7.3 The Docker recipes

Read the tutorial. Build it yourself is the other way to read this part.

This walk goes through rahuldave/cheesecracker on GitHub. This part starts from the code at 0acb4556f724, partway through step-07. The code before this part

To look at this code on your machine, run these commands. The first one makes a clone, if this folder has none:

[ -d cheesecracker ] || git clone https://github.com/rahuldave/cheesecracker
cd cheesecracker
git fetch --quiet --tags --force origin
git switch --detach 0acb4556f724

just setup

Docker packs the server, with Python and its packages, into an image. It builds the image from a file called Dockerfile, and runs it as a container, a process kept apart from the rest of the machine. The whole tutorial then writes .dockerignore, and a Dockerfile that makes the run image, the image that runs the server. Three recipes build an image, start its server and stop it.

7.3 just docker-build, just docker-serve and just docker-stop

Three recipes give the Docker commands short names. docker-build builds an image of the Dockerfile. docker-serve starts the server of the run image in the background, at port 9000, and docker-stop stops it.

± See the change to justfile

The recipe docker-build takes the name of a stage, and runs docker build --target with it. docker-serve runs the image cheesecracker-run with --detach, so the container runs in the background, as in the original tutorial's docker run -d. --publish connects its port 9000 to port 9000 of this machine. The recipe then asks /health until the server answers. docker-stop stops the container, and --rm removes it.

just docker-build run

Docker takes each layer that has not changed since the last build from its cache, and prints CACHED for it.

just docker-serve

The recipe prints docker-serve: http://localhost:9000, in the container cheesecracker-run. Ask the server for its health.

curl -s localhost:9000/health

The server in Docker answers {"status":"healthy"}, as the server on this machine did. The container runs in the background, so you do not see what it prints. Docker keeps that output, and docker logs shows it.

docker logs cheesecracker-run

uvicorn printed Uvicorn running on http://0.0.0.0:9000, and started four server processes, its workers.

just docker-stop

Docker prints the name of the container, cheesecracker-run, and the server stops.

What changed

justfile: the recipes docker-build, docker-serve and docker-stop. 20 lines added. The file
- look at docker run --rm --detach --name cheesecracker-run --publish 9000:9000 cheesecracker-run > /dev/null || exit 1

The diff of justfile

@@ -62,3 +62,23 @@ check:
     just fmt --check
     just lint
     just test -q
+
+# Build an image of the Dockerfile: just docker-build run
+docker-build kind:
+    docker build --target "$1" --tag "cheesecracker-$1" .
+
+# Start the server in the run image, in the background, at http://localhost:9000, as it runs in production. just docker-stop stops it
+docker-serve:
+    #!/usr/bin/env sh
+    if curl -sf localhost:9000/health > /dev/null; then echo "docker-serve: a server already answers at http://localhost:9000" >&2; exit 1; fi
+    docker run --rm --detach --name cheesecracker-run --publish 9000:9000 cheesecracker-run > /dev/null || exit 1
+    for i in $(seq 1 30); do
+        if curl -sf localhost:9000/health > /dev/null; then echo "docker-serve: http://localhost:9000, in the container cheesecracker-run"; exit 0; fi
+        sleep 1
+    done
+    echo "docker-serve: no answer after 30 seconds; read docker logs cheesecracker-run" >&2
+    exit 1
+
+# Stop the server of just docker-serve, and remove its container
+docker-stop:
+    docker stop cheesecracker-run

This change on GitHub

This part ends at the code at step-07. The code after this part