How can I persist Docker authentication in the free Google Cloud Shell?

When you’re using the free Google Cloud Shell, the environment is meant to be ephemeral. This means that after your session ends the Docker configuration—including any credentials stored using docker login—is lost. There isn’t a built‑in durable credential store available out of the box in the free version.

Here are a couple of workarounds:

1. Reauthenticate Each Session:
   At the start of each session, you can run the necessary docker login commands. This ensures that your session has the latest credentials even though they aren’t persisted past the session.

2. Inline Authentication (with Caution):
   In some examples (like the one using Base-64 encoded JSON structures for authentication) you might embed credentials in your API calls. For example:

   CONSOLECopied
   $ JSON=$(echo '{"username": "your_user", "password": "your_pass", "serveraddress": "index.docker.io/v1/"}' | base64)
   
   $ curl --unix-socket /var/run/docker.sock \
     -H "Content-Type: application/tar" \
     -X POST "http://localhost/v1.47/images/create?fromImage=alpine" \
     -H "X-Registry-Auth" \
     -d "$JSON"

   This approach avoids the need to run docker login every time, but it exposes your credentials in your command history and other logs, so use it with extreme care.

For secure and persistent storage of credentials, you’d typically rely on the Docker credentials store or Docker Desktop’s integrated credential management. However, those options aren’t available in the free ephemeral Cloud Shell.

In summary, there isn’t a built‑in method in free Cloud Shell to make authenticated Docker sessions persistent. You’ll need to script or manually re-authenticate each time.

In the free version of Google Cloud Shell the environment is meant to be ephemeral, so any authentication state (like that from a previous docker login) is not persisted between sessions. This means you’ll need to re-authenticate each time you start a new session.

Here are a few workarounds you might consider:

1. Manual Login on Each Session:
   Run the docker login command at the start of every session. For example:

   BASHCopied
   docker login -u YOUR_USERNAME -p YOUR_PASSWORD

   This will temporarily store the credentials in your session. Just keep in mind that this does leave the credentials in your shell's history.

2. Scripting the Authentication Process:
   Save a script that performs the authentication automatically on session startup (for example, in your ~/.bashrc). Be cautious with this approach because embedding passwords in scripts can present a security risk. Alternatively, you might encode the credentials and pass them as needed through commands similar to those shown in the Docker API examples (where credentials are passed as Base-64-encoded JSON).

3. Using Environment-Specific Credential Helpers:
   If it fits your workflow, investigate using credential helper tools. For example, Docker integrates with tools that securely store credentials. However, configuring these in an ephemeral environment like Cloud Shell may require additional setup each session.

In summary, while there isn’t a built-in way to have a persistent Docker authentication state in the free version of Google Cloud Shell, automating the re-authentication or using encoded credentials are common approaches to work around the limitation. Always be mindful of security, especially when handling credentials in scripts or command histories.