PCA Exporters & Instrumentation Flashcards
6 cards from real PCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 PCA Exporters & Instrumentation flashcards as text
What is a key drawback of using the Prometheus Pushgateway for all metrics collection?
Answer: It can serve stale metrics from jobs that have already finished, masking failures
Once metrics are pushed, the Pushgateway retains them indefinitely until explicitly deleted, so Prometheus may keep scraping old values from finished or failed jobs.
What does the `_bucket` suffix on a Histogram metric represent?
Answer: A cumulative count of observations that fall at or below each configured upper bound (le label)
Each _bucket series has an le (less than or equal) label representing an upper bound; its value is the cumulative count of observations at or below that bound.
In Prometheus client library instrumentation, what does a `Labels()` call on a metric vector do?
Answer: Returns a concrete metric instance with the specified label values, creating it if it doesn't exist
Calling Labels() (or With() in some libraries) on a metric vector returns the specific metric instance for that label combination, registering it in the registry if new.
What is the OpenMetrics format and how does it relate to Prometheus exposition format?
Answer: OpenMetrics is a standardized evolution of Prometheus exposition format with additional features, published as an IETF standard
OpenMetrics is a standardized specification based on the Prometheus text format, adding features like exemplars and becoming an IETF Internet Standard.
Which cAdvisor metric prefix is commonly used to expose container CPU and memory metrics to Prometheus?
Answer: container_
cAdvisor exposes container resource usage metrics with the container_ prefix, such as container_cpu_usage_seconds_total and container_memory_usage_bytes.
What is the purpose of a Prometheus `Collector` interface in client libraries?
Answer: It allows custom metric sources to register and describe their metrics dynamically rather than declaring them statically
The Collector interface lets you implement custom metric collection logic where metric descriptors and values are generated dynamically at scrape time.