delegate Python deps management to Python deps manager (#127)

This should make it easier to add/play with Sphinx extensions moving
forward.

This still uses direnv to:
- Load the Nix environment.
- Load the Python virtualenv environment.
- Ensure that any change to `requirements.txt` is immediately reflected
  (on next CLI prompt).

This still uses Nix to:
- Install appropriate versions of curl, AWS CLI, git, jq, imagemagick,
  and TeX (along with all of the required TeX packages).
- Install Python itself, so we know we're all using the same one.

Author: garyverhaegen-da

.circleci/config.yml

@@ -50,6 +50,23 @@ commands:
         - /home/circleci/.nix-channels
         - /home/circleci/.nix-defexpr
         - /home/circleci/.config/nix
+  setup_python:
+    description: Set up Python
+    steps:
+    - run:
+        name: setup_python
+        command: |
+          set -euo pipefail
+          . /home/circleci/.nix-profile/etc/profile.d/nix.sh
+          nix-shell shell.nix \
+            --pure \
+            --run bash \<<'EOF'
+            set -euo pipefail
+
+            python3 -m venv .python-env
+            source .python-env/bin/activate
+            python -m pip install -r requirements.txt
+          EOF
 
 jobs:
   build_docs:
@@ -60,11 +77,11 @@ jobs:
     steps:
       - checkout
       - setup_nix
+      - setup_python
       - run:
          name: build
          command: |
            set -euo pipefail
-
            . /home/circleci/.nix-profile/etc/profile.d/nix.sh
 
            mkdir -p /tmp/workspace
@@ -75,6 +92,8 @@ jobs:
              --keep ARTIFACTORY_PASSWORD \
              --run bash \<<'EOF'
              set -euo pipefail
+             source .python-env/bin/activate
+             PATH="$(pwd)/.python-env/bin:$PATH"
              prefix=$(jq -r '.prefix' versions.json)
              if [[ ${#prefix} -lt 5 ]]; then
                echo "Pushhing to $prefix is not currently supported."
@@ -135,6 +154,7 @@ jobs:
     steps:
       - checkout
       - setup_nix
+      - setup_python
       - run:
          name: push
          command: |
@@ -150,6 +170,8 @@ jobs:
              --keep AWS_SECRET_ACCESS_KEY \
              --run bash \<<'EOF'
              set -euo pipefail
+             source .python-env/bin/activate
+             PATH="$(pwd)/.python-env/bin:$PATH"
 
              snapshots=$(curl -sf https://docs.daml.com/snapshots.json \
                         | jq -r '

.envrc

@@ -2,4 +2,17 @@ use nix
 
 PATH_add bin
 
+pyenv=.python-env
+
+if ! [ -d $pyenv ]; then
+    python3 -m venv $pyenv
+fi
+
+source $pyenv/bin/activate
+PATH_add $pyenv/bin
+
+python -m pip install -r requirements.txt
+
 [[ -f .envrc.private ]] && source_env .envrc.private
+
+watch_file requirements.txt

.gitignore

@@ -1,4 +1,6 @@
 .envrc.private
 .DS_Store
 
+.python-env
+
 workdir/