Containeriserede applikationer har brug for centraliseret logging og monitoring, fordi containere er kortlivede og talrige — logs og metrics skal indsamles eksternt, så de overlever containerfjernelse og giver indsigt på tværs af hele systemet. Dette er essentiel observabilitet for produktionscontainere.
Logging: log til stdout/stderr, aggreger centralt
BEST PRACTICE: containers should log to STDOUT/STDERR (not to files inside the container):
→ Docker captures these (`docker logs`); a logging DRIVER forwards them elsewhere
→ WHY: containers are EPHEMERAL — logs in a removed container are LOST. Centralize them.
Logging drivers / pipelines forward logs to a central system:
→ json-file (default), syslog, fluentd, awslogs, gelf, etc. (--log-driver)
→ Aggregation stacks: ELK/Elastic (Elasticsearch+Logstash+Kibana), Loki+Grafana,
cloud logging (CloudWatch, Stackdriver), Datadog, etc.
→ Centralized logs: searchable, persistent, span ALL containers/hosts → real visibility
