shrinking /nix/store/f2vs29jibd7lwxyj35r9h87h6brgdysz-hello-2.12.1/bin/hello
checking for references to /build/ in /nix/store/f2vs29jibd7lwxyj35r9h87h6brgdysz-hello-2.12.1...
gzipping man pages under /nix/store/f2vs29jibd7lwxyj35r9h87h6brgdysz-hello-2.12.1/share/man/
patching script interpreter paths in /nix/store/f2vs29jibd7lwxyj35r9h87h6brgdysz-hello-2.12.1
stripping (with command strip and flags -S -p) in  /nix/store/f2vs29jibd7lwxyj35r9h87h6brgdysz-hello-2.12.1/bin

[nix-shell:~]$ $out/bin/hello
Hello, world!
```
:::

:::{.example #ex-dockerTools-streamNixShellImage-extendingBuildInputs}
# Adding extra packages to a Docker image built with `streamNixShellImage`

This example shows how to add extra packages to an image built with `streamNixShellImage`.
In this case, we'll add the `cowsay` package.
The Docker image generated will have a name like `hello-<version>-env` and tag `latest`.
This example uses [](#ex-dockerTools-streamNixShellImage-hello) as a starting point.

```nix
{
  dockerTools,
  cowsay,
  hello,
}:
dockerTools.streamNixShellImage {
  tag = "latest";
  drv = hello.overrideAttrs (old: {
    nativeBuildInputs = old.nativeBuildInputs or [ ] ++ [
      cowsay
    ];
  });
}
```

The result of building this package is a script which can be run and piped into `docker image load` to load the generated image.

```shell
$ nix-build
(some output removed for clarity)
/nix/store/h5abh0vljgzg381lna922gqknx6yc0v7-stream-hello-2.12.1-env

$ /nix/store/h5abh0vljgzg381lna922gqknx6yc0v7-stream-hello-2.12.1-env | docker image load
(some output removed for clarity)
Loaded image: hello-2.12.1-env:latest
```

After starting an interactive container, we can verify the extra package is available by running `cowsay`:

```shell
$ docker container run -it hello-2.12.1-env:latest
[nix-shell:~]$ cowsay "Hello, world!"
 _______________
< Hello, world! >
 ---------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||
```
:::

:::{.example #ex-dockerTools-streamNixShellImage-addingShellHook}
# Adding a `shellHook` to a Docker image built with `streamNixShellImage`

This example shows how to add a `shellHook` command to an image built with `streamNixShellImage`.
In this case, we'll simply output the string `Hello, world!`.
The Docker image generated will have a name like `hello-<version>-env` and tag `latest`.
This example uses [](#ex-dockerTools-streamNixShellImage-hello) as a starting point.

```nix
{ dockerTools, hello }:
dockerTools.streamNixShellImage {
  tag = "latest";
  drv = hello.overrideAttrs (old: {
    shellHook = ''
      ${old.shellHook or ""}
      echo "Hello, world!"
    '';
  });
}
```

The result of building this package is a script which can be run and piped into `docker image load` to load the generated image.

```shell
$ nix-build
(some output removed for clarity)
/nix/store/iz4dhdvgzazl5vrgyz719iwjzjy6xlx1-stream-hello-2.12.1-env

$ /nix/store/iz4dhdvgzazl5vrgyz719iwjzjy6xlx1-stream-hello-2.12.1-env | docker image load
(some output removed for clarity)
Loaded image: hello-2.12.1-env:latest
```

After starting an interactive container, we can see the result of the `shellHook`:

```shell
$ docker container run -it hello-2.12.1-env:latest
Hello, world!

[nix-shell:~]$
```
:::