d277323b3e
In many cases we use the kolla_address filter to look up the IP address of the current host or another host on a particular network interface. This filter uses the host's facts to determine the IP, meaning that we must have gathered facts for the host, even if it is outside of a requested --limit. This is a limitation, since it requires that all hosts must be reachable, even if we are not directly configuring them. Most instances of this cross-host fact referencing involve a controller, since they host clustered services. The only instance found to affect compute nodes is in the prometheus role, where Prometheus server needs to know the IP address of all targets in its scrape configs. If we are able to specify the address of the scrape targets as a static variable such as a host variable, then facts would not be required for compute nodes outside of the --limit. Removing the requirement to have facts for all compute nodes has benefits for performance (gathering facts for all hosts can take a long time) and fault tolerance (we can operate when some compute hosts are unreachable). This change modifies the kolla_address filter to accept an optional override_var argument which can be used to specify the name of a host variable that may override the returned IP address. This is used in the Prometheus server configuration to allow specifying the IP address used by Prometheus server when collecting metrics from exporter using a 'prometheus_target_address' host variable. If specified, this takes precedence over the API interface address currently used. This makes it possible to statically override prometheus_target_address and avoid the cross-host fact reference. This is not a complete solution because it is not yet possible to skip the cross-host fact gathering step. Partial-Bug: #2041860 Change-Id: I207ca56362de00d8ec578333eab9e1a72e7bcd19
7 lines
213 B
YAML
7 lines
213 B
YAML
---
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features:
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Adds support for overriding the IP address used by Prometheus server to
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collect metrics from exporters. This is done by specifying
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``prometheus_target_address`` as a host variable.
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