Devcontainer config for developing in codespaces

Author: chriscarrollsmith

.devcontainer/devcontainer.json

@@ -0,0 +1,36 @@
+{
+  "name": "FastAPI Jinja2 Postgres WebApp",
+  "workspaceFolder": "/workspaces/fastapi-jinja2-postgres-webapp",
+
+  // Ensure .env exists before Docker Compose processes env_file entries
+  "initializeCommand": "bash .devcontainer/ensure-env.sh",
+
+  // Start the Postgres sidecar using the existing compose file
+  "dockerComposeFile": [
+    "../docker-compose.yml",
+    "docker-compose.yml"
+  ],
+  "service": "app",
+  "runServices": ["db"],
+  "shutdownAction": "stopCompose",
+
+  // Forward common app/db ports
+  "forwardPorts": [8000, 5432],
+  "portsAttributes": {
+    "8000": { "label": "FastAPI", "onAutoForward": "openBrowser" },
+    "5432": { "label": "PostgreSQL" }
+  },
+
+  // Prepare env, install uv, and sync deps
+  "postCreateCommand": "bash .devcontainer/init-env.sh && curl -LsSf https://astral.sh/uv/install.sh | sh && ~/.local/bin/uv sync",
+
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-python.python",
+        "ms-python.vscode-pylance"
+      ]
+    }
+  }
+}
+

.devcontainer/docker-compose.yml

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+services:
+  app:
+    image: mcr.microsoft.com/devcontainers/python:3.13-bookworm
+    container_name: fastapi-jinja2-postgres-webapp-app
+    volumes:
+      - ..:/workspaces/fastapi-jinja2-postgres-webapp:cached
+    working_dir: /workspaces/fastapi-jinja2-postgres-webapp
+    depends_on:
+      - db
+    env_file:
+      - ../.env
+    command: sleep infinity
+
+  # Override/augment settings for the db service defined in the root compose file
+  db:
+    # Avoid requiring a project-level .env during compose evaluation
+    env_file: []
+    environment:
+      POSTGRES_USER: ${DB_USER:-postgres}
+      POSTGRES_PASSWORD: ${DB_PASSWORD:-postgres}
+      POSTGRES_DB: ${DB_NAME:-fastapi-jinja2-postgres-webapp}
+    ports:
+      - "5432:5432"
+
+# Note: The 'db' service is defined in the repository root docker-compose.yml.
+# This file is merged with that one via devcontainer.json dockerComposeFile array.
+

.devcontainer/ensure-env.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Run from repo root
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
+# Ensure a .env exists BEFORE docker compose evaluates env_file
+if [ ! -f ".env" ]; then
+  if [ -f ".env.example" ]; then
+    cp .env.example .env || true
+  else
+    touch .env
+  fi
+fi
+
+echo ".env ensured for compose evaluation."
+

.devcontainer/init-env.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Run from repo root
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
+# Ensure a working .env exists
+if [ ! -f ".env" ]; then
+  if [ -f ".env.example" ]; then
+    cp .env.example .env || true
+  else
+    touch .env
+  fi
+fi
+
+# Ensure DB_HOST points to the compose service name for in-container access
+if grep -q '^DB_HOST=' .env; then
+  sed -i 's/^DB_HOST=.*/DB_HOST=db/' .env
+else
+  echo 'DB_HOST=db' >> .env
+fi
+
+generate_secret() {
+  if command -v openssl >/dev/null 2>&1; then
+    openssl rand -base64 32
+  else
+    python - <<'PY'
+import base64, os
+print(base64.b64encode(os.urandom(32)).decode('ascii'))
+PY
+  fi
+}
+
+# Ensure SECRET_KEY exists and is non-empty/non-placeholder
+if grep -q '^SECRET_KEY=' .env; then
+  current_secret="$(grep '^SECRET_KEY=' .env | cut -d= -f2-)"
+  if [ -z "${current_secret}" ] || [ "${current_secret}" = "changeme" ] || [ "${current_secret}" = "REPLACE_ME" ]; then
+    new_secret="$(generate_secret)"
+    sed -i "s/^SECRET_KEY=.*/SECRET_KEY=${new_secret}/" .env
+  fi
+else
+  echo "SECRET_KEY=$(generate_secret)" >> .env
+fi
+
+echo "Environment prepared. DB_HOST set to 'db' and SECRET_KEY ensured."
+

.gitignore

@@ -1,4 +1,3 @@
-.devcontainer
 __pycache__
 *.pyc
 .env