![]() While Docker image tags are mutable, Docker images have a content-addressable identifier called a digest which is a sha256 fingerprint that is always guaranteed to be immutable. There’s no guarantee that the same tag name will always refer to the same actual image since new versions of an image can be assigned an existing tag.įor example, the “alpine” tag for rabbitmq is always updated when a new version of rabbitmq is released or when the maintainers decide to use a new Alpine version. Is Docker Tag immutable?Īn important thing to bear in mind about Docker tags is that they’re mutable by design. The images without “-management” don’t use the management plugin. For instance, when it comes to the RabbitMQ images, the ones with “-management” use the management plugin, which allows you to access an admin web interface for RabbitMQ. You can think of tags as a way to distribute several different editions or variations of the same image. Then click on “tags.” You’ll see several different tags listed: Go to the page for the official RabbitMQ image. What Is a Docker Tag?Ī tag in Docker is a named reference to a particular version of an image. We also assume a basic knowledge of Docker! Docker Tag Fundamentalsįirst we’ll answer some fundamental questions about tags in Docker. If you don’t have one, go to the sign-up page and create a free account. You’ll also need an account on Docker Hub. Go to the installation page and follow the instructions for your platform if you need to. Second, you need to have Docker installed on your system. First, we expect you to be comfortable working with the command line. If you want to follow along with this post there are a few requirements. This post aims to make your Docker journey easier by taking a deep dive into the docker tag command. There are countless commands and each of them has many options. However, actually learning how to work with Docker can feel a little overwhelming. Whoever has this package will be able to run the application, and it’s all but guaranteed to behave as expected. You put your software and its dependencies inside a “package” and distribute it. Without -t and bash can be used, when you dont want to attach the docker containers process to your shell.The main principle behind Docker and containerization isn’t too difficult to grasp. Without -i can be used for commands, that don't need inputs. i for being able to send inputs via STDIN for example with the keyboard to the bash in the container t for attaching the bash process to our terminal ![]() ![]() Therefore, we need to combine the two: ~]$ sudo docker exec -i -t 69e937450dab lsīin boot dev docker-entrypoint.d docker-entrypoint.sh etc hi home lib lib64 media mnt opt proc root run sbin srv sys tmp usr recap: Adding the flag will do the deal: ~]$ sudo docker exec -t 69e937450dab this does not really help, because we need an input stream, which takes our commands and can be received by the bash. You will see nothing, because the process started in the container. Now, let us suppose, you want the bash to start as process: sudo docker exec 69e937450dab bash ~]$ echo test | sudo docker exec -i 69e937450dab cat ![]() Nothing will show, because there is no input stream going to the docker container. If your command needs an input like cat, you can try: ~]$ echo test | sudo docker exec 69e937450dab cat Normal execution without any flags: ~]$ sudo docker exec 69e937450dab ls ![]()
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