What's changed: Created Professional Cloud DevOps Engineer Chapter 4 (Domain 4 "Observability": Ops Agent/OpenTelemetry/Managed Service for Prometheus/Cloud Audit Logs/VPC Flow Logs, log optimization, synthetic monitors, log-based metrics, Logs Explorer, BigQuery/Pub/Sub/Cloud Storage export, PII/PHI redaction; Metrics Explorer/PromQL dashboards/alerting policies/PagerDuty, distributed tracing Cloud Trace/OpenTelemetry, trace-log correlation, troubleshooting).
4.1Instrumenting telemetry and managing logs
Understand collecting logs/metrics (Ops Agent, OpenTelemetry, Cloud Audit Logs, VPC Flow Logs, Google Cloud Managed Service for Prometheus), log optimization (filter/sampling/exclusions/cost), synthetic monitors, custom/log-based metrics, the Logs Explorer and query language, log export/retention (BigQuery/Pub/Sub/Cloud Storage), and redacting PII/PHI.
Observability means making a system’s internal state observable from outside. Instrument and collect the three pillars (logs, metrics, traces); start by laying the foundation for logs and metrics.
4.1.1Collecting telemetry and synthetic monitors
Collect VM logs/metrics with the Ops Agent and use OpenTelemetry for vendor-neutral instrumentation. Gather Prometheus-format metrics in a managed way via Google Cloud Managed Service for Prometheus. Audit via Cloud Audit Logs; network via VPC Flow Logs. Optimize logs with filtering/sampling/exclusions to control cost. Create app-specific signals as custom metrics or log-based metrics, and probe endpoints actively with synthetic monitors. Map "collect from VMs = Ops Agent" and "managed Prometheus = Managed Service for Prometheus."
4.1.2Analyzing, exporting, and protecting logs
Search and analyze logs with the Logs Explorer and the Logging query language. For retention/analysis, export/retain via sinks to BigQuery (SQL analysis)/Pub/Sub (integration)/Cloud Storage (cheap retention). Redact PII and PHI with log processors before storing. Map "SQL-analyze logs = export to BigQuery" and "cheap long-term retention = Cloud Storage."
Common: requirement → means. E.g., "collect VM logs/metrics" = Ops Agent; "vendor-neutral instrumentation" = OpenTelemetry; "managed Prometheus" = Managed Service for Prometheus; "SQL-analyze logs" = export to BigQuery; "make a metric from logs" = log-based metrics; "actively probe endpoints" = synthetic monitors; "strip PII from logs" = redaction via log processors.
Watch the mix-ups: (1) Choose log destinations by use: BigQuery (analysis)/Pub/Sub (integration)/Cloud Storage (cheap retention). (2) Optimize log cost via filtering/exclusions (storing everything is costly). (3) Redact PII/PHI before storing.
4.1.3Section summary
- Collect = Ops Agent/OpenTelemetry/Managed Service for Prometheus; audit = Cloud Audit Logs; external = synthetic monitors
- Analyze logs via Logs Explorer/query language; optimize cost with filtering/exclusions; create log-based metrics
- Export = BigQuery (analysis)/Pub/Sub (integration)/Cloud Storage (cheap retention); redact PII/PHI before storing
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Quick check
(just a quick review)Q1. To collect logs and metrics from Compute Engine VMs, which is best?
Q2. To collect/store Prometheus-format metrics in a managed way without self-hosting, which is best?
Q3. To flexibly analyze large logs with SQL, which export destination is best?
Q4. To treat occurrences of specific log entries as a time-series metric, which is best?
Q5. To proactively probe endpoints/workflows from the user’s perspective on a schedule, which is best?
Q6. To cut log ingestion cost while keeping important logs, which measure is best?
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