K8s: Instead of probe to restart Distributor, adding event bus heartbeat to prevent steal connection

[VietND96]

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Description

Disable the custom exec probe to restart the Distributor as a workaround if there is no Node able to register with the Distributor.
Now, [grid] Add event bus heartbeat to prevent steal connection - SeleniumHQ/selenium#16444
So, issue Distributor Requires Restart to Register New Nodes After Hours of Inactivity could be resolved.

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

Enhancement

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Description

• Add event bus heartbeat period configuration support across all Selenium Grid components

• Enable SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable in startup scripts

• Change default component liveness probe from exec to httpGet in Helm charts

• Prevent connection stealing by implementing heartbeat mechanism in event bus

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Diagram Walkthrough

flowchart LR
  ENV["SE_EVENT_BUS_HEARTBEAT_PERIOD<br/>Environment Variable"]
  SCRIPTS["Startup Scripts<br/>EventBus, Hub, Standalone,<br/>StandaloneDocker"]
  OPTS["--eventbus-heartbeat-period<br/>Command Option"]
  HELM["Helm Chart<br/>defaultComponentLivenessProbe"]
  
  ENV -- "passed to" --> SCRIPTS
  SCRIPTS -- "appends" --> OPTS
  HELM -- "updated default" --> HELM

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File Walkthrough

	Relevant files
Enhancement	start-selenium-grid-eventbus.sh Add event bus heartbeat period configuration                          EventBus/start-selenium-grid-eventbus.sh Add conditional check for SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable Append --eventbus-heartbeat-period option to Selenium Grid startup command +4/-0      start-selenium-grid-hub.sh Add event bus heartbeat period configuration                          Hub/start-selenium-grid-hub.sh Add conditional check for SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable Append --eventbus-heartbeat-period option to Selenium Grid startup command +4/-0      start-selenium-standalone.sh Add event bus heartbeat period configuration                          Standalone/start-selenium-standalone.sh Add conditional check for SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable Append --eventbus-heartbeat-period option to Selenium Grid startup command +4/-0      start-selenium-grid-docker.sh Add event bus heartbeat period configuration                          StandaloneDocker/start-selenium-grid-docker.sh Add conditional check for SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable Append --eventbus-heartbeat-period option to Selenium Grid startup command +4/-0
Documentation	CONFIGURATION.md Update default component liveness probe documentation        charts/selenium-grid/CONFIGURATION.md Update default value for global.seleniumGrid.defaultComponentLivenessProbe from exec to httpGet Align documentation with Helm chart configuration changes +1/-1
Configuration changes	values.yaml Change default component liveness probe method                      charts/selenium-grid/values.yaml Change defaultComponentLivenessProbe default value from exec to httpGet Update Helm chart configuration for component health checks +1/-1

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[qodo-merge-pro]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	Unvalidated input Description: Passing the heartbeat period from an environment variable directly to a command-line flag without validation could allow unintended values (e.g., extremely small or huge numbers) that may cause denial of service or instability. start-selenium-grid-eventbus.sh [57-59] Referred Code if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi
	Unvalidated input Description: Unvalidated SE_EVENT_BUS_HEARTBEAT_PERIOD is forwarded to the process; lack of bounds checking may lead to resource exhaustion or misbehavior. start-selenium-grid-hub.sh [136-138] Referred Code if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi
	Unvalidated input Description: The heartbeat period environment variable is appended without validation; malicious or improper values could impact stability. start-selenium-standalone.sh [102-104] Referred Code if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi
	Unvalidated input Description: Forwarding SE_EVENT_BUS_HEARTBEAT_PERIOD directly to command args without validation may allow abusive values affecting availability. start-selenium-grid-docker.sh [72-74] Referred Code if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi
Ticket Compliance
⚪	🎫 No ticket provided - [ ] Create ticket/issue <!-- /create_ticket --create_ticket=true --> </details></td></tr>
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
⚪	No custom compliance provided Follow the guide to enable custom compliance check.

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
High-level	Enable the new heartbeat feature by default Set a default value for the new SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable in the Helm chart's values.yaml file. This will enable the new connection stability feature by default. Examples: Hub/start-selenium-grid-hub.sh [136-138] if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi EventBus/start-selenium-grid-eventbus.sh [57-59] if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi Solution Walkthrough: Before: # In charts/selenium-grid/values.yaml (conceptual) hub: # ... other configs env: - name: SOME_VAR value: "some_value" # SE_EVENT_BUS_HEARTBEAT_PERIOD is not configured, # so the feature is disabled by default for Helm users. eventBus: # ... other configs env: - name: SOME_OTHER_VAR value: "another_value" # SE_EVENT_BUS_HEARTBEAT_PERIOD is not configured. After: # In charts/selenium-grid/values.yaml (conceptual) hub: # ... other configs env: - name: SOME_VAR value: "some_value" - name: SE_EVENT_BUS_HEARTBEAT_PERIOD value: "60" # A sensible default value eventBus: # ... other configs env: - name: SOME_OTHER_VAR value: "another_value" - name: SE_EVENT_BUS_HEARTBEAT_PERIOD value: "60" # A sensible default value Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies that the new heartbeat feature, a key part of the PR, is not enabled by default in the Helm chart, which limits its immediate benefit for users.	Medium
Possible issue	Validate environment variable is positive Validate that the SE_EVENT_BUS_HEARTBEAT_PERIOD environment variable is a positive integer, not just a non-empty string, to prevent invalid values from being passed to the Selenium Grid. EventBus/start-selenium-grid-eventbus.sh [57-59] -if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then +if [[ "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" =~ ^[1-9][0-9]*$ ]]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi Apply / Chat Suggestion importance[1-10]: 6 __ Why: The suggestion correctly identifies a lack of input validation for the SE_EVENT_BUS_HEARTBEAT_PERIOD variable and proposes a more robust check to ensure it is a positive integer, preventing potential runtime issues.	Low
Learned best practice	Quote and use -n in tests Use -n for non-empty checks and quote variables; prefer parameter expansion with defaults to avoid empty args. EventBus/start-selenium-grid-eventbus.sh [57-59] -if [ ! -z "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" ]; then +if [ -n "${SE_EVENT_BUS_HEARTBEAT_PERIOD:-}" ]; then append_se_opts "--eventbus-heartbeat-period" "${SE_EVENT_BUS_HEARTBEAT_PERIOD}" fi Apply / Chat Suggestion importance[1-10]: 6 __ Why: Relevant best practice - Harden shell scripts by properly quoting variable expansions in test expressions and arguments to handle spaces and special characters.	Low
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