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atlas-db-controller

Current support only for Postgres database; other databases are under development.

Atlas-db-controller is used to create custom resource and manage them.

It manages 3 types of resources:

  • Database Servers
  • Databases
  • Database Schemas

The DatabaseServer resource will instantiate a database server and create a Secret that contains the DSN to connect to the database instance as the super user.

This secret is then used by the Database resource, which will create specific application database on that server, along with users and associated Secrets as defined in the spec. At least one user with administrative access to the database is required.

DatabaseSchema resource will use the administrative Secret created by the Database resource to install and maintain a specific version of the database schema.

Prerequisite

  • Kubernetes cluster version should be > 1.9
  • Migration/Initialization scripts should comply with these guidelines.
  • To access gitHub source need user's personal access tokens
  • GitHub and AWS S3 are the only supported source for migration scripts.
  • Current end to end support for Postgres database only.

Custom Resources and Controller deployment

Users need to create custom resources and controller instance to manage custom resources in kubernetes cluster.

Custom Resource

To read about Custom resource follow link.

To create the custom resources execute:

kubectl create -f ./deploy/crd.yaml

This will define DatabaseServers, Database and DatabaseSchema custom resource in kubernetes cluster.

Controller

To create the controller:

kubectl create -f ./deploy/namespace.yaml
kubectl create -f ./deploy/atlas-db.yaml

If user wishes to deploy controller in a different namespace; edit namespace.yaml and atlas-db.yaml files respectively.

Alternatively several developer options can be configured in atlas-db.yaml to customize the controller deployment as follow:

  • resync: Resync duration
  • logtostderr: Logs are written to standard error instead of files.
  • log: log level
  • v: Enable debug mode
  • LabelSelector: A selector to restrict the list of returned objects by their labels. If user do not specify this option, atlas-db-controller will default to everything.
...
imagePullPolicy: Always
args:
  - "-resync=3m"
  - "-logtostderr"
  - "-v=4"
  - "-log=error"
  - "-l=monitor=atlas-deployment-1"

For LabelSelector option to work as intended, resources should have proper labelling.

<!--
dbserverA.yaml
-->

...
kind: DatabaseServer
metadata:
  name: postgres
  labels:
    monitor: atlas-deployment-1
  spec:
...

atlas-db resources and deployments

Following section describes the custom resources created and managed by atlas-db-controller.

Database Servers

Database Server resource is used manage the lifecycle of a database server instance. RDS DB servers are planned to provision manually.

Pod-Based Servers

User can create servers that are backed by pods on the local cluster. Note that these are not production-class deployments, and are meant for development purposes only.

These will result in the creation of 3 resources:

  • A Pod with the same name as the DatabaseServer resource.
  • A cluster IP Service with the same name as the DatabaseServer resource.
  • A Secret with the DSN to connect as super-user to the database.
PostgreSQL

To create a Postgres database server instance, user specify the Postgres member of the DatabaseServer resource.

apiVersion: atlasdb.infoblox.com/v1alpha1
kind: DatabaseServer
metadata:
  name: mydbserver
spec:
  servicePort: 5432
  superUser: "postgres"
  superUserPassword: "postgres"
  postgres:
    image: postgres
MySQL

To create a MySQL database server instance, user specify the MySQL member of the DatabaseServer resource.

apiVersion: atlasdb.infoblox.com/v1alpha1
kind: DatabaseServer
metadata:
  name: mydbserver
spec:
  servicePort: 3306
  rootPassword: "root"
  mySQL:
    image: mysql

Cloud Servers

NOTE: RDS database server needs to be provisioned manually and user should get login credentials.

When using External Database server or RDS database instance user need to create a database server resource in Kubernetes cluster which will create an external service referring to External Database server or RDS database instance.

These will result in the creation of 2 resources:

  • A Externalname Service with the same name as the DatabaseServer resource.
  • A Secret with the DSN to connect as super-user to the database.
apiVersion: atlasdb.infoblox.com/v1alpha1
kind: DatabaseServer
metadata:
  name: mydbserver
spec:
  servicePort: 5432
  superUser: "postgres"
  superUserPassword: "postgres"
  dbHost: "aws.rds.db.instance.infoblox.com"
  rds:
    engine: postgres

Databases

Database resources are used to manage the lifecycle of specific databases on a database server instance. This resource will create specified user in the database instance as well. An user with admin role is a must.

This resource will also create a Secret with the DSN to connect as admin-user to the database. User can skip this by not providing "users" information. That implies DatabaseSchema will use user provided dsn to connect to database resource.

apiVersion: atlasdb.infoblox.com/v1alpha1
kind: Database
metadata:
  name: mydb
spec:
  users:
  - name: mydb
    password: foo
    role: read
  - name: mydbadmin
    passwordFrom:
      secretKeyRef:
        name: mydbsecrets
        key: adminpw
  server: mydbserver

Database Schemas

Database Schema resource is used to manage the lifecycle of the schemas within a database. This allows automated migration of database objects such as tables and triggers; and manages the execution versioning of those migrations.

apiVersion: atlasdb.infoblox.com/v1alpha1
kind: DatabaseSchema
metadata:
  name: myschema
spec:
  database: mydb
  source: github://iburak-infoblox:<place password or oauth token here>@infobloxopen/atlas-contacts-app/db/migrations
  version: 001

User can use sourceFrom as an alternate to source to secure the credentials.

NOTE: Need to use different names for resources database server, database and database schema. If same name given for all the resources, will get this error "secret already exists".

Additional details

construct of GitHub url as a Source

github://user:personal-access-token@owner/repo/path#ref

URL Query Description
user The username of the user connecting to github
personal-access-token An access token from Github link
owner The repo owner
repo The name of the git repository
path Path in the git repository to migrations
ref (optional) can be a SHA, branch, or tag

construct of S3 Url as a Source

s3://<bucket-name>/<prefix>

URL Query Description
bucket-name name of the bucket in which migration file lives.
prefix (optional) Limits the response to keys that begin with the specified prefix.

Steps to create kubernetes secrets to secure (passwords, dsn, sourceURL)

Assume 'infoblox@123' is the password for admin user.

First base64 encode it.

$ echo -n "infoblox@123" | tr -d '\n' | base64
aW5mb2Jsb3hAMTIz

User have to update this base64 encoded value below

...
apiVersion: v1
kind: Secret
metadata:
  name: mydbsecret
  namespace: default
type: Opaque
data:
  adminUserPass: aW5mb2Jsb3hAMTIz
  dsn: <UPDATE YOUR ENCODED VALUE>

Additional way to create secret is to update the value in a file say /tmp/dsn

$cat /tmp/dsn
postgres://postgres:[email protected]:5432/postgres?sslmode=disable"

Then execute the below command to create secret named mydbsecret with key dsn in default namespace.

kubectl create secret -n default generic mydbsecrets --from-file=/tmp/dsn

FAQ

Q: How can I connect to database created by atlas-db from an application?

A: In application deployment file, provide the dsn secret name with the same name as database resource. For eg.

spec:
      containers:
      - name: server
        env:
        - name: dsn
          valueFrom:
            secretKeyRef:
              name: mydb
              key: dsn
        args:
        - "-db=$(dsn)"

Here it is given as "mydb", replace it with your database resource name.