Grafana Loki vs Logstash

Grafana Loki is a free, AGPLv3-licensed log aggregation system for storing and querying application and infrastructure logs. It can be self-hosted on Linux or accessed through Grafana Cloud Logs plans, with API support and live log tailing. Loki scales horizontally, supports high availability and multiple tenants, and indexes labels instead of log-line contents. LogQL provides queries in Grafana or the LogCLI command-line tool. Grafana describes object-storage support for high-throughput, durable, petabyte-scale retention. Loki can evaluate alerting rules on incoming logs and send results to Prometheus Alertmanager, with native integrations for Prometheus, Grafana, and Kubernetes. Documented ingestion options include Grafana Alloy, OpenTelemetry, Kubernetes Monitoring Helm, Docker, Fluent Bit, Fluentd, and Logstash. Installation methods include Helm, Tanka, Docker, Docker Compose, local installation, and source builds. Cloud plans range from free to paid Pro and Enterprise options.

Logstash is an open-source, server-side pipeline that collects data from many sources, transforms events, and sends results to destinations. It can continuously ingest logs, metrics, web application data, data-store information, and AWS service data. Filters parse events, identify fields, and transform content with features such as grok parsing, IP geolocation, and anonymizing or excluding sensitive fields. Data can go to multiple outputs, including Elasticsearch. Its plugin framework includes more than 200 input, filter, and output plugins, and custom plugins can be built with an API and generator. Persistent queues provide at-least-once delivery for in-flight events after node failures; dead letter queues retain events for inspection and replay. Monitoring tools show pipeline performance and availability. Logstash supports log pipelines, archive export, live tailing, and structured parsing. It is self-hosted, with Linux packages and Docker listed. The free plan is free under the Elastic License.