diff --git a/.github/workflows/direnv.yml b/.github/workflows/direnv.yml
new file mode 100644
index 00000000..96c85f75
--- /dev/null
+++ b/.github/workflows/direnv.yml
@@ -0,0 +1,45 @@
+name: direnv
+on:
+  push:
+    paths:
+      - programs/direnv/install.bash
+      - .github/workflows/direnv.yml
+  schedule:
+    # Not at the start of an hour or a day to decreate the chance of delay.
+    # See schedule documentation.
+    # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule
+    - cron: "17 5 * * *"
+
+  workflow_dispatch:
+
+jobs:
+  test_idempotent_installation:
+
+    strategy:
+      matrix:
+        os:
+          - "ubuntu:20.04"
+          - "ubuntu:22.04"
+
+    runs-on: ubuntu-latest
+    container:
+      image: "${{ matrix.os }}"
+
+    steps:
+
+      - name: Check out code
+        uses: actions/checkout@v3
+
+      - name: Prepare Docker
+        run: ./scripts/prepare_docker.bash
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install direnv
+        shell: su norm --command "bash --login {0}"
+        run: programs/direnv/install.bash
+
+      - name: Install direnv again (test idempotency)
+        shell: su norm --command "bash --login {0}"
+        run: programs/direnv/install.bash
+
diff --git a/programs/direnv/install.bash b/programs/direnv/install.bash
new file mode 100755
index 00000000..89a2dd73
--- /dev/null
+++ b/programs/direnv/install.bash
@@ -0,0 +1,35 @@
+#!/bin/bash
+
+# Name: direnv
+# https://github.com/direnv/direnv
+
+set -euxo pipefail
+
+cd "$(mktemp --dir)"
+
+sudo apt-get update
+
+sudo apt-get --assume-yes install \
+curl \
+jq
+
+browser_download_url=$(
+  curl -Ss 'https://api.github.com/repos/direnv/direnv/releases/latest' |
+  jq -r '.assets[] | select(.name == "direnv.linux-amd64") | .browser_download_url'
+)
+
+download_filename=$(
+  curl \
+  --silent \
+  --show-error \
+  --url "$browser_download_url" \
+  --location \
+  --remote-name \
+  --write-out '%{filename_effective}'
+)
+
+chmod +x "${download_filename}"
+
+sudo mv "${download_filename}" /usr/local/bin/direnv
+
+direnv --version