From ec552567c7c3e4719e3b3664e78dc12f5d72486a Mon Sep 17 00:00:00 2001
From: Milas Bowman <milas.bowman@docker.com>
Date: Fri, 8 Jul 2022 09:22:59 -0400
Subject: [PATCH] flask: dev envs support & misc improvements (#263)

* Docker Desktop Development Environments config
* Use cache volumes for pip
* Upgrade from Python 3.7 -> Python 3.10
* Use port `8000` to avoid conflicts with Airplay on
  macOS for default Flask port `5000`
* Use `SIGINT` to gracefully stop Flask

Signed-off-by: Milas Bowman <milas.bowman@docker.com>
---
 flask/.docker/docker-compose.yaml | 10 ++++++++
 flask/README.md                   | 42 ++++++++++++++++++++-----------
 flask/app/Dockerfile              | 30 ++++++++++++++++++----
 flask/app/app.py                  |  2 +-
 flask/compose.yaml                | 11 +++++---
 5 files changed, 71 insertions(+), 24 deletions(-)
 create mode 100644 flask/.docker/docker-compose.yaml

diff --git a/flask/.docker/docker-compose.yaml b/flask/.docker/docker-compose.yaml
new file mode 100644
index 0000000..8e9e1b2
--- /dev/null
+++ b/flask/.docker/docker-compose.yaml
@@ -0,0 +1,10 @@
+services:
+  web: 
+    build:
+      context: app
+      target: dev-envs
+    stop_signal: SIGINT
+    ports: 
+      - '8000:8000'
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
diff --git a/flask/README.md b/flask/README.md
index d97eb65..36e78d5 100644
--- a/flask/README.md
+++ b/flask/README.md
@@ -16,37 +16,38 @@ Project structure:
 ```
 services: 
   web: 
-    build: app 
+    build:
+     context: app
+     target: builder
     ports: 
-      - '5000:5000'
+      - '8000:8000'
 ```
 
 ## Deploy with docker compose
 
 ```
 $ docker compose up -d
-Creating network "flask_default" with the default driver
-Building web
-Step 1/6 : FROM python:3.7-alpine
-...
-...
-Status: Downloaded newer image for python:3.7-alpine
-Creating flask_web_1 ... done
-
+[+] Building 1.1s (16/16) FINISHED
+ => [internal] load build definition from Dockerfile                                                                                                                                                                                       0.0s
+    ...                                                                                                                                         0.0s
+ => => naming to docker.io/library/flask_web                                                                                                                                                                                               0.0s
+[+] Running 2/2
+ ⠿ Network flask_default  Created                                                                                                                                                                                                          0.0s
+ ⠿ Container flask-web-1  Started
 ```
 
 ## Expected result
 
 Listing containers must show one container running and the port mapping as below:
 ```
-$ docker ps
-CONTAINER ID        IMAGE                        COMMAND                  CREATED             STATUS              PORTS                  NAMES
-c126411df522        flask_web                    "python3 app.py"         About a minute ago  Up About a minute   0.0.0.0:5000->5000/tcp flask_web_1
+$ docker compose ps
+NAME                COMMAND             SERVICE             STATUS              PORTS
+flask-web-1         "python3 app.py"    web                 running             0.0.0.0:8000->8000/tcp
 ```
 
-After the application starts, navigate to `http://localhost:5000` in your web browser or run:
+After the application starts, navigate to `http://localhost:8000` in your web browser or run:
 ```
-$ curl localhost:5000
+$ curl localhost:8000
 Hello World!
 ```
 
@@ -54,3 +55,14 @@ Stop and remove the containers
 ```
 $ docker compose down
 ```
+
+## Use with Docker Development Environments
+
+You can use this sample with the Dev Environments feature of Docker Desktop.
+
+![Screenshot of creating a Dev Environment in Docker Desktop](../dev-envs.png)
+
+To develop directly on the services inside containers, use the HTTPS Git url of the sample:
+```
+https://github.com/docker/awesome-compose/tree/master/flask
+```
diff --git a/flask/app/Dockerfile b/flask/app/Dockerfile
index cf861e9..d0be3b5 100644
--- a/flask/app/Dockerfile
+++ b/flask/app/Dockerfile
@@ -1,7 +1,27 @@
-FROM python:3.7-alpine 
-WORKDIR /app 
+# syntax=docker/dockerfile:1.4
+FROM --platform=$BUILDPLATFORM python:3.10-alpine AS builder
+
+WORKDIR /app
+
 COPY requirements.txt /app
-RUN pip3 install -r requirements.txt --no-cache-dir
-COPY . /app 
-ENTRYPOINT ["python3"] 
+RUN --mount=type=cache,target=/root/.cache/pip \
+    pip3 install -r requirements.txt
+
+COPY . /app
+
+ENTRYPOINT ["python3"]
 CMD ["app.py"]
+
+FROM builder as dev-envs
+
+RUN <<EOF
+apk update
+apk add git
+EOF
+
+RUN <<EOF
+addgroup -S docker
+adduser -S --shell /bin/bash --ingroup docker vscode
+EOF
+# install Docker tools (cli, buildx, compose)
+COPY --from=gloursdocker/docker / /
diff --git a/flask/app/app.py b/flask/app/app.py
index e511196..b29672a 100644
--- a/flask/app/app.py
+++ b/flask/app/app.py
@@ -6,4 +6,4 @@ def hello():
 	return "Hello World!"
 
 if __name__ == '__main__':
-	app.run(host='0.0.0.0')
+	app.run(host='0.0.0.0', port=8000)
diff --git a/flask/compose.yaml b/flask/compose.yaml
index 830c446..a6a8672 100644
--- a/flask/compose.yaml
+++ b/flask/compose.yaml
@@ -1,5 +1,10 @@
 services:
   web: 
-    build: app 
-    ports: 
-      - '5000:5000'
+    build:
+      context: app
+      target: builder
+    # flask requires SIGINT to stop gracefully
+    # (default stop signal from Compose is SIGTERM)
+    stop_signal: SIGINT
+    ports:
+      - '8000:8000'