feat: refreshes the token and reconnects if publishing fails

[jajeffries]

This pull request introduces robust support for automatic reconnection and JWT token refresh for the Fleet MQTT connection. The changes ensure that the agent can recover from authentication or connectivity failures by refreshing its token and re-establishing the connection without manual intervention. The implementation tracks consecutive failures in heartbeat, capabilities, and group membership publishing, triggering a reconnection sequence when thresholds are reached. Additionally, the AuthTokenManager now caches credentials and token state to enable seamless refreshes.

Automatic reconnection and JWT refresh:

• Added a reconnectChan to fleetConfigManager and MQTTConnection for signaling reconnection requests, and implemented logic to trigger reconnection after repeated failures in heartbeat, capabilities, or group membership publishing. [1] [2] [3] [4] [5]
• Implemented a goroutine in fleetConfigManager.Start that listens for reconnect requests and calls a new refreshAndReconnect method to refresh the JWT token and re-establish the MQTT connection.

Auth token management improvements:

• Enhanced AuthTokenManager to cache token credentials and expiration time, enabling token refresh via a new RefreshToken method and expiration checks via IsTokenExpired. [1] [2] [3]

Connection lifecycle enhancements:

• Added a Reconnect method to MQTTConnection to cleanly disconnect, reset failure counters, and reconnect with new credentials.
• Updated heartbeat logic to accept a failure callback and reset failure counters on successful publish, improving reliability and observability. [1] [2] [3] [4]

Test updates:

• Updated unit tests to accommodate the new reconnectChan argument and heartbeat changes, ensuring coverage of the new reconnection logic. [1] [2] [3] [4] [5]

[github-actions]

Go test coverage

STATUS	ELAPSED	PACKAGE	COVER	PASS	FAIL	SKIP
🟢 PASS	1.02s	github.com/netboxlabs/orb-agent/agent	8.2%	1	0	0
🟢 PASS	1.10s	github.com/netboxlabs/orb-agent/agent/backend	33.3%	30	0	0
🟢 PASS	4.03s	github.com/netboxlabs/orb-agent/agent/backend/devicediscovery	67.1%	2	0	0
🟢 PASS	0.20s	github.com/netboxlabs/orb-agent/agent/backend/mocks	0.0%	0	0	0
🟢 PASS	4.02s	github.com/netboxlabs/orb-agent/agent/backend/networkdiscovery	59.0%	2	0	0
🟢 PASS	4.03s	github.com/netboxlabs/orb-agent/agent/backend/opentelemetryinfinity	46.3%	2	0	0
🟢 PASS	4.03s	github.com/netboxlabs/orb-agent/agent/backend/pktvisor	67.0%	2	0	0
🟢 PASS	4.03s	github.com/netboxlabs/orb-agent/agent/backend/snmpdiscovery	58.5%	2	0	0
🟢 PASS	5.03s	github.com/netboxlabs/orb-agent/agent/backend/worker	68.1%	3	0	0
🟢 PASS	1.02s	github.com/netboxlabs/orb-agent/agent/config	100.0%	6	0	0
🟢 PASS	31.20s	github.com/netboxlabs/orb-agent/agent/configmgr	47.8%	20	0	0
🟢 PASS	5.54s	github.com/netboxlabs/orb-agent/agent/configmgr/fleet	64.3%	129	0	0
🟢 PASS	1.02s	github.com/netboxlabs/orb-agent/agent/otlpbridge	30.7%	5	0	0
🟢 PASS	1.01s	github.com/netboxlabs/orb-agent/agent/policies	100.0%	15	0	0
🟢 PASS	1.03s	github.com/netboxlabs/orb-agent/agent/policymgr	71.6%	11	0	0
🟢 PASS	23.69s	github.com/netboxlabs/orb-agent/agent/secretsmgr	48.9%	54	0	0
🟢 PASS	1.02s	github.com/netboxlabs/orb-agent/agent/telemetry	81.7%	19	0	0
🟢 PASS	1.01s	github.com/netboxlabs/orb-agent/agent/version	100.0%	1	0	0

Total coverage: 55.5%