw an exception in the case of when the | ||
credentials file path is invalid in order to signal to | ||
the caller that such a file has not been created yet. */ | ||
if (e.code === 'ENOENT') { | ||
return undefined; | ||
} | ||
throw e; | ||
} | ||
} | ||
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/** | ||
* Returns the path to the credentials temporary cache file. | ||
* | ||
* @returns {string} path on the file system to credentials cache file | ||
* @private | ||
*/ | ||
function _credentialsTempFile() { | ||
if (process.env['S3_CREDENTIALS_TEMP_FILE']) { | ||
return process.env['S3_CREDENTIALS_TEMP_FILE']; | ||
} | ||
if (process.env['TMPDIR']) { | ||
return `${process.env['TMPDIR']}/credentials.json` | ||
} | ||
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return '/tmp/credentials.json'; | ||
} | ||
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/** | ||
* Write the instance profile credentials to a caching backend. | ||
* | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @param credentials {{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string), expiration: (string)}} AWS instance profile credentials | ||
*/ | ||
function writeCredentials(r, credentials) { | ||
/* Do not bother writing credentials if we are running in a mode where we | ||
do not need instance credentials. */ | ||
if (process.env['S3_ACCESS_KEY_ID'] && process.env['S3_SECRET_KEY']) { | ||
return; | ||
} | ||
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if (!credentials) { | ||
throw `Cannot write invalid credentials: ${JSON.stringify(credentials)}`; | ||
} | ||
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if ("variables" in r && r.variables.cache_instance_credentials_enabled == 1) { | ||
_writeCredentialsToKeyValStore(r, credentials); | ||
} else { | ||
_writeCredentialsToFile(credentials); | ||
} | ||
} | ||
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/** | ||
* Write the instance profile credentials to the NGINX Keyval store. | ||
* | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @param credentials {{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string), expiration: (string)}} AWS instance profile credentials | ||
* @private | ||
*/ | ||
function _writeCredentialsToKeyValStore(r, credentials) { | ||
r.variables.instance_credential_json = JSON.stringify(credentials); | ||
} | ||
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/** | ||
* Write the instance profile credentials to a file on the file system. This | ||
* file will be quite small and should end up in the file cache relatively | ||
* quickly if it is repeatedly read. | ||
* | ||
* @param r {Request} HTTP request object (not used, but required for NGINX configuration) | ||
* @param credentials {{accessKeyId: (string), secretAccessKey: (string), sessionToken: (string), expiration: (string)}} AWS instance profile credentials | ||
* @private | ||
*/ | ||
function _writeCredentialsToFile(credentials) { | ||
fs.writeFileSync(_credentialsTempFile(), JSON.stringify(credentials)); | ||
} | ||
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export default { | ||
readCredentials, | ||
sessionToken, | ||
writeCredentials | ||
} |
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