musl is an implementation of C standard library. It is more lightweight, faster and simpler than glibc used by other Linux distros, such as Ubuntu.

Some of it stems from how musl (and therefore also Alpine) handles DNS (it's always DNS), more specifically, musl (by design) doesn't support DNS-over-TCP.

By using Alpine, you're getting "free" chaos engineering for you cluster.

Data Definition Language (DDL) is used to create and modify the structure of objects in a database using predefined commands and a specific syntax.

DDL includes Structured Query Language (SQL) statements to create and drop databases, aliases, locations, indexes, tables and sequences.

Since DDL includes SQL statements to define changes in the database schema, it is considered a subset of SQL.

One of the common challenges when capturing data changes from your source tables is how to handle DDL changes to the source tables.

Change Data Capture

SQL statements are divided into two categories: Data Definition Language (DDL) and Data Manipulation Language (DML).

DDL operations on a table may affect dependent objects such as constraints and Indexes.

If using a ClusterIssuer, remember to update the Ingress annotation cert-manager.io/issuer to cert-manager.io/cluster-issuer

Certificates resources allow you to specify the details of the certificate you want to request.

An Issuer defines how cert-manager will request TLS certificates.

On most Kubernetes clusters, the ingress controller will work without requiring any extra configuration.

NodePort, as the name says, means that a port on a node is configured to route incoming requests to a certain service.

LoadBalancer is a service, which is typically implemented by the cloud provider as an external service (with additional cost).

In order for the Ingress resource to work, the cluster must have an ingress controller running.

If you do not specify an IngressClass for an Ingress, and your cluster has exactly one IngressClass marked as default, then Kubernetes applies the cluster's default IngressClass to the Ingress.

With stacked control plane nodes, where etcd nodes are colocated with control plane nodes

A stacked HA cluster is a topology where the distributed data storage cluster provided by etcd is stacked on top of the cluster formed by the nodes managed by kubeadm that run control plane components.

Each control plane node runs an instance of the kube-apiserver, kube-scheduler, and kube-controller-manager

(Recommended) If you have plans to upgrade this single control-plane kubeadm cluster to high availability you should specify the --control-plane-endpoint to set the shared endpoint for all control-plane nodes

set the --pod-network-cidr to a provider-specific value.

kubeadm tries to detect the container runtime by using a list of well known endpoints.

Calico is a networking and network policy provider. Calico supports a flexible set of networking options so you can choose the most efficient option for your situation, including non-overlay and overlay networks, with or without BGP. Calico uses the same engine to enforce network policy for hosts, pods, and (if using Istio & Envoy) applications at the service mesh layer.

Cilium is a networking, observability, and security solution with an eBPF-based data plane. Cilium provides a simple flat Layer 3 network with the ability to span multiple clusters in either a native routing or overlay/encapsulation mode, and can enforce network policies on L3-L7 using an identity-based security model that is decoupled from network addressing. Cilium can act as a replacement for kube-proxy; it also offers additional, opt-in observability and security features.

CoreDNS is a flexible, extensible DNS server which can be installed as the in-cluster DNS for pods.

the systemd driver is recommended for kubeadm based setups instead of the cgroupfs driver, because kubeadm manages the kubelet as a systemd service.

Kubernetes releases before v1.24 included a direct integration with Docker Engine, using a component named dockershim. That special direct integration is no longer part of Kubernetes

You need to install a container runtime into each node in the cluster so that Pods can run there.

to promote an existing cluster for production use

Separating the control plane from the worker nodes.

Having enough worker nodes available

Terraform relies on plugins called providers to interact with cloud providers, SaaS providers, and other APIs.

Terraform configurations must declare which providers they require so that Terraform can install and use them.

Each provider adds a set of resource types and/or data sources that Terraform can manage.

Each provider may offer data sources alongside its set of resource types.

When distinguishing from data resources, the primary kind of resource (as declared by a resource block) is known as a managed resource.

Each data resource is associated with a single data source, which determines the kind of object (or objects) it reads and what query constraint arguments are available.

triggers - A map of values which should cause this set of provisioners to re-run. Values are meant to be interpolated references to variables or attributes of other resources.

A given resource or module block cannot use both count and for_each

each.key — The map key (or set member) corresponding to this instance.

the native syntax of the Terraform language, which is a rich language designed to be relatively easy for humans to read and write.

Terraform's configuration language is based on a more general language called HCL, and HCL's documentation usually uses the word "attribute" instead of "argument."

A particular block type may have any number of required labels, or it may require none