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Cloud · head to head

Thanos vs Cilium

Thanos logo

Thanos

Cloud

Highly available Prometheus with long-term object storage

From
Free
Rated
-
Full reviewWebsite
Cilium logo

Cilium

Cloud

eBPF-based networking, observability and security for Kubernetes

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Thanos several components — sidecar, store, querier, compactor, ruler — each with its own configuration and failure modes; Cilium requires a recent Linux kernel, which rules out older distributions and some managed environments
  • They diverge on capability: Thanos covers Global query, Cilium covers eBPF datapath.

Where they differ

Only the attributes on which Thanos and Cilium actually diverge.

Attributes where Thanos and Cilium differ
AttributeThanosCilium
PlatformsKubernetes, Linux, DockerKubernetes, Linux

Identical on both: starting price (Free), pricing model (Open source, no licence fee), free tier (Yes), user rating (Not yet rated), category (Cloud).

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 Thanos

  • Global query
  • Object storage retention
  • Deduplication
  • Downsampling

Only in Cilium

  • eBPF datapath
  • Identity-based policy
  • Hubble observability
  • Sidecar-free mesh

What people use each for

The jobs each tool is most often brought in to do.

Thanos

  • Querying metrics across many clusters or regions from one placenot Cilium
  • Retaining metrics for years without local disk growthnot Cilium
  • Removing the gap that appears when a single Prometheus instance restartsnot Cilium

Cilium

  • Kubernetes networking at a scale where iptables-based CNI performance degradesnot Thanos
  • Network policy expressed on workload identity rather than fragile IP rulesnot Thanos
  • Seeing which services actually talk to each other, and what policy is droppingnot Thanos

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Thanos

  • Several components — sidecar, store, querier, compactor, ruler — each with its own configuration and failure modes
  • The compactor is a common source of operational trouble and must not run twice against the same bucket
  • Query latency over object storage is meaningfully higher than local Prometheus
  • Object storage costs and API request charges become real at high volume

Cilium

  • Requires a recent Linux kernel, which rules out older distributions and some managed environments
  • eBPF is genuinely hard to debug when it misbehaves, and the skill is rare on most teams
  • Broad scope — CNI, policy, mesh, observability — means the learning curve covers several domains at once

Pricing, plan by plan

Thanos

Free
  • ThanosFree
    • Full functionality
    • No usage limits
    • Community support

Cilium

Free
  • CiliumFree
    • Full functionality
    • No usage limits
    • Community support

Which should you pick?

Choose Thanos if

  • You need global query.
  • You want to start without paying.
  • You work on Kubernetes, Linux, Docker.
  • You also want object storage retention.
Thanos review

Choose Cilium if

  • You need ebpf datapath.
  • You want to start without paying.
  • You work on Kubernetes, Linux.
  • You also want identity-based policy.
Cilium review

Questions people ask

Is Thanos or Cilium better?
Neither clearly leads. Thanos starts at Free and Cilium at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Thanos or Cilium?
Thanos starts at Free and Cilium at Free.
Does Thanos or Cilium run on more platforms?
Thanos runs on Kubernetes, Linux, Docker. Cilium runs on Kubernetes, Linux.
Can I use Thanos for free?
Both have a free tier, so you can try either at no cost before committing.
What is Thanos best used for?
Thanos is most often used for querying metrics across many clusters or regions from one place, retaining metrics for years without local disk growth, removing the gap that appears when a single prometheus instance restarts. Of those, querying metrics across many clusters or regions from one place and retaining metrics for years without local disk growth are not what Cilium is typically brought in for.
What can Thanos do that Cilium cannot?
Thanos covers Global query, Object storage retention, Deduplication, Downsampling. Cilium covers eBPF datapath, Identity-based policy, Hubble observability, Sidecar-free mesh.

Answered from the vendors’ own pages

Thanos: Is Thanos free?

Yes, open source and CNCF-incubating. Costs are the object storage it uses.

Cilium: Is Cilium free?

Yes, open source and CNCF-graduated. Isovalent sells an enterprise distribution and support.

Thanos: Does Thanos replace Prometheus?

No. It runs alongside existing Prometheus servers, adding global query, deduplication and long-term storage.

Cilium: What does eBPF change?

It lets Cilium run packet-processing programs inside the kernel instead of relying on iptables rule chains, which behave poorly as the number of services grows.

Thanos: Thanos or VictoriaMetrics?

Thanos layers onto Prometheus using object storage and is the more established multi-cluster answer. VictoriaMetrics is a separate store aiming at lower resource use and fewer moving parts.

Cilium: Does Cilium replace a service mesh?

It can cover much of what a mesh does without sidecars, though full mesh feature sets still favour Istio or Linkerd.

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