diff --git a/docs/reference/commandline/run.md b/docs/reference/commandline/run.md index 0585294f4d..5a374afa8d 100644 --- a/docs/reference/commandline/run.md +++ b/docs/reference/commandline/run.md @@ -128,27 +128,58 @@ Use `docker ps -a` to view a list of all containers, including those that are st ## Examples -### Assign name and allocate pseudo-TTY (--name, -it) +### Assign name (--name) + +The `--name` flag lets you specify a custom identifier for a container. The +following example runs a container named `test` using the `nginx:alpine` image +in [detached mode](#detach). ```console -$ docker run --name test -it debian - -root@d6c0fe130dba:/# exit 13 -$ echo $? -13 -$ docker ps -a | grep test -d6c0fe130dba debian:7 "/bin/bash" 26 seconds ago Exited (13) 17 seconds ago test +$ docker run --name test -d nginx:alpine +4bed76d3ad428b889c56c1ecc2bf2ed95cb08256db22dc5ef5863e1d03252a19 +$ docker ps +CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES +4bed76d3ad42 nginx:alpine "/docker-entrypoint.…" 1 second ago Up Less than a second 80/tcp test ``` -This example runs a container named `test` using the `debian:latest` -image. The `-it` instructs Docker to allocate a pseudo-TTY connected to -the container's stdin; creating an interactive `bash` shell in the container. -The example quits the `bash` shell by entering -`exit 13`, passing the exit code on to the caller of -`docker run`, and recording it in the `test` container's metadata. +You can reference the container by name with other commands. For example, the +following commands stop and remove a container named `test`: + +```console +$ docker stop test +test +$ docker rm test +test +``` + +If you don't specify a custom name using the `--name` flag, the daemon assigns +a randomly generated name, such as `vibrant_cannon`, to the container. Using a +custom-defined name provides the benefit of having an easy-to-remember ID for a +container. + +Moreover, if you connect the container to a user-defined bridge network, other +containers on the same network can refer to the container by name via DNS. + +```console +$ docker network create mynet +cb79f45948d87e389e12013fa4d969689ed2c3316985dd832a43aaec9a0fe394 +$ docker run --name test --net mynet -d nginx:alpine +58df6ecfbc2ad7c42d088ed028d367f9e22a5f834d7c74c66c0ab0485626c32a +$ docker run --net mynet busybox:latest ping test +PING test (172.18.0.2): 56 data bytes +64 bytes from 172.18.0.2: seq=0 ttl=64 time=0.073 ms +64 bytes from 172.18.0.2: seq=1 ttl=64 time=0.411 ms +64 bytes from 172.18.0.2: seq=2 ttl=64 time=0.319 ms +64 bytes from 172.18.0.2: seq=3 ttl=64 time=0.383 ms +... +``` ### Capture container ID (--cidfile) +To help with automation, you can have Docker write the container ID out to a +file of your choosing. This is similar to how some programs might write out +their process ID to a file (you might've seen them as PID files): + ```console $ docker run --cidfile /tmp/docker_test.cid ubuntu echo "test" ``` diff --git a/docs/reference/run.md b/docs/reference/run.md index db298c86c3..4f43d7eba7 100644 --- a/docs/reference/run.md +++ b/docs/reference/run.md @@ -22,14 +22,43 @@ A `docker run` command takes the following form: $ docker run [OPTIONS] IMAGE[:TAG|@DIGEST] [COMMAND] [ARG...] ``` -The `docker run` command must specify an [image](https://docs.docker.com/glossary/#image) +The `docker run` command must specify an [image reference](#image-references) to create the container from. +### Image references + +The image reference is the name and version of the image. You can use the image +reference to create or run a container based on an image. + +- `docker run IMAGE[:TAG][@DIGEST]` +- `docker create IMAGE[:TAG][@DIGEST]` + +An image tag is the image version, which defaults to `latest` when omitted. Use +the tag to run a container from specific version of an image. For example, to +run version `23.10` of the `ubuntu` image: `docker run ubuntu:23.10`. + +#### Image digests + +Images using the v2 or later image format have a content-addressable identifier +called a digest. As long as the input used to generate the image is unchanged, +the digest value is predictable. + +The following example runs a container from the `alpine` image with the +`sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0` digest: + +```console +$ docker run alpine@sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0 date +``` + +### Options + `[OPTIONS]` let you configure options for the container. For example, you can give the container a name (`--name`), or run it as a background process (`-d`). You can also set options to control things like resource constraints and networking. +### Commands and arguments + You can use the `[COMMAND]` and `[ARG...]` positional arguments to specify commands and arguments for the container to run when it starts up. For example, you can specify `sh` as the `[COMMAND]`, combined with the `-i` and `-t` flags, @@ -95,55 +124,41 @@ For more information about re-attaching to a background container, see ## Container identification -### Name (--name) - -The operator can identify a container in three ways: +You can identify a container in three ways: | Identifier type | Example value | |:----------------------|:-------------------------------------------------------------------| -| UUID long identifier | "f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778" | -| UUID short identifier | "f78375b1c487" | -| Name | "evil_ptolemy" | +| UUID long identifier | `f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778` | +| UUID short identifier | `f78375b1c487` | +| Name | `evil_ptolemy` | -The UUID identifiers come from the Docker daemon. If you do not assign a -container name with the `--name` option, then the daemon generates a random -string name for you. Defining a `name` can be a handy way to add meaning to a -container. If you specify a `name`, you can use it when referencing the -container within a Docker network. This works for both background and foreground -Docker containers. +The UUID identifier is a random ID assigned to the container by the daemon. -> **Note** -> -> Containers on the default bridge network must be linked to communicate by name. +The daemon generates a random string name for containers automatically. You can +also defined a custom name using [the `--name` flag](./commandline/run.md#name). +Defining a `name` can be a handy way to add meaning to a container. If you +specify a `name`, you can use it when referring to the container in a +user-defined network. This works for both background and foreground Docker +containers. -### PID equivalent +A container identifier is not the same thing as an image reference. The image +reference specifies which image to use when you run a container. You can't run +`docker exec nginx:alpine sh` to open a shell in a container based on the +`nginx:alpine` image, because `docker exec` expects a container identifier +(name or ID), not an image. -Finally, to help with automation, you can have Docker write the -container ID out to a file of your choosing. This is similar to how some -programs might write out their process ID to a file (you've seen them as -PID files): - - --cidfile="": Write the container ID to the file - -### Image[:tag] - -While not strictly a means of identifying a container, you can specify a version of an -image you'd like to run the container with by adding `image[:tag]` to the command. For -example, `docker run ubuntu:22.04`. - -### Image[@digest] - -Images using the v2 or later image format have a content-addressable identifier -called a digest. As long as the input used to generate the image is unchanged, -the digest value is predictable and referenceable. - -The following example runs a container from the `alpine` image with the -`sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0` digest: +While the image used by a container is not an identifier for the container, you +find out the IDs of containers using an image by using the `--filter` flag. For +example, the following `docker ps` command gets the IDs of all running +containers based on the `nginx:alpine` image: ```console -$ docker run alpine@sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0 date +$ docker ps -q --filter ancestor=nginx:alpine ``` +For more information about using filters, see +[Filtering](https://docs.docker.com/config/filter/). + ## PID settings (--pid) --pid="" : Set the PID (Process) Namespace mode for the container,