diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..e6eacbd
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,3 @@
+.git
+.direnv
+result/
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 83d583a..10e978f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -46,52 +46,29 @@ jobs:
         env:
           PYTHON: ${{ matrix.python }}
         run: |
+          nix build .#checks.x86_64-linux.pre-commit
+          nix build .#devShells.x86_64-linux.default-$(echo $PYTHON)
+          nix build .#packages.x86_64-linux.default-$(echo $PYTHON)
           nix build .#checks.x86_64-linux.tests-$(echo $PYTHON)
-          nix build .#packages.x86_64-linux.impure-check-$(echo $PYTHON)
 
   impure_tests:
     name: Impure Tests
 
-    strategy:
-      matrix:
-        python-version: ["3.9", "3.10", "3.11"]
-
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
 
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - name: Install Poetry
-        uses: snok/install-poetry@v1
-
+      - name: Build Docker image with nix env for tesh development
+        run: docker build -t tesh .
 
-      - name: Install Poetry environment
-        env:
-          PYTHON: python${{ matrix.python-version }}
-        run: |
-          poetry env use $PYTHON
-          poetry install
-
-      - name: Install test dependencies
-        run: sudo apt-get -y install nmap
+      - name: Start a container
+        run: docker run -d --rm -v .:/tesh --name tesh -it tesh
 
-      - name: Run linters and unit tests the Poetry way
-        run: |
-          # make lint -> pre-commit-config.yaml is managed by Nix,
-          # so path entries won't work in Poetry env
-          source $(poetry env info --path)/bin/activate
-          make types
-          make unit
-          make tesh
-
-      - uses: cachix/install-nix-action@v22
+      - name: Make git happy so that pre-commit checks in `make lint` work
+        run: docker exec tesh git config --global --add safe.directory /tesh
 
-      - name: Run 'make examples'
-        run: poetry run tesh examples/
+      - name: Run all tests
+        run: docker exec tesh nix develop -c make tests
 
   release:
     name: Release
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..e57f127
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,9 @@
+FROM ubuntu:23.10
+RUN apt-get update \
+    && apt-get install nano git nix -y \
+    && echo "experimental-features = nix-command flakes" >> /etc/nix/nix.conf \
+    && echo "max-jobs = 4" >> /etc/nix/nix.conf
+COPY ./. /tesh
+RUN nix develop /tesh -c true
+WORKDIR /tesh
+CMD nix develop
diff --git a/Makefile b/Makefile
index bdb4580..7bd891e 100644
--- a/Makefile
+++ b/Makefile
@@ -66,10 +66,6 @@ endif
 tesh:
 	@tesh *.md
 
-.PHONY: examples
-examples:
-	@tesh examples/
-
 .PHONY: test
 test: tests
 
@@ -79,4 +75,3 @@ tests:
 	@make types
 	@make unit
 	@make tesh
-	@make examples
diff --git a/README.md b/README.md
index 4ffd02d..79d06b0 100644
--- a/README.md
+++ b/README.md
@@ -275,13 +275,11 @@ $ pip install tesh
 
 ## Developing `tesh`
 
-We provide two development environments for people working on this project, one based on [Nix](https://nixos.org/) and one based on [Poetry](https://www.docker.com/).
+We provide two development environments for people working on this project, one based on [Nix](https://nixos.org/) and one based on [Docker](https://www.docker.com/).
 
 For Nix, run `nix develop` to enter the development environment, where everything is ready for use.
 
-For Poetry, run the following:
-* `poetry install` to prepare the Python development environment
-* `pre-commit install --config .pre-commit-config.impure.yaml`
+For Docker, run `docker build -t tesh . && docker run --rm -v .:/tesh -it tesh` to enter the development environment, where everything is ready for use.
 
 Then you can run `make tests` to run all tests & checks.
 
@@ -326,4 +324,9 @@ $ nix develop .#devShells.aarch64-darwin.default-python39
 
 # TODO:
 
+* rename packages, so they are not default-python310, etc.
 * docker image
+* commands instead of docker actions
+
+
+* docker build .
diff --git a/examples/nix-shell.md b/examples/nix-shell.md
deleted file mode 100644
index 6521494..0000000
--- a/examples/nix-shell.md
+++ /dev/null
@@ -1,15 +0,0 @@
-# `nix-shell` example
-
-```console tesh-session="nix-shell" tesh-ps1="[nix-shell:~]$" tesh-timeout="60"
-$ echo $IN_NIX_SHELL
-$ export NIX_PATH=nixpkgs=https://github.com/nixos/nixpkgs/archive/c7a18f89ef1dc423f57f3de9bd5d9355550a5d15.tar.gz
-$ nix-shell -p hello
-...
-[nix-shell:~]$ echo $IN_NIX_SHELL
-impure
-[nix-shell:~]$ which hello
-/nix/store/...-hello-.../bin/hello
-[nix-shell:~]$ exit
-exit
-$
-```
diff --git a/flake.nix b/flake.nix
index a0d4364..a61a69b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -20,7 +20,7 @@
       imports = [
         inputs.pre-commit-hooks-nix.flakeModule
       ];
-      systems = [ "x86_64-linux" "aarch64-darwin" ];
+      systems = [ "x86_64-linux" "aarch64-darwin" "aarch64-linux" ];
       perSystem = { config, self', inputs', pkgs, system, lib, ... }:
 
         let
@@ -36,6 +36,21 @@
                 (python: f python);
             in
             lib.mapAttrs' (py: value: { name = "${name}-${py}"; inherit value; }) outputs;
+
+          poetryArgs = python: {
+            projectDir = ./.;
+            preferWheels = true;
+            python = pkgs.${python};
+            overrides = inputs'.poetry2nix.legacyPackages.overrides.withDefaults (self: super: {
+
+              ruamel-yaml-clib = super.ruamel-yaml-clib.override (
+                old: {
+                  preferWheel = false;
+                }
+              );
+            });
+          };
+
         in
         {
           # Per-system attributes can be defined here. The self' and inputs'
@@ -89,47 +104,15 @@
 
           packages =
             (forAllPythons "default" (python:
-              inputs.poetry2nix.legacyPackages.${system}.mkPoetryApplication {
-                projectDir = ./.;
-                preferWheels = true;
-                python = pkgs.${python};
-              }))
+              inputs.poetry2nix.legacyPackages.${system}.mkPoetryApplication (poetryArgs python)))
 
             //
 
             (forAllPythons "testEnv" (python:
-              inputs.poetry2nix.legacyPackages.${system}.mkPoetryEnv {
-                projectDir = ./.;
-                preferWheels = true;
-                python = pkgs.${python};
-              }))
+              inputs.poetry2nix.legacyPackages.${system}.mkPoetryEnv (poetryArgs python)));
 
-            //
-
-            (forAllPythons "impure-check" (python:
-              pkgs.writeScriptBin "impure-check" ''
-                # run the impure-check in a temp dir that gets nuked
-                # if this script fails in any way
-                export TMPDIR=$(${pkgs.coreutils}/bin/mktemp -d)
-                trap "${pkgs.coreutils}/bin/chmod -R +w '$TMPDIR'; ${pkgs.coreutils}/bin/rm -rf '$TMPDIR'" EXIT
-
-                export PATH="${lib.makeBinPath [
-                  pkgs.coreutils
-                  pkgs.gnumake
-                  pkgs.bash
-                  pkgs.nix
-                  pkgs.which
-                  self'.packages."default-${python}"
-                ]}"
-
-                cd $TMPDIR
-                cp -r ${./.}/* ./
-                make examples
-              ''
-            ));
-
-          # 'make lint' not needed since pre-commit is run by pre-commit flake-part
-          # 'make examples' is an impure test so it's done in `impure-check`
+          # `make unit` is not needed as it's already run in pre-commit
+          # check, registered by flake-parts
           checks =
             (forAllPythons "tests" (python:
               pkgs.runCommand "tests"
@@ -147,7 +130,7 @@
               ''));
 
           devShells =
-            {default=self'.devShells.default-python311;}
+            { default = self'.devShells.default-python311; }
 
             //
 
@@ -157,41 +140,41 @@
               in
 
               pkgs.mkShell
-              {
-                name = "dev-shell";
+                {
+                  name = "dev-shell";
 
-                buildInputs = with pkgs; [
-                  poetry
-                  self'.packages."testEnv-${python}"
+                  buildInputs = with pkgs; [
+                    poetry
+                    self'.packages."testEnv-${python}"
 
-                  # test dependency
-                  nmap
-                ];
+                    # test dependency
+                    nmap
+                  ];
 
-                inputsFrom = [ config.pre-commit.devShell ];
+                  inputsFrom = [ config.pre-commit.devShell ];
 
-                shellHook = ''
-                  tmp_path=$(realpath ./.direnv)
+                  shellHook = ''
+                    tmp_path=$(realpath ./.direnv)
 
-                  source=$(realpath .)
-                  mkdir -p "$tmp_path/python/${testEnv.sitePackages}"
+                    source=$(realpath .)
+                    mkdir -p "$tmp_path/python/${testEnv.sitePackages}"
 
-                  # Install the package in editable mode
-                  # This allows executing `clan` from within the dev-shell using the current
-                  # version of the code and its dependencies.
-                  PYTHONPATH=${pkgs."python${lib.replaceStrings ["python"] [""] python}Packages".poetry-core}/${testEnv.sitePackages}:${testEnv}/${testEnv.sitePackages} ${pkgs."python${lib.replaceStrings ["python"] [""] python}Packages".pip}/bin/pip install \
-                    --no-deps \
-                    --disable-pip-version-check \
-                    --no-index \
-                    --no-build-isolation \
-                    --prefix "$tmp_path/python" \
-                    --editable $source
+                    # Install the package in editable mode
+                    # This allows executing `clan` from within the dev-shell using the current
+                    # version of the code and its dependencies.
+                    PYTHONPATH=${pkgs."python${lib.replaceStrings ["python"] [""] python}Packages".poetry-core}/${testEnv.sitePackages}:${testEnv}/${testEnv.sitePackages} ${pkgs."python${lib.replaceStrings ["python"] [""] python}Packages".pip}/bin/pip install \
+                      --no-deps \
+                      --disable-pip-version-check \
+                      --no-index \
+                      --no-build-isolation \
+                      --prefix "$tmp_path/python" \
+                      --editable $source
 
-                  export PATH="$tmp_path/python/bin:$PATH"
-                  export PYTHONPATH="$source/src:$tmp_path/python/${testEnv.sitePackages}:${testEnv}/${testEnv.sitePackages}"
-                '';
+                    export PATH="$tmp_path/python/bin:$PATH"
+                    export PYTHONPATH="$source/src:$tmp_path/python/${testEnv.sitePackages}:${testEnv}/${testEnv.sitePackages}"
+                  '';
 
-            }));
+                }));
         };
     };
 }