# Examples of using the docker tools to build packages. # # This file defines several docker images. In order to use an image, # build its derivation with `nix-build`, and then load the result with # `docker load`. For example: # # $ nix-build '' -A dockerTools.examples.redis # $ docker load < result { pkgs, buildImage, buildLayeredImage, fakeNss, pullImage, shadowSetup, buildImageWithNixDb, pkgsCross }: let nixosLib = import ../../../nixos/lib { # Experimental features need testing too, but there's no point in warning # about it, so we enable the feature flag. featureFlags.minimalModules = {}; }; evalMinimalConfig = module: nixosLib.evalModules { modules = [ module ]; }; in rec { # 1. basic example bash = buildImage { name = "bash"; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; paths = [ pkgs.bashInteractive ]; pathsToLink = [ "/bin" ]; }; }; # 2. service example, layered on another image redis = buildImage { name = "redis"; tag = "latest"; # for example's sake, we can layer redis on top of bash or debian fromImage = bash; # fromImage = debian; copyToRoot = pkgs.buildEnv { name = "image-root"; paths = [ pkgs.redis ]; pathsToLink = [ "/bin" ]; }; runAsRoot = '' mkdir -p /data ''; config = { Cmd = [ "/bin/redis-server" ]; WorkingDir = "/data"; Volumes = { "/data" = {}; }; }; }; # 3. another service example nginx = let nginxPort = "80"; nginxConf = pkgs.writeText "nginx.conf" '' user nobody nobody; daemon off; error_log /dev/stdout info; pid /dev/null; events {} http { access_log /dev/stdout; server { listen ${nginxPort}; index index.html; location / { root ${nginxWebRoot}; } } } ''; nginxWebRoot = pkgs.writeTextDir "index.html" ''

Hello from NGINX

''; in buildLayeredImage { name = "nginx-container"; tag = "latest"; contents = [ fakeNss pkgs.nginx ]; extraCommands = '' # nginx still tries to read this directory even if error_log # directive is specifying another file :/ mkdir -p var/log/nginx mkdir -p var/cache/nginx ''; config = { Cmd = [ "nginx" "-c" nginxConf ]; ExposedPorts = { "${nginxPort}/tcp" = {}; }; }; }; # 4. example of pulling an image. could be used as a base for other images nixFromDockerHub = pullImage { imageName = "nixos/nix"; imageDigest = "sha256:85299d86263a3059cf19f419f9d286cc9f06d3c13146a8ebbb21b3437f598357"; sha256 = "19fw0n3wmddahzr20mhdqv6jkjn1kanh6n2mrr08ai53dr8ph5n7"; finalImageTag = "2.2.1"; finalImageName = "nix"; }; # Same example, but re-fetches every time the fetcher implementation changes. # NOTE: Only use this for testing, or you'd be wasting a lot of time, network and space. testNixFromDockerHub = pkgs.testers.invalidateFetcherByDrvHash pullImage { imageName = "nixos/nix"; imageDigest = "sha256:85299d86263a3059cf19f419f9d286cc9f06d3c13146a8ebbb21b3437f598357"; sha256 = "19fw0n3wmddahzr20mhdqv6jkjn1kanh6n2mrr08ai53dr8ph5n7"; finalImageTag = "2.2.1"; finalImageName = "nix"; }; # 5. example of multiple contents, emacs and vi happily coexisting editors = buildImage { name = "editors"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils pkgs.bash pkgs.emacs pkgs.vim pkgs.nano ]; }; }; # 6. nix example to play with the container nix store # docker run -it --rm nix nix-store -qR $(nix-build '' -A nix) nix = buildImageWithNixDb { name = "nix"; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ # nix-store uses cat program to display results as specified by # the image env variable NIX_PAGER. pkgs.coreutils pkgs.nix pkgs.bash ]; }; config = { Env = [ "NIX_PAGER=cat" # A user is required by nix # https://github.com/NixOS/nix/blob/9348f9291e5d9e4ba3c4347ea1b235640f54fd79/src/libutil/util.cc#L478 "USER=nobody" ]; }; }; # 7. example of adding something on top of an image pull by our # dockerTools chain. onTopOfPulledImage = buildImage { name = "onTopOfPulledImage"; tag = "latest"; fromImage = nixFromDockerHub; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.hello ]; }; }; # 8. regression test for erroneous use of eval and string expansion. # See issue #34779 and PR #40947 for details. runAsRootExtraCommands = pkgs.dockerTools.buildImage { name = "runAsRootExtraCommands"; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils ]; }; # The parens here are to create problematic bash to embed and eval. In case # this is *embedded* into the script (with nix expansion) the initial quotes # will close the string and the following parens are unexpected runAsRoot = ''echo "(runAsRoot)" > runAsRoot''; extraCommands = ''echo "(extraCommand)" > extraCommands''; }; # 9. Ensure that setting created to now results in a date which # isn't the epoch + 1 unstableDate = pkgs.dockerTools.buildImage { name = "unstable-date"; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils ]; }; created = "now"; }; # 10. Create a layered image layered-image = pkgs.dockerTools.buildLayeredImage { name = "layered-image"; tag = "latest"; extraCommands = ''echo "(extraCommand)" > extraCommands''; config.Cmd = [ "${pkgs.hello}/bin/hello" ]; contents = [ pkgs.hello pkgs.bash pkgs.coreutils ]; }; # 11. Create an image on top of a layered image layered-on-top = pkgs.dockerTools.buildImage { name = "layered-on-top"; tag = "latest"; fromImage = layered-image; extraCommands = '' mkdir ./example-output chmod 777 ./example-output ''; config = { Env = [ "PATH=${pkgs.coreutils}/bin/" ]; WorkingDir = "/example-output"; Cmd = [ "${pkgs.bash}/bin/bash" "-c" "echo hello > foo; cat foo" ]; }; }; # 12 Create a layered image on top of a layered image layered-on-top-layered = pkgs.dockerTools.buildLayeredImage { name = "layered-on-top-layered"; tag = "latest"; fromImage = layered-image; extraCommands = '' mkdir ./example-output chmod 777 ./example-output ''; config = { Env = [ "PATH=${pkgs.coreutils}/bin/" ]; WorkingDir = "/example-output"; Cmd = [ "${pkgs.bash}/bin/bash" "-c" "echo hello > foo; cat foo" ]; }; }; # 13. example of running something as root on top of a parent image # Regression test related to PR #52109 runAsRootParentImage = buildImage { name = "runAsRootParentImage"; tag = "latest"; runAsRoot = "touch /example-file"; fromImage = bash; }; # 14. example of 3 layers images This image is used to verify the # order of layers is correct. # It allows to validate # - the layer of parent are below # - the order of parent layer is preserved at image build time # (this is why there are 3 images) layersOrder = let l1 = pkgs.dockerTools.buildImage { name = "l1"; tag = "latest"; extraCommands = '' mkdir -p tmp echo layer1 > tmp/layer1 echo layer1 > tmp/layer2 echo layer1 > tmp/layer3 ''; }; l2 = pkgs.dockerTools.buildImage { name = "l2"; fromImage = l1; tag = "latest"; extraCommands = '' mkdir -p tmp echo layer2 > tmp/layer2 echo layer2 > tmp/layer3 ''; }; in pkgs.dockerTools.buildImage { name = "l3"; fromImage = l2; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils ]; }; extraCommands = '' mkdir -p tmp echo layer3 > tmp/layer3 ''; }; # 15. Environment variable inheritance. # Child image should inherit parents environment variables, # optionally overriding them. environmentVariablesParent = pkgs.dockerTools.buildImage { name = "parent"; tag = "latest"; config = { Env = [ "FROM_PARENT=true" "LAST_LAYER=parent" ]; }; }; environmentVariables = pkgs.dockerTools.buildImage { name = "child"; fromImage = environmentVariablesParent; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils ]; }; config = { Env = [ "FROM_CHILD=true" "LAST_LAYER=child" ]; }; }; environmentVariablesLayered = pkgs.dockerTools.buildLayeredImage { name = "child"; fromImage = environmentVariablesParent; tag = "latest"; contents = [ pkgs.coreutils ]; config = { Env = [ "FROM_CHILD=true" "LAST_LAYER=child" ]; }; }; # 16. Create another layered image, for comparing layers with image 10. another-layered-image = pkgs.dockerTools.buildLayeredImage { name = "another-layered-image"; tag = "latest"; config.Cmd = [ "${pkgs.hello}/bin/hello" ]; }; # 17. Create a layered image with only 2 layers two-layered-image = pkgs.dockerTools.buildLayeredImage { name = "two-layered-image"; tag = "latest"; config.Cmd = [ "${pkgs.hello}/bin/hello" ]; contents = [ pkgs.bash pkgs.hello ]; maxLayers = 2; }; # 18. Create a layered image with more packages than max layers. # coreutils and hello are part of the same layer bulk-layer = pkgs.dockerTools.buildLayeredImage { name = "bulk-layer"; tag = "latest"; contents = with pkgs; [ coreutils hello ]; maxLayers = 2; }; # 19. Create a layered image with a base image and more packages than max # layers. coreutils and hello are part of the same layer layered-bulk-layer = pkgs.dockerTools.buildLayeredImage { name = "layered-bulk-layer"; tag = "latest"; fromImage = two-layered-image; contents = with pkgs; [ coreutils hello ]; maxLayers = 4; }; # 20. Create a "layered" image without nix store layers. This is not # recommended, but can be useful for base images in rare cases. no-store-paths = pkgs.dockerTools.buildLayeredImage { name = "no-store-paths"; tag = "latest"; extraCommands = '' # This removes sharing of busybox and is not recommended. We do this # to make the example suitable as a test case with working binaries. cp -r ${pkgs.pkgsStatic.busybox}/* . # This is a "build" dependency that will not appear in the image ${pkgs.hello}/bin/hello ''; }; nixLayered = pkgs.dockerTools.buildLayeredImageWithNixDb { name = "nix-layered"; tag = "latest"; contents = [ # nix-store uses cat program to display results as specified by # the image env variable NIX_PAGER. pkgs.coreutils pkgs.nix pkgs.bash ]; config = { Env = [ "NIX_PAGER=cat" # A user is required by nix # https://github.com/NixOS/nix/blob/9348f9291e5d9e4ba3c4347ea1b235640f54fd79/src/libutil/util.cc#L478 "USER=nobody" ]; }; }; # 21. Support files in the store on buildLayeredImage # See: https://github.com/NixOS/nixpkgs/pull/91084#issuecomment-653496223 filesInStore = pkgs.dockerTools.buildLayeredImageWithNixDb { name = "file-in-store"; tag = "latest"; contents = [ pkgs.coreutils pkgs.nix (pkgs.writeScriptBin "myscript" '' #!${pkgs.runtimeShell} cat ${pkgs.writeText "somefile" "some data"} '') ]; config = { Cmd = [ "myscript" ]; # For some reason 'nix-store --verify' requires this environment variable Env = [ "USER=root" ]; }; }; # 22. Ensure that setting created to now results in a date which # isn't the epoch + 1 for layered images. unstableDateLayered = pkgs.dockerTools.buildLayeredImage { name = "unstable-date-layered"; tag = "latest"; contents = [ pkgs.coreutils ]; created = "now"; }; # 23. Ensure that layers are unpacked in the correct order before the # runAsRoot script is executed. layersUnpackOrder = let layerOnTopOf = parent: layerName: pkgs.dockerTools.buildImage { name = "layers-unpack-order-${layerName}"; tag = "latest"; fromImage = parent; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ pkgs.coreutils ]; }; runAsRoot = '' #!${pkgs.runtimeShell} echo -n "${layerName}" >> /layer-order ''; }; # When executing the runAsRoot script when building layer C, if layer B is # not unpacked on top of layer A, the contents of /layer-order will not be # "ABC". layerA = layerOnTopOf null "a"; layerB = layerOnTopOf layerA "b"; layerC = layerOnTopOf layerB "c"; in layerC; # buildImage without explicit tag bashNoTag = pkgs.dockerTools.buildImage { name = "bash-no-tag"; # Not recommended. Use `buildEnv` between copy and packages to avoid file duplication. copyToRoot = pkgs.bashInteractive; }; # buildLayeredImage without explicit tag bashNoTagLayered = pkgs.dockerTools.buildLayeredImage { name = "bash-no-tag-layered"; contents = pkgs.bashInteractive; }; # buildImage without explicit tag bashNoTagStreamLayered = pkgs.dockerTools.streamLayeredImage { name = "bash-no-tag-stream-layered"; contents = pkgs.bashInteractive; }; # buildLayeredImage with non-root user bashLayeredWithUser = let nonRootShadowSetup = { user, uid, gid ? uid }: with pkgs; [ ( writeTextDir "etc/shadow" '' root:!x::::::: ${user}:!::::::: '' ) ( writeTextDir "etc/passwd" '' root:x:0:0::/root:${runtimeShell} ${user}:x:${toString uid}:${toString gid}::/home/${user}: '' ) ( writeTextDir "etc/group" '' root:x:0: ${user}:x:${toString gid}: '' ) ( writeTextDir "etc/gshadow" '' root:x:: ${user}:x:: '' ) ]; in pkgs.dockerTools.buildLayeredImage { name = "bash-layered-with-user"; tag = "latest"; contents = [ pkgs.bash pkgs.coreutils ] ++ nonRootShadowSetup { uid = 999; user = "somebody"; }; }; # basic example, with cross compilation cross = let # Cross compile for x86_64 if on aarch64 crossPkgs = if pkgs.stdenv.hostPlatform.system == "aarch64-linux" then pkgsCross.gnu64 else pkgsCross.aarch64-multiplatform; in crossPkgs.dockerTools.buildImage { name = "hello-cross"; tag = "latest"; copyToRoot = pkgs.buildEnv { name = "image-root"; pathsToLink = [ "/bin" ]; paths = [ crossPkgs.hello ]; }; }; # layered image where a store path is itself a symlink layeredStoreSymlink = let target = pkgs.writeTextDir "dir/target" "Content doesn't matter."; symlink = pkgs.runCommand "symlink" {} "ln -s ${target} $out"; in pkgs.dockerTools.buildLayeredImage { name = "layeredstoresymlink"; tag = "latest"; contents = [ pkgs.bash symlink ]; } // { passthru = { inherit symlink; }; }; # image with registry/ prefix prefixedImage = pkgs.dockerTools.buildImage { name = "registry-1.docker.io/image"; tag = "latest"; config.Cmd = [ "${pkgs.hello}/bin/hello" ]; }; # layered image with registry/ prefix prefixedLayeredImage = pkgs.dockerTools.buildLayeredImage { name = "registry-1.docker.io/layered-image"; tag = "latest"; config.Cmd = [ "${pkgs.hello}/bin/hello" ]; }; # layered image with files owned by a user other than root layeredImageWithFakeRootCommands = pkgs.dockerTools.buildLayeredImage { name = "layered-image-with-fake-root-commands"; tag = "latest"; contents = [ pkgs.pkgsStatic.busybox ]; fakeRootCommands = '' mkdir -p ./home/alice chown 1000 ./home/alice ln -s ${pkgs.hello.overrideAttrs (o: { # A unique `hello` to make sure that it isn't included via another mechanism by accident. configureFlags = o.configureFlags or [] ++ [ " --program-prefix=layeredImageWithFakeRootCommands-" ]; doCheck = false; })} ./hello ''; }; # tarball consisting of both bash and redis images mergedBashAndRedis = pkgs.dockerTools.mergeImages [ bash redis ]; # tarball consisting of bash (without tag) and redis images mergedBashNoTagAndRedis = pkgs.dockerTools.mergeImages [ bashNoTag redis ]; # tarball consisting of bash and layered image with different owner of the # /home/alice directory mergedBashFakeRoot = pkgs.dockerTools.mergeImages [ bash layeredImageWithFakeRootCommands ]; helloOnRoot = pkgs.dockerTools.streamLayeredImage { name = "hello"; tag = "latest"; contents = [ (pkgs.buildEnv { name = "hello-root"; paths = [ pkgs.hello ]; }) ]; config.Cmd = [ "hello" ]; }; helloOnRootNoStore = pkgs.dockerTools.streamLayeredImage { name = "hello"; tag = "latest"; contents = [ (pkgs.buildEnv { name = "hello-root"; paths = [ pkgs.hello ]; }) ]; config.Cmd = [ "hello" ]; includeStorePaths = false; }; etc = let inherit (pkgs) lib; nixosCore = (evalMinimalConfig ({ config, ... }: { imports = [ pkgs.pkgsModule ../../../nixos/modules/system/etc/etc.nix ]; environment.etc."some-config-file" = { text = '' 127.0.0.1 localhost ::1 localhost ''; # For executables: # mode = "0755"; }; })); in pkgs.dockerTools.streamLayeredImage { name = "etc"; tag = "latest"; enableFakechroot = true; fakeRootCommands = '' mkdir -p /etc ${nixosCore.config.system.build.etcActivationCommands} ''; config.Cmd = pkgs.writeScript "etc-cmd" '' #!${pkgs.busybox}/bin/sh ${pkgs.busybox}/bin/cat /etc/some-config-file ''; }; # Example export of the bash image exportBash = pkgs.dockerTools.exportImage { fromImage = bash; }; imageViaFakeChroot = pkgs.dockerTools.streamLayeredImage { name = "image-via-fake-chroot"; tag = "latest"; config.Cmd = [ "hello" ]; enableFakechroot = true; # Crucially, instead of a relative path, this creates /bin, which is # intercepted by fakechroot. # This functionality is not available on darwin as of 2021. fakeRootCommands = '' mkdir /bin ln -s ${pkgs.hello}/bin/hello /bin/hello ''; }; build-image-with-path = buildImage { name = "build-image-with-path"; tag = "latest"; # Not recommended. Use `buildEnv` between copy and packages to avoid file duplication. copyToRoot = [ pkgs.bashInteractive ./test-dummy ]; }; layered-image-with-path = pkgs.dockerTools.streamLayeredImage { name = "layered-image-with-path"; tag = "latest"; contents = [ pkgs.bashInteractive ./test-dummy ]; }; }