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Cybersecurity · head to head

Cosign vs Dokku

Cosign logo

Cosign

Cybersecurity

Signs and verifies container images and artifacts, with or without managing keys

From
Free
Rated
-
Full reviewWebsite
Dokku logo

Dokku

Cloud

Single-server platform that accepts a git push and runs Heroku buildpacks on Docker

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Cosign keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.; Dokku one maintainer accounts for nearly all human commit activity and the project records roughly 10,500 US dollars of annual income on Open Collective, which is not enough to fund a maintainer, so continuity rests on one person continuing to volunteer.
  • They diverge on capability: Cosign covers Keyless signing, Dokku covers Git push deploy.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Cosign and Dokku actually diverge.

Attributes where Cosign and Dokku differ
AttributeCosignDokku
PlatformsmacOS, Linux, Windows, DockerLinux, Docker, CLI, Self-hosted
CategoryCybersecurityCloud

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

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 Cosign

  • Keyless signing
  • Key and KMS signing
  • Registry-native storage
  • In-toto attestations
  • Offline verification
  • Trusted root and signing config

Only in Dokku

  • Git push deploy
  • Heroku buildpacks
  • Datastore plugins
  • Automatic certificates
  • Zero downtime deploys
  • Pluggable schedulers

What people use each for

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

Cosign

  • Signing container images in a build pipeline without managing long-lived private keysnot Dokku
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot Dokku
  • Meeting a customer or regulatory requirement for signed artifactsnot Dokku
  • Verifying third-party images before they enter an internal registrynot Dokku

Dokku

  • Running a dozen side projects and client applications on one virtual private server with Heroku style deploymentnot Cosign
  • Moving off a managed platform when the monthly bill has grown faster than the traffic hasnot Cosign
  • A consultancy that wants buildpack deployments without teaching every client team Kubernetesnot Cosign
  • Keeping a legacy Procfile application alive on hardware you control after a managed platform deprecates its stacknot Cosign

Where each one falls short

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

Cosign

  • Keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.
  • A signature proves who signed, never whether they should have. The documentation is explicit that Sigstore cannot determine authorisation, so every consumer must write and maintain their own identity and issuer policy or verification means nothing.
  • Nothing is enforced without an admission controller. Signing changes what you can prove, not what runs, and the official policy controller has a small maintainer base for a component sitting in a cluster admission path.
  • Upgrades break pipelines. Version 3 changed defaults, version 4 is announced as removing legacy functionality and roughly half the command line flags, and two official client libraries still lacked support for the new log format as of mid 2026.
  • Signatures do not expire. An artifact signed before a maintainer account was compromised and one signed after are indistinguishable unless somebody is actively monitoring the transparency log, and almost nobody is.

Dokku

  • One maintainer accounts for nearly all human commit activity and the project records roughly 10,500 US dollars of annual income on Open Collective, which is not enough to fund a maintainer, so continuity rests on one person continuing to volunteer.
  • Dokku Pro asks 849 US dollars for a lifetime licence from a project with no disclosed legal entity behind the promise and no published refund terms, while the product is still described as in development at early bird pricing.
  • Dokku is single-server by design, and the k3s scheduler that provides multi-node support is missing log retrieval, process inspection and content-based health checks, with a post-run hook the documentation says does not consistently fire.
  • Supported operating systems are limited to Ubuntu 22.04 or 24.04 and Debian 11 or later, so organisations standardised on Red Hat, Rocky or Alma Linux cannot run it on their approved base image.
  • Backups are separate commands per datastore plugin that you schedule yourself, with no unified snapshot, no point-in-time recovery and no tested restore path, so verifying that a restore works is entirely your responsibility.

Pricing, plan by plan

Cosign

Free
  • CosignFree
    • Apache-2.0
    • Public Sigstore infrastructure free to use
    • No usage limits published

Dokku

Free
  • DokkuFree
    • MIT licensed, no usage limits
    • Command line and SSH only
    • All datastore and certificate plugins
  • Dokku Pro$849/one-time
    • Lifetime licence with free upgrades and no subscription
    • Covers 1 production and 2 pre-production servers
    • Web dashboard and JSON REST API

Which should you pick?

Choose Cosign if

  • You need keyless signing.
  • You want to start without paying.
  • You work on macOS, Linux, Windows, Docker.
  • You also want key and kms signing.
Cosign review

Choose Dokku if

  • You need git push deploy.
  • You want to start without paying.
  • You work on Linux, Docker, CLI, Self-hosted.
  • You also want heroku buildpacks.
Dokku review

Questions people ask

Is Cosign or Dokku better?
Neither clearly leads. Cosign starts at Free and Dokku at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cosign or Dokku?
Cosign starts at Free and Dokku at Free.
Does Cosign or Dokku run on more platforms?
Cosign runs on macOS, Linux, Windows, Docker. Dokku runs on Linux, Docker, CLI, Self-hosted.
Can I use Cosign for free?
Both have a free tier, so you can try either at no cost before committing.
What is Cosign best used for?
Cosign is most often used for signing container images in a build pipeline without managing long-lived private keys, attaching a signed bill of materials to a release so consumers can verify its provenance, meeting a customer or regulatory requirement for signed artifacts, verifying third-party images before they enter an internal registry. Of those, signing container images in a build pipeline without managing long-lived private keys and attaching a signed bill of materials to a release so consumers can verify its provenance are not what Dokku is typically brought in for.
What can Cosign do that Dokku cannot?
Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Dokku covers Git push deploy, Heroku buildpacks, Datastore plugins, Automatic certificates.

Answered from the vendors’ own pages

Cosign: Does Cosign tell me if an image is vulnerable?

No. It has no vulnerability knowledge whatsoever. It can carry an SBOM as a signed attestation but never reads it. Pair it with a scanner.

Dokku: Is Dokku still maintained?

Yes. Version 0.38.27 shipped in August 2026 with roughly six releases in the preceding two months. The caveat is that one maintainer writes nearly all of it.

Cosign: Is signing alone enough?

No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.

Dokku: What does Dokku Pro give me over the free edition?

A web dashboard, a JSON REST API, git push over HTTPS, browser log tailing, team management and email support from the maintainers. It costs 849 US dollars once for one production and two pre-production servers.

Cosign: What does a bare cosign verify actually prove?

Very little. Without a pinned certificate identity and OIDC issuer, it accepts a valid signature from any identity at all.

Dokku: Can Dokku run across multiple servers?

Only through the k3s or Nomad schedulers. The k3s path is missing several commands and health check types, and the older Kubernetes scheduler is deprecated and no longer developed.

Cosign: What is the risk of keyless signing?

Your OIDC provider becomes the root of trust. Compromise of that account yields genuine, verifiable signatures, so account security is the control that matters.

Dokku: Will my Heroku application run on it unchanged?

Usually. Dokku runs the same buildpacks and reads a Procfile, so the application layer normally moves across. Add-ons, scaling behaviour and backups are the parts you have to rebuild.

Cosign: Should we expect breaking changes?

Yes. Version 4 is announced to remove roughly half the flags, and a post-quantum migration is named as a further breaking change after that.

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