Dagger.io example (#4)

docs/image/automation/index.md

@@ -107,3 +107,105 @@ Once completed you should be able to see the docker image stored on gitlab regis
 
 The container is now ready to be pulled from the registry via: `docker pull baltig.infn.it:4567/ciangottini/tutorial-ci`
 
+## Dagger.io preview
+
+- Install the [CLI](https://docs.dagger.io/quickstart/729236/cli#install-the-dagger-cli) and the [SDK](https://docs.dagger.io/quickstart/628381/sdk) via pip3, as they are needed to test the pipeline locally.
+- Then create a file in `ci/main.py` with the example code doing the following:
+    - build the flask image
+    - instantiate a webserver for tests
+    - test the response correctness
+    - publish the image
+ 
+```python
+import random
+import sys
+
+import anyio
+import httpx
+
+import json
+
+import anyio
+import dagger
+
+
+async def main():
+    config = dagger.Config(log_output=sys.stdout)
+
+    async with dagger.Connection(config) as client:
+        # set build context
+        context_dir = client.host().directory(".")
+
+        # build using Dockerfile
+        container = (
+            await context_dir.docker_build()
+        )
+
+        # execute the container as a service to be tested against
+        http_srv = (
+            container.with_env_variable(name="ENVIRONMENT", value="dagger-test")
+                .with_env_variable(name="PORT", value="8080")
+                .with_exposed_port(8080)
+                .as_service()
+        )
+
+        # expose HTTP service to host
+        tunnel = await client.host().tunnel(http_srv).start()
+
+        # get HTTP service address
+        endpoint = await tunnel.endpoint()
+
+        # access HTTP service from host
+        async with httpx.AsyncClient() as http:
+            r = await http.get(f"http://{endpoint}")
+            print(r.status_code)
+            print(r.text)
+
+            result = json.loads(r.text)
+            expected = {"env":"dagger-test"}
+            if r.status_code==200 and result==expected:
+                pass
+            elif result==expected:
+                print(f"{result}!={expected}")
+                sys.exit(1)
+            else:
+                print(f"Status code: {r.status_code}")
+                sys.exit(1)
+
+        image_ref = await container.publish(f"baltig.infn.it:4567/ciangottini/tutorial-ci-23/hello-dagger-{random.randint(0, 10000000)}")
+
+    print(f"Published image to: {image_ref}")
+
+
+
+anyio.run(main)
+```
+
+You can easily try locally the whole chain with:
+
+```bash
+dagger run python ci/main.py
+```
+
+And just as easily integrate it into a gitlab pipeline with the following content to be appended into `.gitlab-ci.yml`:
+
+```yaml
+.docker:
+  image: python:3-alpine
+  services:
+    - docker:dind
+.dagger:
+  extends: [.docker]
+  before_script:
+    - apk add docker-cli curl
+    - cd /usr/local && { curl -L https://dl.dagger.io/dagger/install.sh | sh; cd -; }
+    - docker login -u ${CI_REGISTRY_USER} -p ${CI_REGISTRY_PASSWORD} baltig.infn.it:4567
+build-deploy:
+  extends: [.dagger]
+  script:
+    - apk add python3-dev gcc libc-dev
+    - pip install --upgrade pip && pip install dagger-io httpx
+    - dagger run python ci/main.py
+```
+
+For more details and examples visit the [Dagger.io](https://docs.dagger.io/quickstart/593914/hello) documentation