Log Management · head to head
Azure Monitor vs Fluentd
Azure Monitor
Log Management
Azure's Monitoring and Diagnostics Service
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Azure Monitor billed per GB ingested across three separate log plans, Auxiliary, Basic and Analytics, so the plan chosen changes the rate as much as the volume does; Fluentd fluentd needs more than 60 MB of memory at runtime, against roughly 450 KB for Fluent Bit
- They diverge on capability: Azure Monitor covers Metrics collection, Fluentd covers Data parsing.
Where they differ
Only the attributes on which Azure Monitor and Fluentd actually diverge.
| Attribute | Azure Monitor | Fluentd |
|---|---|---|
| Pricing model | usage-based | open-source |
| Founded | 2010 | 2011 |
Identical on both: starting price (Free), free tier (Yes), platforms (Web, Api), user rating (Not yet rated), category (Log Management).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Azure Monitor
- Metrics collection
- Alerts and notifications
- Custom dashboards
Only in Fluentd
- Data parsing
- Filtering and buffering
- Event routing
Both cover
- Log collection
- API
- Webhooks
- REST
- Web support
- Api support
What people use each for
The jobs each tool is most often brought in to do.
Azure Monitor
- Collecting logs and metrics from Azure resourcesnot Fluentd
- Alerting on metric thresholds and log queriesnot Fluentd
- Application performance monitoring through Application Insightsnot Fluentd
- Long-term log retention for compliancenot Fluentd
- Querying operational data with KQLnot Fluentd
Fluentd
- Unified log collection and routing from many sources to many destinationsnot Azure Monitor
- Parsing and transforming log records before forwardingnot Azure Monitor
- Aggregating logs from containers into Elasticsearch, S3 or a SIEMnot Azure Monitor
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Azure Monitor
- Billed per GB ingested across three separate log plans, Auxiliary, Basic and Analytics, so the plan chosen changes the rate as much as the volume does
- Only the first 5 GB a month of Analytics logs is free per billing account
- Retention beyond the base period is charged per GB per month, up to 2 years interactive and 12 years long term
- Log queries and search jobs are billed per GB scanned, so investigating an incident costs money
- Alert rules are billed per time series for metrics and by execution frequency for logs
- The pricing page shows placeholders rather than rates until a region and currency are chosen
Fluentd
- Fluentd needs more than 60 MB of memory at runtime, against roughly 450 KB for Fluent Bit
- Fluentd is built as a Ruby gem and depends on other gems, so a Ruby runtime is required
- Its capability comes from over 1,000 external plugins rather than built in functionality, so each added input or output is a separate dependency
- The Fluent Bit documentation states that cloud providers have switched from Fluentd to Fluent Bit for performance and compatibility and calls Fluent Bit the next generation solution
Pricing, plan by plan
Azure Monitor
Free- FreeFree
- Log collection
- Metrics collection
- Alerts and notifications
Fluentd
Free- FreeFree
- Log collection
- Data parsing
- Filtering and buffering
Which should you pick?
Choose Azure Monitor if
- You need metrics collection.
- You want to start without paying.
- You work on Web, Api.
- You also want alerts and notifications.
Choose Fluentd if
- You need data parsing.
- You want to start without paying.
- You work on Web, Api.
- You also want filtering and buffering.
Questions people ask
- Is Azure Monitor or Fluentd better?
- Neither clearly leads. Azure Monitor starts at Free and Fluentd at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Azure Monitor or Fluentd?
- Azure Monitor starts at Free and Fluentd at Free.
- Does Azure Monitor or Fluentd run on more platforms?
- Both run on Web, Api, so platform support will not decide this one for you.
- Can I use Azure Monitor for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Azure Monitor best used for?
- Azure Monitor is most often used for collecting logs and metrics from azure resources, alerting on metric thresholds and log queries, application performance monitoring through application insights, long-term log retention for compliance. Of those, collecting logs and metrics from azure resources and alerting on metric thresholds and log queries are not what Fluentd is typically brought in for.
- What can Azure Monitor do that Fluentd cannot?
- Azure Monitor covers Metrics collection, Alerts and notifications, Custom dashboards. Fluentd covers Data parsing, Filtering and buffering, Event routing. Both handle Log collection, API, Webhooks, REST.