Datasource Configuration

LynqHub polls your database at a configured interval, reads active rows, and reconciles the corresponding LynqNode CRs. This page covers connecting to MySQL, mapping columns to template variables, and handling common schema shapes.

Supported Datasources

Datasource	Status	Since
MySQL	Stable	v1.0
PostgreSQL	Planned	v1.2
Custom	Contribute	—

MySQL Connection

apiVersion: operator.lynq.sh/v1
kind: LynqHub
metadata:
  name: my-hub
  namespace: lynq-system
spec:
  source:
    type: mysql
    mysql:
      host: mysql.default.svc.cluster.local
      port: 3306
      username: node_reader
      passwordRef:
        name: mysql-credentials
        key: password
      database: nodes
      table: node_configs
    syncInterval: 1m

Field	Description	Default
host	MySQL hostname or IP	—
port	MySQL port	3306
username	Database user (use read-only)	—
passwordRef	Secret containing the password	—
database	Database name	—
table	Table or view name	—
syncInterval	Poll frequency (30s, 1m, 5m)	30s

Kubernetes Secret:

apiVersion: v1
kind: Secret
metadata:
  name: mysql-credentials
  namespace: lynq-system
type: Opaque
stringData:
  password: your-password-here

Column Mappings

Required

Every LynqHub needs exactly two required mappings:

valueMappings:
  uid: node_id       # unique node identifier
  activate: is_active  # activation flag

uid — Unique string identifier per row. Used in resource naming and labels.

activate — Controls whether a row is provisioned. Accepted truthy values: 1, true, TRUE, True, yes, YES, Yes. Everything else (including NULL) is treated as inactive.

Extra Mappings

Any additional columns can be mapped to template variables:

extraValueMappings:
  planId: subscription_plan   # column → template variable
  region: deployment_region
  maxUsers: max_user_count

These become available in all templates as {{ .planId }}, {{ .region }}, etc.

Schema Examples

Simple table

CREATE TABLE node_configs (
    node_id         VARCHAR(255) PRIMARY KEY,
    is_active       TINYINT(1)  DEFAULT 0,
    subscription_plan VARCHAR(50),
    deployment_region VARCHAR(50)
);

valueMappings:
  uid: node_id
  activate: is_active
extraValueMappings:
  planId: subscription_plan
  region: deployment_region

TINYINT activate column

MySQL TINYINT(1) returns the string "1" or "0" when queried — both are valid activate values.

CREATE TABLE nodes (
    id      VARCHAR(255) PRIMARY KEY,
    enabled TINYINT(1) DEFAULT 0
);

valueMappings:
  uid: id
  activate: enabled  # "1" = active, "0" = inactive

Status string (requires a VIEW)

If your activate column holds strings like "active" / "inactive", those aren't directly valid. Create a MySQL VIEW to transform them:

CREATE VIEW node_configs AS
SELECT
    id           AS node_id,
    CASE status
        WHEN 'active' THEN '1'
        ELSE '0'
    END          AS is_active,
    plan         AS subscription_plan
FROM nodes;

Then point the hub at the view name instead of the raw table. See Datasource Views for more VIEW patterns.

Best Practices

Use a read-only database user. Lynq only needs SELECT on the target table/view.

CREATE USER 'node_reader'@'%' IDENTIFIED BY 'secure_password';
GRANT SELECT ON nodes.node_configs TO 'node_reader'@'%';
FLUSH PRIVILEGES;

Use a VIEW to isolate sensitive columns. Grant SELECT only on the view, not the underlying table.

Index the activate column for faster filtering at scale:

CREATE INDEX idx_active ON nodes(is_active);

Set syncInterval based on scale:

syncInterval: 30s  # development
syncInterval: 1m   # production (recommended)
syncInterval: 5m   # large deployments (1000+ nodes)

Troubleshooting

Nodes not created — check activate values:

SELECT node_id, is_active FROM node_configs
WHERE is_active NOT IN ('0', '1', 'true', 'false', 'yes', 'no', 'TRUE', 'FALSE');
-- Any rows here have invalid activate values

Check operator logs for sync errors:

kubectl logs -n lynq-system -l control-plane=controller-manager | grep -i "hub\|sync\|query"

Connection errors — test from inside the cluster:

kubectl run mysql-test --rm -it --image=mysql:8 -- \
  mysql -h mysql.default.svc.cluster.local -u node_reader -p

Verify the Secret:

kubectl get secret mysql-credentials -n lynq-system -o jsonpath='{.data.password}' | base64 -d

Caveats

hostOrUrl mapping is deprecated (since v1.1.11, removed in v1.3.0). If your hub currently uses it:

# Deprecated
valueMappings:
  hostOrUrl: node_url

# Migrate to:
extraValueMappings:
  nodeUrl: node_url
# Then use {{ .nodeUrl | toHost }} in templates instead of {{ .host }}

See Also

• Datasource Views — VIEW patterns and a complete pre-deployment verification checklist
• Templates — using datasource variables in templates
• Security — credential management
• Contributing a Datasource — add PostgreSQL or another source