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Main components of K8s
Master Node
| API Server | The API Server communicates with all the components within the cluster. |
| Key-Value Store (etcd) | A light-weight distributed key-value store used to accumulate all cluster data. |
| Controller | Uses the API Server to monitor the state of the cluster. It tries to move the actual state of the cluster to match the desired state from your manifest file. |
| Scheduler | Schedules newly created pods onto worker nodes. Always selects nodes with the least traffic to balance the workload. |
Worker Node
Worker nodes are the machines where the containerized workloads and storage volumes are deployed.
There are multiple instances of Worker Nodes, each performing their assigned tasks.
| Kubelet | A daemon that runs on each node and responds to the master’s requests to create, destroy, and monitor pods on that machine. |
| Container Runtime | A container runtime retrieves images from a container image registry and starts and stops containers. This is usually a 3rd party software or plugin, such as Docker. |
| Kube-proxy | A network proxy that maintains network communication to your Pods from within or from outside the cluster. |
| Add-ons (DNS, Web UI..) | Additional features you can add to your cluster to extend certain functionalities. |
| Pod | A pod is the smallest element of scheduling in Kubernetes. It represents a ‘wrapper’ for the container with the application code. If you need to scale your app within a Kubernetes cluster, you can only do so by adding or removing pods. A node can host multiple pods. |
How to create AKS
As you can see it will create 3 nodes.
Click the ‘Change Size’ to change or see the current configuration.
Find more details about the ‘Create and Manage Multiple node in Pool’.
How to connect
Connect to bash (after clicking option 1 in the right side).
How does the backup works in MongoDB?
Initial backup overview.
Below are some screen shots to understand the monitor, better.
How to create a kubernet cluster.
| SQL Terms/Concepts | MongoDB Terms/Concepts |
|---|---|
| database | database |
| table | collection |
| row | document or BSON document |
| column | field |
| index | index |
| table joins | $lookup, embedded documents |
| primary keySpecify any unique column or column combination as primary key. | primary keyIn MongoDB, the primary key is automatically set to the _id field. |
| aggregation (e.g. group by) | aggregation pipelineSee the SQL to Aggregation Mapping Chart. |
| SELECT INTO NEW_TABLE | $outSee the SQL to Aggregation Mapping Chart. |
| MERGE INTO TABLE | $merge (Available starting in MongoDB 4.2)See the SQL to Aggregation Mapping Chart. |
| UNION ALL | $unionWith (Available starting in MongoDB 4.4) |
| transactions | transactions |
MongoDB MySQL Oracle Informix DB2
Database Server mongod mysqld oracle IDS DB2 Server
Database Client mongo mysql sqlplus DB-Access DB2 Client
You can create a collection (Table) using the command line or GUI.
Here we hit the first error.
As you can see in the above error. You can’t create under the ‘admin’.
You can insert the data into collection (table) from json or csv etc.
Never to miss some important points here.
If you note it carefully from the below screenshot, you will notice that a collection(table) can be export (as you can see the arrow below 1. marked red) and even can import file or document. As already said you can import the data from csv or JSON too.
Below screenshot reminded me about the MySQL database. That also got the same options.
