Update notes on the Cloud native computing course

structured/assets/challenges.suse-cloud-native-fundamentals-scholarship-program/application-logging.py

@@ -0,0 +1,23 @@
+import logging
+from flask import Flask
+
+app = Flask(__name__)
+
+@app.route("/")
+def hello():
+    logging.info("/ endpoint was reached")
+    return "Hello World!"
+
+@app.route("/status")
+def health_check():
+    logging.info("/status endpoint was reached")
+    return { "result": "OK - healthy" }
+
+@app.route("/metrics")
+def metrics():
+    logging.info("/metrics endpoint was reached")
+    return { "data": { "UserCount": 140, "UserCountActive": 23} }
+
+if __name__ == "__main__":
+    logging.basicConfig(format="%(asctime)s, %(message)s", level=logging.DEBUG, filename="app.log")
+    app.run(host='0.0.0.0')

structured/assets/challenges.suse-cloud-native-fundamentals-scholarship-program/docker-packaging.sh

@@ -0,0 +1,19 @@
+OWNER="foodogsquared"
+IMG="go-helloworld"
+VERSION="1.0.0"
+REMOTE_IMG="${OWNER}/${IMG}:v${VERSION}"
+
+# Build the image with the tag already in place.
+podman build --tag "$IMG" .
+
+# Run the packaged app.
+podman run -d -p 6111:6111 "$IMG"
+
+# Verify it's running.
+podman ps
+
+# Create another image to push it into the Docker registry with the proper naming.
+podman tag "$IMG" "$REMOTE_IMG"
+
+# Push the image to the Docker registry.
+podman push "$REMOTE_IMG"

structured/assets/challenges.suse-cloud-native-fundamentals-scholarship-program/github-docker-workflow.yaml

@@ -0,0 +1,26 @@
+name: Docker build image
+on: [push]
+jobs:
+    docker:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout
+              uses: actions/checkout@v2
+            - name: Set up QEMU
+              uses: docker/setup-qemu-action@v1
+            - name: Setup Docker Buildx
+              uses: docker/setup-buildx-action@v1
+            - name: Login to DockerHub
+              uses: docker/login-action@v1
+              with:
+                  username: ${{ secrets.DOCKERHUB_USERNAME }}
+                  password: ${{ secrets.DOCKERHUB_TOKEN }}
+            - name: Build and push
+              id: docker_build
+              uses: docker/build-push-action@v2
+              with:
+                  push: true
+                  tags: ${{ secrets.DOCKERHUB_USERNAME }}/python-helloworld:latest
+                  platforms: linux/amd64,linux/arm64
+            - name: Image digest
+              run: echo ${{ steps.docker_build.outputs.digest }}

structured/assets/challenges.suse-cloud-native-fundamentals-scholarship-program/python-helloworld-app.py

@@ -0,0 +1,17 @@
+from flask import Flask
+app = Flask(__name__)
+
+@app.route("/")
+def hello():
+    return "Hello World!"
+
+@app.route("/status")
+def health_check():
+    return { "result": "OK - healthy" }
+
+@app.route("/metrics")
+def metrics():
+    return { "data": { "UserCount": 140, "UserCountActive": 23} }
+
+if __name__ == "__main__":
+    app.run(host='0.0.0.0')

structured/assets/cookbook.css.implementing-numbered-headings/naive-tiered-headings.scss

@@ -0,0 +1,55 @@
+article {
+    // Named after the LaTeX counters after `chapter` counter.
+    counter-reset: section subsection subsubsection paragraph subparagraph;
+    --counter-spacing: 0.5rem;
+
+    // <h2> is used as a section header since <h1> is the main title
+    h2 {
+        counter-reset: subsection;
+        counter-increment: section;
+
+        &::before {
+            content: counter(section) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h3 {
+        counter-reset: subsubsection;
+        counter-increment: subsection;
+
+        &::before {
+            content: counter(section) "." counter(subsection) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h4 {
+        counter-reset: paragraph;
+        counter-increment: subsubsection;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h5 {
+        counter-reset: subparagraph;
+        counter-increment: paragraph;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) "." counter(paragraph) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h6 {
+        counter-increment: subparagraph;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) "." counter(paragraph) "." counter(subparagraph);
+            margin-right: var(--counter-spacing);
+        }
+    }
+}

structured/assets/cookbook.css.implementing-numbered-headings/optimized-tiered-headings.scss

@@ -0,0 +1,28 @@
+@use 'sass:string';
+
+@function tier-heading($counters) {
+    $str: "";
+    @for $level from 1 through $counters {
+        $str: $str + 'counter(h#{$level})"."';
+    }
+    @return string.unquote($str);
+}
+
+article {
+    --counter-spacing: 0.5rem;
+    @for $level from 1 through 6 {
+        counter-reset: h#{$level};
+
+        h#{$level}{
+            @if $level != 6 {
+                counter-reset: h#{$level + 1};
+            }
+            counter-increment: h#{$level};
+
+            &::before {
+                content: tier-heading($level);
+                margin-right: var(--counter-spacing);
+            }
+        }
+    }
+}

structured/challenges.suse-cloud-native-fundamentals-scholarship-program.org

@@ -3,7 +3,7 @@
 :END:
 #+title: Solutions to SUSE Cloud native fundamentals scholarship exercises
 #+date: "2021-06-08 23:23:35 +08:00"
-#+date_modified: "2021-06-19 21:09:41 +08:00"
+#+date_modified: "2021-06-21 10:54:53 +08:00"
 #+language: en
 
 
@@ -244,7 +244,7 @@ CMD ["./helloworld"]
 
 As for the requirements of the images and running the containerized app, we'll summarize it with the following Bash script.
 
-#+begin_src bash
+#+begin_src bash  :tangle (my/concat-assets-folder "docker-packaging.sh")
 OWNER="foodogsquared"
 IMG="go-helloworld"
 VERSION="1.0.0"
@@ -532,9 +532,9 @@ To set up these credentials refer to the following resources:
 
 After creating a DockerHub access token (that serves as an alternative to passwords) and creating a GitHub encrypted secret, the workflow should now work.
 
-Here's the resulting workflow file:
+Here's the resulting GitHub Actions workflow file:
 
-#+begin_src yaml
+#+begin_src yaml  :tangle (my/concat-assets-folder "github-docker-workflow.yaml")
 name: Docker build image
 on: [push]
 jobs:

structured/cloud.github-actions.org

@@ -0,0 +1,17 @@
+#+title: GitHub Actions
+#+date: "2021-06-20 18:58:48 +08:00"
+#+date_modified: "2021-06-20 20:13:03 +08:00"
+#+language: en
+
+
+#+ATTR_ORG: :width 550
+[[file:assets/cloud.github-actions/fds-visual-github-actions-description.png]]
+
+- a CI/CD tool integrated into GitHub
+- it is free for public repos but limited time per month for private repos
+- focused into creating workflows which can be separate and applied in different contexts
+  + a workflow is activated from an event
+  + stored in ~.github/workflows~ in the remote repo
+- each workflow can run a job which are composed of steps
+- each step make uses an action which is basically a script;
+  it can interact with the repo or do something else entirely without ever touching it

structured/cookbook.css.implementing-numbered-headings.org

@@ -0,0 +1,105 @@
+:PROPERTIES:
+:ID:       6d425762-ab9c-463f-b17a-e2a116b12fa0
+:END:
+#+title: Implementing tiered headings with CSS
+#+date: "2021-06-20 10:31:00 +08:00"
+#+date_modified: "2021-06-20 18:16:24 +08:00"
+#+language: en
+
+
+You may have seen certain documents with [[https://practicaltypography.com/hierarchical-headings.html][tiered headings]].
+To implement this with pure CSS, we'll make heavy use of [[https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Lists_and_Counters/Using_CSS_counters][CSS counters]].
+
+Here is one rough implementation with SCSS.
+
+#+begin_src scss   :tangle (my/concat-assets-folder "naive-tiered-headings.scss")
+article {
+    // Named after the LaTeX counters after `chapter` counter.
+    counter-reset: section subsection subsubsection paragraph subparagraph;
+    --counter-spacing: 0.5rem;
+
+    // <h2> is used as a section header since <h1> is the main title
+    h2 {
+        counter-reset: subsection;
+        counter-increment: section;
+
+        &::before {
+            content: counter(section) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h3 {
+        counter-reset: subsubsection;
+        counter-increment: subsection;
+
+        &::before {
+            content: counter(section) "." counter(subsection) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h4 {
+        counter-reset: paragraph;
+        counter-increment: subsubsection;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h5 {
+        counter-reset: subparagraph;
+        counter-increment: paragraph;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) "." counter(paragraph) ".";
+            margin-right: var(--counter-spacing);
+        }
+    }
+
+    h6 {
+        counter-increment: subparagraph;
+
+        &::before {
+            content: counter(section) "." counter(subsection) "." counter(subsubsection) "." counter(paragraph) "." counter(subparagraph);
+            margin-right: var(--counter-spacing);
+        }
+    }
+}
+#+end_src
+
+This is enough for CSS but since we're using SCSS, we can optimize it further.
+You may notice that each level is similar with the difference being the content and their counter name.
+
+#+begin_src scss  :tangle (my/concat-assets-folder "optimized-tiered-headings.scss")
+@use 'sass:string';
+
+@function tier-heading($counters) {
+    $str: "";
+    @for $level from 1 through $counters {
+        $str: $str + 'counter(h#{$level})"."';
+    }
+    @return string.unquote($str);
+}
+
+article {
+    --counter-spacing: 0.5rem;
+    @for $level from 1 through 6 {
+        counter-reset: h#{$level};
+
+        h#{$level}{
+            @if $level != 6 {
+                counter-reset: h#{$level + 1};
+            }
+            counter-increment: h#{$level};
+
+            &::before {
+                content: tier-heading($level);
+                margin-right: var(--counter-spacing);
+            }
+        }
+    }
+}
+#+end_src

structured/linux.network-configuration.org

@@ -1,6 +1,6 @@
 #+title: Network configuration in Linux
 #+date: "2021-05-31 13:07:38 +08:00"
-#+date_modified: "2021-05-31 14:49:03 +08:00"
+#+date_modified: "2021-06-20 20:20:51 +08:00"
 #+language: en
 
 
@@ -9,6 +9,7 @@
 To access the internet, you need the following components:
 
 - The driver of the network device installed and enabled.
+  (See [[id:a7d9897e-fbaa-4ab1-a26d-4a86d2621df8][Linux drivers]] for more details.)
 - A network manager to manage your network devices ;p
 - A DNS resolver to access domain names which are aliases to IP addresses.
 
@@ -18,17 +19,16 @@ To access the internet, you need the following components:
 * Network manager configuration
 
 With a systemd-ful environment, you can run the network daemon (i.e., =systemd-networkd=).
-Once enabled, you can run =networkctl= to list all of the network devices.
+Once enabled, you can run =networkctl= to list all of the network devices. [fn:: You can also run ~ip address~ for it.]
-[fn:: You can also run ~ip address~ for it.]
 
-#+begin_src shell
+#+begin_src shell  :cache yes
 networkctl
 #+end_src
 
-#+results:
+#+results[84c83a400d07ef38e6813bc9ce677cef8a38bd66]:
 : IDX LINK   TYPE     OPERATIONAL SETUP
 :   1 lo     loopback carrier     unmanaged
-:   2 enp1s0 ether    off         unmanaged
+:   2 enp1s0 ether    routable    configured
 :   3 wlan0  wlan     routable    configured
 :
 : 3 links listed.
@@ -60,8 +60,7 @@ RouteMetric=1024
 * DNS server configuration
 
 While the network manager is enabled, you can access the internet.
-But only with raw IP addresses (e.g., 1.1.1.1 from Cloudflare, 93.174.95.27 for Library Genesis).
+But only with raw IP addresses (e.g., 1.1.1.1 from Cloudflare, 93.174.95.27 for Library Genesis). [fn:: You can find the IP addresses with DNS clients such as [[https://github.com/ogham/dog][dog]] or the [[https://nodejs.org/api/dns.html][DNS library from NodeJS]].]
-[fn:: You can find the IP addresses with DNS clients such as [[https://github.com/ogham/dog][dog]] or the [[https://nodejs.org/api/dns.html][DNS library from NodeJS]].]
 
 Accessing the domain names as you would browse the web normally is an additional layer of the web.
 To access a domain name, you need a DNS client that can resolve them.