docs: add fastapi tutorial spread test

docs/tutorial/code/fastapi/app.py

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+from fastapi import FastAPI
+
+app = FastAPI()
+
+@app.get("/")
+async def root():
+    return {"message": "Hello World"}

docs/tutorial/code/fastapi/greeting_app.py

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+import os
+
+from fastapi import FastAPI
+
+app = FastAPI()
+
+@app.get("/")
+async def root():
+    return {"message": os.getenv("APP_GREETING", "Hello World")}

docs/tutorial/code/fastapi/greeting_charmcraft.yaml

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+# configuration snippet for FastAPI application with a configuration
+
+config:
+  options:
+    greeting:
+      description: |
+        The greeting to be returned by the FastAPI application.
+      default: "Hello, world!"
+      type: string

docs/tutorial/code/fastapi/requirements.txt

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+fastapi[standard]
+psycopg2-binary

docs/tutorial/code/fastapi/task.yaml

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+###########################################
+# IMPORTANT
+# Comments matter!
+# The docs use the wrapping comments as
+# markers for including said instructions
+# as snippets in the docs.
+###########################################
+summary: Getting started with FastAPI tutorial
+
+kill-timeout: 180m
+
+environment:
+
+execute: |
+  # Move everything to $HOME so that Juju deployment works
+  mv *.yaml *.py *.txt $HOME
+  cd $HOME
+
+  # Don't use the staging store for this test
+  unset CHARMCRAFT_STORE_API_URL
+  unset CHARMCRAFT_UPLOAD_URL
+  unset CHARMCRAFT_REGISTRY_URL
+
+  # MicroK8s config setup
+  microk8s status --wait-ready
+  microk8s enable hostpath-storage
+  microk8s enable registry
+  microk8s enable ingress
+
+  # Bootstrap controller
+  juju bootstrap microk8s dev-controller
+
+  # [docs:create-venv]
+  sudo apt-get update && sudo apt-get install python3-venv -y
+  python3 -m venv .venv
+  source .venv/bin/activate
+  # [docs:create-venv-end]
+
+  # [docs:install-requirements]
+  pip install -r requirements.txt
+  # [docs:install-requirements-end]
+
+  fastapi dev app.py --port 8080 &
+  retry -n 5 --wait 2 curl --fail localhost:8080
+
+  # [docs:curl-fastapi]
+  curl localhost:8080
+  # [docs:curl-fastapi-end]
+
+  kill $!
+
+  # [docs:create-rockcraft-yaml]
+  rockcraft init --profile fastapi-framework
+  # [docs:create-rockcraft-yaml-end]
+
+  sed -i "s/name: .*/name: fastapi-hello-world/g" rockcraft.yaml
+  sed -i "s/amd64/$(dpkg --print-architecture)/g" rockcraft.yaml
+
+  # [docs:pack]
+  ROCKCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true rockcraft pack
+  # [docs:pack-end]
+
+  # [docs:skopeo-copy]
+  rockcraft.skopeo --insecure-policy copy --dest-tls-verify=false \
+    oci-archive:fastapi-hello-world_0.1_$(dpkg --print-architecture).rock \
+    docker://localhost:32000/fastapi-hello-world:0.1
+  # [docs:skopeo-copy-end]
+
+  # [docs:create-charm-dir]
+  mkdir charm
+  cd charm
+  # [docs:create-charm-dir-end]
+
+  # [docs:charm-init]
+  charmcraft init --profile fastapi-framework --name fastapi-hello-world
+  # [docs:charm-init-end]
+
+  # update platforms in charmcraft.yaml file
+  sed -i "s/amd64/$(dpkg --print-architecture)/g" charmcraft.yaml
+
+  # [docs:charm-pack]
+  CHARMCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true charmcraft pack
+  # [docs:charm-pack-end]
+
+  # [docs:add-juju-model]
+  juju add-model fastapi-hello-world
+  # [docs:add-juju-model-end]
+
+  #[docs:add-model-constraints]
+  juju set-model-constraints -m fastapi-hello-world arch=$(dpkg --print-architecture)
+  #[docs:add-model-constraints-end]
+
+  # [docs:deploy-fastapi-app]
+  juju deploy \
+    ./fastapi-hello-world_$(dpkg --print-architecture).charm \
+    fastapi-hello-world --resource \
+    app-image=localhost:32000/fastapi-hello-world:0.1
+  # [docs:deploy-fastapi-app-end]
+
+  # [docs:deploy-nginx]
+  juju deploy nginx-ingress-integrator --channel=latest/stable --trust
+  juju integrate nginx-ingress-integrator fastapi-hello-world
+  # [docs:deploy-nginx-end]
+
+  # [docs:config-nginx]
+  juju config nginx-ingress-integrator \
+    service-hostname=fastapi-hello-world path-routes=/
+  # [docs:config-nginx-end]
+
+  # give Juju some time to deploy the apps
+  juju wait-for application fastapi-hello-world --query='status=="active"' --timeout 10m
+  juju wait-for application nginx-ingress-integrator --query='status=="active"' --timeout 10m
+
+  # [docs:curl-init-deployment]
+  curl http://fastapi-hello-world --resolve fastapi-hello-world:80:127.0.0.1
+  # [docs:curl-init-deployment-end]
+
+  cd ..
+  cat greeting_app.py > app.py
+  sed -i "s/version: .*/version: 0.2/g" rockcraft.yaml
+
+  # [docs:docker-update]
+  ROCKCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true rockcraft pack
+  rockcraft.skopeo --insecure-policy copy --dest-tls-verify=false \
+    oci-archive:fastapi-hello-world_0.2_$(dpkg --print-architecture).rock \
+    docker://localhost:32000/fastapi-hello-world:0.2
+  # [docs:docker-update-end]
+
+  cat greeting_charmcraft.yaml >> ./charm/charmcraft.yaml
+  cd charm
+
+  # [docs:refresh-deployment]
+  CHARMCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true charmcraft pack
+  juju refresh fastapi-hello-world \
+    --path=./fastapi-hello-world_$(dpkg --print-architecture).charm \
+    --resource app-image=localhost:32000/fastapi-hello-world:0.2
+  # [docs:refresh-deployment-end]
+
+  # give Juju some time to refresh the app
+  juju wait-for application fastapi-hello-world --query='status=="active"' --timeout 10m
+
+  # curl and check that the response is Hello
+  curl http://fastapi-hello-world --resolve fastapi-hello-world:80:127.0.0.1 | grep Hello
+
+  # [docs:change-config]
+  juju config fastapi-hello-world greeting='Hi!'
+  # [docs:change-config-end]
+
+  # make sure that the application updates
+  juju wait-for application fastapi-hello-world --query='status=="maintenance"' --timeout 10m
+  juju wait-for application fastapi-hello-world --query='status=="active"' --timeout 10m
+
+  # curl and check that the response is now Hi
+  curl http://fastapi-hello-world --resolve fastapi-hello-world:80:127.0.0.1 | grep Hi
+
+  cd ..
+  cat visitors_migrate.py >> migrate.py
+  cat visitors_app.py > app.py
+  sed -i "s/version: .*/version: 0.3/g" rockcraft.yaml
+
+  # [docs:docker-2nd-update]
+  ROCKCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true rockcraft pack
+  rockcraft.skopeo --insecure-policy copy --dest-tls-verify=false \
+    oci-archive:fastapi-hello-world_0.3_$(dpkg --print-architecture).rock \
+    docker://localhost:32000/fastapi-hello-world:0.3
+  # [docs:docker-2nd-update-end]
+
+  cat visitors_charmcraft.yaml >> ./charm/charmcraft.yaml
+  cd charm
+
+  # [docs:refresh-2nd-deployment]
+  CHARMCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=true charmcraft pack
+  juju refresh fastapi-hello-world \
+    --path=./fastapi-hello-world_$(dpkg --print-architecture).charm \
+    --resource app-image=localhost:32000/fastapi-hello-world:0.3
+  # [docs:refresh-2nd-deployment-end]
+
+  # [docs:deploy-postgres]
+  juju deploy postgresql-k8s --trust
+  juju integrate fastapi-hello-world postgresql-k8s
+  # [docs:deploy-postgres-end]
+
+  # give Juju some time to deploy and refresh the apps
+  juju wait-for application postgresql-k8s --query='status=="active"' --timeout 20m | juju status --relations
+  juju wait-for application fastapi-hello-world --query='status=="active"' --timeout 20m | juju status --relations
+
+  curl http://fastapi-hello-world --resolve fastapi-hello-world:80:127.0.0.1 | grep Hi
+  curl http://fastapi-hello-world/visitors --resolve fastapi-hello-world:80:127.0.0.1 | grep 1
+  curl http://fastapi-hello-world --resolve fastapi-hello-world:80:127.0.0.1 | grep Hi
+  curl http://fastapi-hello-world/visitors --resolve fastapi-hello-world:80:127.0.0.1 | grep 2
+
+  # Back out to main directory for cleanup
+  cd ..
+
+  # [docs:clean-environment]
+  # exit and delete the virtual environment
+  deactivate
+  rm -rf charm .venv __pycache__
+  # delete all the files created during the tutorial
+  rm fastapi-hello-world_0.1_$(dpkg --print-architecture).rock \
+    fastapi-hello-world_0.2_$(dpkg --print-architecture).rock \
+    fastapi-hello-world_0.3_$(dpkg --print-architecture).rock \
+    rockcraft.yaml app.py requirements.txt migrate.py
+  # Remove the juju model
+  juju destroy-model fastapi-hello-world --destroy-storage --no-prompt --force
+  # [docs:clean-environment-end]

docs/tutorial/code/fastapi/visitors_app.py

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+# FastAPI application that keeps track of visitors using a database
+
+import datetime
+import os
+from typing import Annotated
+
+from fastapi import FastAPI, Header
+import psycopg2
+
+app = FastAPI()
+DATABASE_URI = os.environ["POSTGRESQL_DB_CONNECT_STRING"]
+
+
+@app.get("/")
+async def root(user_agent: Annotated[str | None, Header()] = None):
+    with psycopg2.connect(DATABASE_URI) as conn, conn.cursor() as cur:
+        timestamp = datetime.datetime.now()
+
+        cur.execute(
+            "INSERT INTO visitors (timestamp, user_agent) VALUES (%s, %s)",
+            (timestamp, user_agent)
+        )
+        conn.commit()
+
+    return {"message": os.getenv("APP_GREETING", "Hello World")}
+
+
+@app.get("/visitors")
+async def visitors():
+    with psycopg2.connect(DATABASE_URI) as conn, conn.cursor() as cur:
+        cur.execute("SELECT COUNT(*) FROM visitors")
+        total_visitors = cur.fetchone()[0]
+
+    return {"count": total_visitors}

docs/tutorial/code/fastapi/visitors_charmcraft.yaml

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+# requires snippet for FastAPI application with a database
+
+requires:
+  postgresql:
+    interface: postgresql_client
+    optional: false

docs/tutorial/code/fastapi/visitors_migrate.py

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+# Adds database to FastAPI application
+
+import os
+
+import psycopg2
+
+DATABASE_URI = os.environ["POSTGRESQL_DB_CONNECT_STRING"]
+
+def migrate():
+    with psycopg2.connect(DATABASE_URI) as conn, conn.cursor() as cur:
+        cur.execute("""
+            CREATE TABLE IF NOT EXISTS visitors (
+                timestamp TIMESTAMP NOT NULL,
+                user_agent TEXT NOT NULL
+            );
+        """)
+        conn.commit()
+
+
+if __name__ == "__main__":
+    migrate()