Software · head to head
CloudWatch vs Fluentd
The short version
- Each has a real cost: CloudWatch the free tier covers 5 GB of log ingestion and 10 custom metrics a month, after which log ingestion is $0.50 per GB from 5 to 30 GB; Fluentd fluentd needs more than 60 MB of memory at runtime, against roughly 450 KB for Fluent Bit
- They diverge on capability: CloudWatch covers Metrics collection, Fluentd covers Log collection.
Where they differ
Only the attributes on which CloudWatch and Fluentd actually diverge.
| Attribute | CloudWatch | Fluentd |
|---|---|---|
| Pricing model | usage-based | open-source |
| Founded | 2006 | 2011 |
Identical on both: starting price (Free), free tier (Yes), platforms (Web, Api), user rating (Not yet rated), category (Unknown).
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 CloudWatch
- Metrics collection
- Log aggregation
- Dashboards
- Alarms and notifications
Only in Fluentd
- Log collection
- Data parsing
- Filtering and buffering
- Event routing
Both cover
- API
- Webhooks
- REST
- Web support
- Api support
What people use each for
The jobs each tool is most often brought in to do.
CloudWatch
- Metrics and log collection for AWS workloadsnot Fluentd
- Alarming on thresholds across AWS servicesnot Fluentd
- Querying logs with Logs Insightsnot Fluentd
- Live tailing logs during an incidentnot Fluentd
- Distributed tracing alongside X-Raynot Fluentd
Fluentd
- Unified log collection and routing from many sources to many destinationsnot CloudWatch
- Parsing and transforming log records before forwardingnot CloudWatch
- Aggregating logs from containers into Elasticsearch, S3 or a SIEMnot CloudWatch
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
CloudWatch
- The free tier covers 5 GB of log ingestion and 10 custom metrics a month, after which log ingestion is $0.50 per GB from 5 to 30 GB
- Custom metrics are $0.30 each for the first 10,000, so instrumenting broadly gets expensive before volume discounts apply
- Each custom dashboard beyond the free three is $3 a month
- Alarms are billed at $0.10 per alarm metric a month, with high-resolution alarms costing more
- Log storage beyond the free 5 GB is $0.03 per GB per month on top of the ingestion charge
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
CloudWatch
Free- FreeFree
- Metrics collection
- Log aggregation
- Dashboards
Fluentd
Free- FreeFree
- Log collection
- Data parsing
- Filtering and buffering
Which should you pick?
Choose CloudWatch if
- You need metrics collection.
- You want to start without paying.
- You work on Web, Api.
- You also want log aggregation.
Choose Fluentd if
- You need log collection.
- You want to start without paying.
- You work on Web, Api.
- You also want data parsing.
Questions people ask
- Is CloudWatch or Fluentd better?
- Neither clearly leads. CloudWatch 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, CloudWatch or Fluentd?
- CloudWatch starts at Free and Fluentd at Free.
- Does CloudWatch or Fluentd run on more platforms?
- Both run on Web, Api, so platform support will not decide this one for you.
- Can I use CloudWatch for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is CloudWatch best used for?
- CloudWatch is most often used for metrics and log collection for aws workloads, alarming on thresholds across aws services, querying logs with logs insights, live tailing logs during an incident. Of those, metrics and log collection for aws workloads and alarming on thresholds across aws services are not what Fluentd is typically brought in for.
- What can CloudWatch do that Fluentd cannot?
- CloudWatch covers Metrics collection, Log aggregation, Dashboards, Alarms and notifications. Fluentd covers Log collection, Data parsing, Filtering and buffering, Event routing. Both handle API, Webhooks, REST, Web support.