Final answer:
To log into a Docker repository, use the Docker CLI with the 'docker login' command, optionally including the private repository URL. Enter your login credentials when prompted to securely authenticate to the registry.
Step-by-step explanation:
To log in to a Docker repository, you typically need to use the Docker command-line interface (CLI). You'll need to have Docker installed on your machine, and then you can use the docker login command followed by the repository's URL, if it's a private repository or a third-party registry other than Docker Hub. For Docker Hub, you can directly run docker login and enter your Docker Hub username and password when prompted.
Here is an example command to log in to Docker Hub:
docker login --username yourusername --password yourpassword
If you're using a third-party registry, you'll need to specify its URL:
docker login some.registry.com --username yourusername --password yourpassword
Remember, it's considered insecure to provide your password on the command line, and instead, you should enter it when prompted for better security. Additionally, Docker also supports saving credentials in a config file or using access tokens instead of a password for more secure authentication methods.