Gitpod configuration.

Adapted from https://github.com/gitpod-io/template-nix.

.gitignore

@@ -34,4 +34,5 @@ doc/*.pyg
 doc/movies/snippets/
 doc/movies/targets.mk
 __pycache__
-alectryon-html/
+alectryon-html/
+.envrc

.gitpod.yml

@@ -0,0 +1,14 @@
+image:
+  file: .nix/gitpod.Dockerfile
+tasks:
+  - init: >
+      mkdir -p /home/gitpod/.config/nix &&
+      echo 'sandbox = false' >> /home/gitpod/.config/nix/nix.conf &&
+      echo 'use nix' > .envrc &&
+      direnv allow .
+
+vscode:
+  extensions:
+    - bbenoist.Nix
+    - maximedenes.vscoq
+    - cab404.vscode-direnv

.nix/gitpod.Dockerfile

@@ -0,0 +1,58 @@
+# MIT License
+
+# Copyright (c) 2021 Gitpod
+
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+FROM gitpod/workspace-base
+
+USER root
+
+# Install Nix
+RUN addgroup --system nixbld \
+  && adduser gitpod nixbld \
+  && for i in $(seq 1 30); do useradd -ms /bin/bash nixbld$i &&  adduser nixbld$i nixbld; done \
+  && mkdir -m 0755 /nix && chown gitpod /nix \
+  && mkdir -p /etc/nix && echo 'sandbox = false' > /etc/nix/nix.conf
+
+# Install Nix
+CMD /bin/bash -l
+USER gitpod
+ENV USER gitpod
+WORKDIR /home/gitpod
+
+RUN touch .bash_profile \
+ && curl https://nixos.org/releases/nix/nix-2.3.14/install | sh
+
+RUN echo '. /home/gitpod/.nix-profile/etc/profile.d/nix.sh' >> /home/gitpod/.bashrc
+RUN mkdir -p /home/gitpod/.config/nixpkgs && echo '{ allowUnfree = true; }' >> /home/gitpod/.config/nixpkgs/config.nix
+
+# Install cachix
+RUN . /home/gitpod/.nix-profile/etc/profile.d/nix.sh \
+  && nix-env -iA cachix -f https://cachix.org/api/v1/install \
+  && cachix use cachix
+
+# Install git
+RUN . /home/gitpod/.nix-profile/etc/profile.d/nix.sh \
+  && nix-env -i git git-lfs
+
+# Install direnv
+RUN . /home/gitpod/.nix-profile/etc/profile.d/nix.sh \
+  && nix-env -i direnv \
+  && direnv hook bash >> /home/gitpod/.bashrc