Easy everything in DevOps & Cloud, page 5
Read replicas in managed relational databases
A read replica is an async copy of the primary that serves read-only queries, offloading the primary and scaling read-heavy workloads; expect replication lag.
Choosing relational vs NoSQL managed databases
Choose relational for complex relationships, joins, flexible queries, and strong transactions; choose NoSQL for known access patterns needing massive horizontal scale.
Security Groups vs NACLs
A security group is stateful and attached to instances or NICs; a NACL is stateless and applied at the subnet.
IAM Role vs IAM User
A user is a fixed identity with long-lived credentials for a person; a role is assumable with temporary credentials for workloads or cross-account access.
How cloud DNS resolves a URL to an IP
Recursive resolver queries root, then TLD, then your authoritative cloud DNS zone; the matching record returns an IP, cached per TTL.
Layer 4 vs Layer 7 load balancers
Layer 4 load balancers route transport connections using addresses, ports and protocol information. Layer 7 balancers can route HTTP requests by host, path or headers. Choose for the protocols and routing rules you need; Layer 7 is not always an upgrade.
Public and private subnet VPC design
Web server in a public subnet routed to an internet gateway, database in a private subnet with no inbound from the internet, NAT for outbound.
Serving user images securely from object storage
Store images in a private bucket, serve via a CDN with origin access control, use signed URLs for private content.
Object vs block vs file storage
Object stores flat keyed blobs over HTTP, block gives raw volumes for one VM, file offers a shared hierarchical mount.
What a machine image is and why it matters
An image is a frozen template of OS, software, and config; it makes launches identical and fast.
Launching a virtual machine in the cloud
Pick image, instance type, network placement and security, attached storage, and access keys.
CapEx vs OpEx in cloud migration
CapEx is large upfront asset spend, OpEx is ongoing pay-as-you-go cost; cloud shifts spending from CapEx to OpEx, trading ownership for flexibility.
The sidecar proxy pattern in a mesh
A proxy container shares the pod, all in/out traffic is redirected through it, so policy and telemetry apply without code changes.
What a service mesh solves
It adds traffic management, security via mTLS, and observability at the network layer through sidecars, beyond what plain Kubernetes offers.
Creating an instance of a custom resource
Write a manifest with apiVersion (group/version), kind, metadata.name, and a spec matching the CRD schema, then kubectl apply -f it.
Core components of a Kubernetes Operator
A CRD defines the type, a controller watches instances via the API server and runs a reconcile loop, encoding operational knowledge to drive real state.
What is a Custom Resource Definition?
A CRD registers a new resource kind so the API server stores and serves it like built-ins; it lets you model domain concepts declaratively.
Override Helm values at install time
Pass custom files with -f or --values, single keys with --set, and know precedence: defaults, then files, then --set.
What is the basic principle of GitOps?
Git holds desired state; a controller continuously reconciles the cluster to match it; benefits are auditability, rollback, and drift correction.
What is a Helm chart?
A chart is a templated, versioned bundle of manifests with a values file; it solves config duplication and reuse across environments.
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