Update my notebook

Most of them are random updates. Also moving up to Lesson 5 from the
SUSE Cloud native fundamentals program.

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

@@ -1,6 +1,9 @@
+:PROPERTIES:
+:ID:       0617c544-0d04-4a55-9d70-b8b4998fad92
+:END:
 #+title: Solutions to SUSE Cloud native fundamentals scholarship exercises
 #+date: "2021-06-08 23:23:35 +08:00"
-#+date_modified: "2021-06-12 12:24:19 +08:00"
+#+date_modified: "2021-06-16 18:18:39 +08:00"
 #+language: en
 
 
@@ -333,3 +336,173 @@ While the solution gave it as user and passwords, the kubeconfig I have seem to
 
 Also, you can get the configuration of the cluster with ~kubectl config view~.
 Pretty handy.
+
+
+
+
+* Kubernetes resources
+
+Now you have learned many Kubernetes recourses, in this exercise, you will deploy the following resources using the kubectl command.
+
+- a namespace
+  + name: =demo=
+  + label: =tier: test=
+- a deployment:
+  + image: =nginx:alpine=
+  + name: =nginx-apline=
+  + namespace: =demo=
+  + replicas: =3=
+  + labels: =app: nginx, tag: alpine=
+- a service:
+  + expose the above deployment on port 8111
+  + namespace: =demo=
+- a configmap:
+  + name: =nginx-version=
+  + containing key-value pair: =version=alpine=
+  + namespace: =demo=
+
+
+** Solution
+
+This is practical test but it can summarized with a shell script.
+
+#+begin_src bash  :eval no
+# Create the namespace with the specified label.
+kubectl create namespaces demo
+kubectl label namespaces demo tier=test
+
+# Create the specified deployment.
+kubectl create deployment nginx-alpine --image=nginx:alpine --replicas=3 --namespace=demo
+kubectl label deployment nginx-alpine app=nginx tag=alpine --namespace=demo
+
+# Expose the deployment as a service.
+kubectl expose deployment nginx-alpine --namespace=demo --port=8111
+
+# Create the config map.
+kubectl create configmaps nginx-version --namespace=demo --from-literal=version=alpine
+#+end_src
+
+
+
+
+* Declarative Kubernetes manifests
+
+Kubernetes is widely known for its imperative and declarative management techniques.
+In the previous exercise, you have deployed the following resources using the imperative approach.
+Now deploy them using the declarative approach.
+
+- a namespace
+  + name: demo
+  + label: tier: test
+- a deployment:
+  + image: nginx:alpine
+  + name:nginx-apline
+  + namespace: demo
+  + replicas: 3
+  + labels: app: nginx, tag: alpine
+- a service:
+  + expose the above deployment on port 8111
+  + namespace: demo
+- a configmap:
+  + name: nginx-version
+  + containing key-value pair: version=alpine
+  + namespace: demo
+
+
+** Solution
+
+Since they ask for 4 resources, we need 4 manifests.
+We'll create four YAML manifests for this exercise.
+
+The following manifests are created with the option to print the resources in YAML format with some modifications.
+
+Here's one for the namespace.
+The command used to make the template is ~kubectl create namespace demo --dry-run=client --output=yaml~.
+
+#+begin_src yaml
+apiVersion: v1
+kind: Namespace
+metadata:
+  creationTimestamp: null
+  name: demo
+  labels:
+    tier: test
+spec: {}
+status: {}
+#+end_src
+
+The manifest for the deployment.
+The command used to create the starting template is ~kubectl create deployment nginx-alpine --namespace=demo --replicas=3 --image=nginx:alpine --dry-run=client --output=yaml~.
+
+#+begin_src yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  creationTimestamp: null
+  labels:
+    app: nginx
+    tag: alpine
+  name: nginx-alpine
+  namespace: demo
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: nginx-alpine
+  strategy: {}
+  template:
+    metadata:
+      creationTimestamp: null
+      labels:
+        app: nginx-alpine
+    spec:
+      containers:
+      - image: nginx:alpine
+        name: nginx
+        resources: {}
+status: {}
+#+end_src
+
+The service manifest should be created after the deployment manifest is applied (i.e., ~kubectl apply -f deployment.yaml~).
+It is created with ~kubectl expose deploy nginx-alpine --port=8111 --dry-run=client --output=yaml --namespace=demo~.
+
+#+begin_src yaml
+apiVersion: v1
+kind: Service
+metadata:
+  creationTimestamp: null
+  labels:
+    app: nginx
+    tag: alpine
+  name: nginx-alpine
+  namespace: demo
+spec:
+  ports:
+  - port: 8111
+    protocol: TCP
+    targetPort: 8111
+  selector:
+    app: nginx-alpine
+status:
+  loadBalancer: {}
+#+end_src
+
+The resulting YAML output is from running the command (i.e., ~kubectl create configmap nginx-version --from-literal=version=alpine --dry-run=client --output=yaml --namespace=demo~).
+No cleaning up is required.
+
+#+begin_src yaml
+apiVersion: v1
+data:
+  version: alpine
+kind: ConfigMap
+metadata:
+  creationTimestamp: null
+  name: nginx-version
+  namespace: demo
+#+end_src
+
+
+** Findings after solution
+
+Aside from the mostly correct answers, I also found out ~kubectl get all -n demo~ to get all of the resources in the specified namespace.
+Pretty handy for inspecting application-specific resources.

structured/cli.fzf.org

@@ -3,7 +3,7 @@
 :END:
 #+title: fzf
 #+date: "2021-05-31 23:08:57 +08:00"
-#+date_modified: "2021-06-04 07:52:35 +08:00"
+#+date_modified: "2021-06-14 22:33:37 +08:00"
 #+language: en
 
 
@@ -64,7 +64,7 @@ function fzf-cd() {
 }
 #+end_src
 
-Even better when you bind it with a keyboard shortcut (e.g., ~bind '"\C-f":'fzf-cd\n"'~).
+Even better when you bind it with a keyboard shortcut (e.g., ~bind '"\C-f":'fzf-cd\n"'~ on your Bash config).
 
 
 ** Package selection in Arch Linux

structured/cli.kubectl.org

@@ -3,7 +3,7 @@
 :END:
 #+title: kubectl
 #+date: "2021-06-13 00:29:49 +08:00"
-#+date_modified: "2021-06-14 22:48:57 +08:00"
+#+date_modified: "2021-06-14 23:27:29 +08:00"
 #+language: en
 #+property: header-arg  :eval no
 
@@ -18,6 +18,10 @@ The main binary when managing [[id:9e4f04d4-00a3-4898-ac98-924957fa868b][Kuberne
 - =api-resource= lists all of the resources it currently supports.
 - =cluster-info= prints information of the cluster and the add-ons installed.
 - =create [RESOURCE] [NAME]= creates the specified resource with the given name.
+  + =--dry-run= just initiates the process and does nothing.
+    Useful with =-o yaml= to create a minimal manifest.
+  + =-o [yaml|json|wide]= prints the created resource as the specified output.
+    Specially useful to create manifests and manage clusters declaratively.
 - =describe [RESOURCE] [NAME]= prints a detailed description of the given resource.
 - =logs [RESOURCE] [NAME]= shows the log printed from the given resource.
 - =explain [RESOURCE]= prints an explaination of the given resource — e.g., ~kubectl explain pods~, ~kubectl explain rs~.
@@ -26,17 +30,7 @@ The main binary when managing [[id:9e4f04d4-00a3-4898-ac98-924957fa868b][Kuberne
     You can also print [[https://kubernetes.io/docs/reference/kubectl/overview/#custom-columns][the columns]] you only need.
 - =apply= applies a manifest, that is, a configuration file.
 
-
-** Resource names
-
-Most of the subcommands require a resource type and a name.
-You can also refer to a specific resource with =${RESOURCE}/${NAME}= — e.g., =namespace/demo=, =deploy/hello=.
-
-In the command line, you can refer to it like the following.
-
-- ~kubectl create ns/demo~
-- ~kubectl describe deploy/hello~
-- ~kubectl create pod/python-app --namespace=demo~
+When referring to a specific resource with =${RESOURCE}/${NAME}= — e.g., =namespace/demo=, =deploy/hello=.
 
 
 

structured/lang.oil.org

@@ -1,6 +1,6 @@
 #+title: Oil shell
 #+date: "2021-05-09 16:40:50 +08:00"
-#+date_modified: "2021-06-05 16:36:01 +08:00"
+#+date_modified: "2021-06-14 22:26:24 +08:00"
 #+language: en
 #+property: header-args:oil  :eval no
 
@@ -70,7 +70,7 @@ for i in @keywords { echo "keyword: $i" }
 
 ** Strings
 
-While strings are similar to Bash strings [fn:: Really more like Python strings.], there are subtle differences.
+While strings are similar to Bash strings[fn:: Really more like Python strings.], there are subtle differences.
 Most notably, Bash splits the string when trying to do something.
 
 #+begin_src bash

structured/literature.cs50x.org

@@ -3,7 +3,7 @@
 :END:
 #+title: CS50x
 #+date: "2021-06-06 17:58:08 +08:00"
-#+date_modified: "2021-06-06 20:07:35 +08:00"
+#+date_modified: "2021-06-15 12:30:13 +08:00"
 #+language: en
 #+source: https://courses.edx.org/courses/course-v1:HarvardX+CS50+X/course/
 
@@ -35,3 +35,11 @@ I'll finish this thing for real this time.
   + boolean expressions are yes/no questions to a conditional, entering that branch if said condition is met
   + abstractions are one way of solving a problem by framing the problem one level higher, focusing on the problems without worrying on the details;
     we could also think abstractions as wishful thinking
+
+
+
+
+* Week 1
+
+- writing good code should be foremost correct
+- but style is also important just like with writing requiring correct use of punctuations and grammar

structured/literature.fundamentals-of-music-theory.org

@@ -3,7 +3,7 @@
 :END:
 #+title: Fundamentals of music theory
 #+date: "2021-04-29 18:27:29 +08:00"
-#+date_modified: "2021-05-18 15:26:56 +08:00"
+#+date_modified: "2021-06-16 18:40:52 +08:00"
 #+language: en
 #+source: https://www.coursera.org/learn/edinburgh-music-theory/
 
@@ -46,7 +46,7 @@ Keep in mind this course mainly deals with western musical concepts and notation
   When the distance of each note is 2 semitone, it is considered as a tone.
 
 #+ATTR_ORG: :width 550
-[[file:assets/2021-04-29-18-27-29/fds-visual-octaves-and-tones.png]]
+[[file:assets/literature.fundamentals-of-music-theory/fds-visual-octaves-and-tones.png]]
 
 - an interval is two pitches with a certain distance
   + starting from a note, the number of tones distanced between them is the name of an interval
@@ -79,7 +79,7 @@ Keep in mind this course mainly deals with western musical concepts and notation
 #+end_src
 
 #+results:
-[[file:assets/2021-04-29-18-27-29/modes.png]]
+[[file:assets/literature.fundamentals-of-music-theory/modes.png]]
 
 - chords are three or more notes played together
   + when played with three, it is considered a triad
@@ -97,7 +97,7 @@ Keep in mind this course mainly deals with western musical concepts and notation
 #+end_src
 
 #+results:
-[[file:assets/2021-04-29-18-27-29/chords.png]]
+[[file:assets/literature.fundamentals-of-music-theory/chords.png]]
 
 
 
@@ -114,7 +114,7 @@ Keep in mind this course mainly deals with western musical concepts and notation
 #+end_src
 
 #+results:
-[[file:assets/2021-04-29-18-27-29/accidentals.png]]
+[[file:assets/literature.fundamentals-of-music-theory/accidentals.png]]
 
 #+begin_src lilypond  :file accidental-with-chords.png
 <<lilypond-paper-config>>
@@ -123,4 +123,4 @@ Keep in mind this course mainly deals with western musical concepts and notation
 #+end_src
 
 #+results:
-[[file:assets/2021-04-29-18-27-29/accidental-with-chords.png]]
+[[file:assets/literature.fundamentals-of-music-theory/accidental-with-chords.png]]

structured/literature.reproducible-research-methodological-principles-for-transparent-science.org

@@ -3,9 +3,9 @@
 :END:
 #+title: Reproducible research: methodological principles for transparent science
 #+date: "2020-04-12 10:24:25 +08:00"
-#+date_modified: "2021-06-05 20:29:35 +08:00"
+#+date_modified: "2021-06-13 14:18:21 +08:00"
 #+language: en
-#+source :: https://www.fun-mooc.fr/courses/course-v1:inria+41016+self-paced/about
+#+source: https://www.fun-mooc.fr/courses/course-v1:inria+41016+self-paced/about
 #+tags: @fleeting courses research.reproducibility
 
 

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

@@ -3,11 +3,12 @@
 :END:
 #+title: SUSE Cloud native fundamentals scholarship program
 #+date: "2021-06-07 18:21:19 +08:00"
-#+date_modified: "2021-06-13 15:59:44 +08:00"
+#+date_modified: "2021-06-16 19:46:33 +08:00"
 #+language: en
 
 
 A course from Udacity with SUSE from their scholarship program.
+If you're interested in the exercises for other solutions, see [[id:0617c544-0d04-4a55-9d70-b8b4998fad92][Solutions to SUSE Cloud native fundamentals scholarship exercises]].
 
 Some things to keep in mind:
 
@@ -91,3 +92,35 @@ Best practices for application deployment:
   + services
   + ConfigMaps handles pod configurations
   + namespaces provide separation of logic between different applications, that is, application context
+
+
+
+
+
+* Lesson 4
+
+- small organizations do not often have the resources to manage their own clusters thus often use third-party providers;
+  while some organizations do have the resources, the scope to manage clusters often overshadow the team managing it
+
+- in cases like those, it make sense to use Platform-as-a-Service platforms (PaaS)
+
+- there are different components in a technology stack that an organization can manage:
+  starting from servers, storage, virtualization, operating system, runtime, data, and application
+
+- several providers are offering the above components and usually go into several umbrellas:
+  + the organization can choose no provider and instead manage their own with their own hardware, infrastructure, and all;
+    having an on-premises instance lets the organization full control of the whole stack but it can take a while to setup before the team can manage their deployments
+
+  + some organizations will choose a provider that offers a infrastructure-as-a-service (IaaS) — e.g., Google Cloud Platform, Amazon Web Services — just not providing a way to manage the hardware (e.g., servers, storage)
+
+  + others will choose platform-as-a-service (PaaS), reducing further what the organization can manage, only the application and the data
+
+  + some providers offer functions-as-a-service (FaaS) — e.g., Amazon Lambda, Netlify Lambda — that only invokes the application on-demand
+
+- the point is the more the organization has full control of, the more complexity the organization has to worry about;
+  while they have full control over the stack, they have also to cover the full expense for managing it;
+  having more control also means less chances of being vendor lock-in, thus, more flexibility with more options to add and remove features into the market
+
+- the less components they have control over, the less complexity;
+  with less things to worry about, it takes less time to create prototypes and less overall expenses;
+  but since they delegate the tasks to a third-party provider, they are vulnerable to vendor lock-in, thus, can only move from the limitations of the platform;

structured/tools.nix.org

@@ -3,7 +3,7 @@
 :END:
 #+title: The basics of Nix package manager
 #+date: "2021-06-05 12:34:49 +08:00"
-#+date_modified: "2021-06-09 17:39:23 +08:00"
+#+date_modified: "2021-06-15 10:37:05 +08:00"
 #+language: en
 
 
@@ -70,7 +70,7 @@ let overlay = self: super:
 #+end_src
 
 # TODO: Bring more examples
-For another example, you can see some examples from [[https://github.com/neovim/neovim/blob/f695457f815544d0dc16469569c70556e3165bb6/contrib/flake.nix][Neovim]] (which also uses Nix flakes).
+For another example, you can see some examples from [[https://github.com/neovim/neovim/blob/f695457f815544d0dc16469569c70556e3165bb6/contrib/flake.nix][Neovim]] and [[https://gitlab.com/veloren/veloren/-/tree/685f4971ac0deb31b301e9d2bc0201d2531fd895/nix][Veloren]] (which also uses Nix flakes).
 
 You can set overlays automatically either by setting =nixpkgs.overlays= from your system configuration or =~/.config/nixpkgs/overlays/= folder for user-specific settings.
 You could also set overlays for standalone Nix code similarly through the =overlays= key — e.g., ~import <nixpkgs> ? { overlays = (self: super: { } ); };~.