NE-2418: Add haproxy_max_connections metric

[alebedev87]

Add a new haproxy_max_connections gauge metric that exposes the process-wide maximum connections configured for HAProxy.

The metric is extracted from the public frontend's "slim" field (field 6) in HAProxy's "show stat" CSV output. Since the router configures both global and defaults sections with the same ROUTER_MAX_CONNECTIONS value, the public frontend's session limit reflects the process-wide maxconn setting.

E2E test: openshift/cluster-ingress-operator#1361.

[openshift-ci-robot]

@alebedev87: This pull request references NE-2418 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.22.0" version, but no target version was set.

Details

In response to this:

Add a new haproxy_max_connections gauge metric that exposes the process-wide maximum connections configured for HAProxy.

The metric is extracted from the public frontend's "slim" field (field 6) in HAProxy's "show stat" CSV output. Since the router configures both global and defaults sections with the same ROUTER_MAX_CONNECTIONS value, the public frontend's session limit reflects the process-wide maxconn setting.

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[openshift-ci]

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[openshift-ci]

@alebedev87: all tests passed!

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[alebedev87]

The new e2e test from CIO is passing.

/retitle NE-2418: Add haproxy_max_connections metric

[openshift-ci-robot]

@alebedev87: This pull request references NE-2418 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.22.0" version, but no target version was set.

Details

In response to this:

Add a new haproxy_max_connections gauge metric that exposes the process-wide maximum connections configured for HAProxy.

The metric is extracted from the public frontend's "slim" field (field 6) in HAProxy's "show stat" CSV output. Since the router configures both global and defaults sections with the same ROUTER_MAX_CONNECTIONS value, the public frontend's session limit reflects the process-wide maxconn setting.

E2E test: openshift/cluster-ingress-operator#1361.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci-robot]

@alebedev87: This pull request references NE-2418 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.22.0" version, but no target version was set.

Details

In response to this:

Add a new haproxy_max_connections gauge metric that exposes the process-wide maximum connections configured for HAProxy.

The metric is extracted from the public frontend's "slim" field (field 6) in HAProxy's "show stat" CSV output. Since the router configures both global and defaults sections with the same ROUTER_MAX_CONNECTIONS value, the public frontend's session limit reflects the process-wide maxconn setting.

E2E test: openshift/cluster-ingress-operator#1361.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[jcmoraisjr]

/assign

[jcmoraisjr]

This metric is already available via haproxy_frontend_current_sessions, its just hidden behind this configuration, its missing 6:

router/pkg/router/metrics/haproxy/haproxy.go

Lines 109 to 111 in d8ed355

	// defaultSelectedMetrics is the list of metrics included by default. These metrics are a subset
	// of the metrics exposed by haproxy_exporter by default for performance reasons.
	var defaultSelectedMetrics = []int{2, 4, 5, 7, 8, 9, 13, 14, 17, 21, 24, 33, 35, 39, 40, 41, 42, 43, 44, 58, 59, 60, 79, 85}

Also, as you pointed this is a frontend metric. The global one is available via show info, and reading global metrics from there is preferable because it not only provides the correct one, but also provides the current global connections, which is the metric to be tracked along with maxconn to alert users about the availability of their connection limits.