Let's break down why your current approach exposes credentials and how to fix it properly:

Why Your Credentials Are Leaking #

When you assign the masked environment variables USERNAME and PASSWORD to global Groovy variables (username and password), you bypass Jenkins' built-in masking mechanism. Environment variables inside withCredentials are automatically masked in logs, but Groovy variables don't get this protection—if these variables are ever logged (even accidentally, like a debug echo or a plugin that outputs variable values), the plaintext credentials will show up.

Secure Solutions to Protect Your Credentials #

1. Keep All Credential Usage Inside the withCredentials Block (Best Practice)

The safest approach is to never move credentials outside the withCredentials scope. Perform every action that needs the credentials directly inside the block:

node(){ 
    withCredentials([usernamePassword(
        credentialsId: '6827ae64-c211-4bb9-b4cd-64eeca90be6f', 
        passwordVariable: 'PASSWORD', 
        usernameVariable: 'USERNAME'
    )]) { 
        // Do EVERYTHING that needs credentials here
        // Example: Call an API with basic auth
        sh 'curl -u "${USERNAME}:${PASSWORD}" https://your-api-endpoint.com'
        // Example: Log in to a Docker registry
        sh 'docker login -u "${USERNAME}" -p "${PASSWORD}" your-registry.io'
    }
}

Jenkins automatically masks the PASSWORD (and optionally USERNAME if configured) in console logs when using the environment variables directly.

2. Wrap Credentials in Jenkins' Secret Class (If You Must Use Globals)

If you absolutely need to pass credentials outside the withCredentials block (this should be a last resort), use Jenkins' hudson.util.Secret class to wrap the values. This ensures the plaintext is only exposed when explicitly retrieved, and the variable itself will show as masked in logs:

import hudson.util.Secret

def usernameSecret
def passwordSecret 

node(){ 
    withCredentials([usernamePassword(
        credentialsId: '6827ae64-c211-4bb9-b4cd-64eeca90be6f', 
        passwordVariable: 'PASSWORD', 
        usernameVariable: 'USERNAME'
    )]) { 
        usernameSecret = Secret.fromString(USERNAME)
        passwordSecret = Secret.fromString(PASSWORD)
    }

    // When you need to use the plaintext value later:
    sh "some-command --user '${usernameSecret.getPlainText()}' --pass '${passwordSecret.getPlainText()}'"
    // WARNING: Only call getPlainText() when strictly necessary, and never log the result!
}

Note: The getPlainText() method returns the unmasked value, so be extremely careful not to print this anywhere in your pipeline.

3. Audit Your Pipeline for Accidental Logging

Double-check your entire pipeline for any code that might log these variables. Remove or modify lines like:

• echo "Username is ${username}"
• print(password)
• Any plugin steps that might output variable values (check plugin documentation for logging behavior)

Key Takeaway #

The most secure way to handle Jenkins credentials is to limit their scope to the withCredentials block. Avoid storing them in global variables whenever possible—this eliminates the risk of accidental exposure entirely.

内容的提问来源于stack exchange，提问作者Yogesh Yadav