The "docker container run" command has two options that allow you to set environment variables for your containers:

-e, --env NAME=VALUE         Set environment variables
    --env-file file          Read in a file of environment variables

Let's try the option "-e" ("--env"):

$ docker container run --rm --env my_env_var_1="my env var 1 value" --env my_env_var_2="my env var 2 value" ubuntu:latest /bin/bash -c "env | grep my_env_var_"

my_env_var_1=my env var 1 value
my_env_var_2=my env var 2 value

The two environment variables were set properly. The applications running inside the container can use them as they would in a regular deployment in a native host.

In some cases, setting environment variables using the option "--env" can be cumbersome especially if we want to set many of them. Optionally, you can group all the environment variables in a property file and use the option "--env-file" to pass the file to "docker container run" command.

Let's create a property file:

$ vi env-file-1

my_env_var_1=my env var 1 value
my_env_var_2=my env var 2 value
my_env_var_3=my env var 3 value

Let's use the option "--env-file":

$ docker container run --rm --env-file env-file-1 ubuntu:latest /bin/bash -c "env | grep my_env_var_"

my_env_var_1=my env var 1 value
my_env_var_2=my env var 2 value
my_env_var_3=my env var 3 value

The "docker container run" command has two options that allow you to set labels for your containers:

-l, --label list                       Set meta data on a container
    --label-file list                  Read in a line delimited file of labels

Let's try the option "-l" ("--label"):

$ docker container run --rm -d --label my_label_1="my label 1 value" --label my_label_2="my label 2 value" nginx:latest

9da697d8336291e8afb968224ff9402bf2d1dfc904275c7c392e44d8c1155e6b

Let's check the labels:

$ docker container inspect b0411f9636 --format '{{json .Config.Labels }}' | jq

{
  "my_label_1": "my label 1 value",
  "my_label_2": "my label 2 value"
}

The two labels were set properly. We can use them to filter containers:

$ docker container ls -a --filter label="my_label_1=my label 1 value"

CONTAINER ID   IMAGE          COMMAND                  CREATED         STATUS         PORTS     NAMES
b0411f9636d8   nginx:latest   "/docker-entrypoint.…"   9 minutes ago   Up 9 minutes   80/tcp    modest_ishizaka

In some cases, setting labels using the option "--label" can be cumbersome especially if we want to set many of them. Optionally, you can group all the labels in a property file and use the option "--label-file" to pass the file to "docker container run" command.

Let's create a property file:

$ vi label-file-1

my_label_1=my label 1 value
my_label_2=my label 2 value
my_label_3=my label 3 value

Let's use the option "--env-file":

$ docker container run --rm -d --label-file label-file-1 nginx:latest

cc5164ddc8993f3d383e00345195dc495d72479271752bf812f11024208cc109

Let's check the labels:

$ docker container inspect cc5164ddc --format '{{json .Config.Labels }}' | jq

{
  "my_label_1": "my label 1 value",
  "my_label_2": "my label 2 value",
  "my_label_3": "my label 3 value"
}

When you run a container, it gets automatically the /etc/hostname file initialized with its ID:

$ docker container run --rm ubuntu:latest /bin/bash -c "cat /etc/hostname"

20f335d7ac41

To assign a specific host name to the container, we can use the option -h (--hostname) with the command docker container run:

$ docker container run --rm --hostname ubuntu-latest ubuntu:latest /bin/bash -c "cat /etc/hostname"

ubuntu-latest