Scriptorium

Terraform – Install on CentOS 8

This tutorial shows how to install Terraform on the Linux machine (CentOS 8). CentOS 8 uses DNF (Dandified yum) as a package manager.

[Kubernetes] Resources

You can configure how the Kubernetes cluster makes use of resources (such as CPU an Memory) for each pods.

[Kubernetes] Service Accounts

You can use specialized ServiceAccounts with restricted permissions to allow containers to access the Kubernetes API.

Every namespace has a default service account.
Each service account has a matching secret object, which has a token.
When a pod is created, a service account token is mounted automatically.
- The pod is accessing Kubernetes APIs using the mounted service account token.

[Kubernetes] SecurityContext

Kubernetes organizes and launches container processes. You can configure which user or group will launch the process in a docker level or in a Kubernetes level.

[Kubernetes] Commands

When you run a container in a pod, you might want to run a command at the start-up. The process consists of 2 stages – at the container (docker) level and at the Kubernetes level.

[Spark By Example] Spark SQL – UDFs

In Spark SQL, you can define your custom functions and use them in the SQL statement. The following example shows how to create a very simple UDF, register it, and use it in the SQL.

[Spark By Example] DataFrameReader

DataFrameReader is an interface to load a DataFrame from external sources.

You cannot create the DataFrameReader object, but you can access it through the “SparkSession.read” property.

[Spark By Example] Spark SQL – Grouping

Let’s play with Spark SQL more.

[Note] When the underlying DataFrame schema is changed, the view should be updated again.