Build Linux ARM binaries in the CI

[jpraynaud]

Why

We want to provide pre-built binaries for Linux ARM in our GitHub releases.

This is a feature requested by the community (discord) and which follows-up with the issue #1751.

Important

Based on current usages of the CI, we evaluate that ~100,000 minutes will be needed for 12 months of a similar usage of the CI that we had for the last 12 months. We would need 5 ARM runners of type Linux 2-core or Linux 4-core We can use the ubuntu-24.04-arm runner available in public preview.

What

Update the CI to create a Linux ARM binary for the signer, clients and aggregator (if possible).

How

• Evaluate impact on the CI:
  • build times (see the results in the table in the comment below):
    • without cache
    • with cache
  • test times (see the results in the table in the comment below):
    • without cache
    • with cache
  • e2e tests if applicable
• Update the CI to use a Linux ARM runner (see):
  • signer
  • client
  • aggregator
  • relay
  • e2e tests if possible?
  • Create a platform support matrix - Mithril node vs platform - in the release note
  • Mention that the builds are not 'guaranteed' or 'use at own risk' in the release note
• Update the manual workflows in GitHub actions to test arm builds
• Update the pre release workflow in the CI
• Provide Docker images for ARM:
  • signer
  • client
  • aggregator
  • Update the release notes with a platform support table
• Deactivate the command tools utxo-hd snapshot converter in the client CLI for the Linux ARM platform
• Do not display the message at the end of a download explaining how to restart a Cardano node and how to convert a ledger state snapshot

Later

• How can we run the e2e tests in ARM without an ARM version of the Cardano distribution?

[dlachaume]

CI adaptation results so far:

Using the ubuntu-22.04-arm runner in the CI confirms that Mithril binaries and libraries can be built, and that unit and integration tests run successfully, without adding any significant overhead to the overall CI workflow execution time.

However, running the end-to-end test is currently not straightforward, as it requires an ARM-compatible Cardano node binary, which is not provided in the official Cardano node distributions. One possible solution would be to compile the Cardano node directly on the ARM runner, but this would significantly increase the overall CI execution time, which is not desirable.

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Build times

Runners	Ubuntu 22.04 arm64 (without build Tooling)	Ubuntu 22.04 arm64	Ubuntu 22.04 x64
Without cache	9m 40s	10m 46s	13m 45s
With cache	5m 29s	4m 56s	5m 13s

---

Test times

Runners	Ubuntu 24.04 arm64	Ubuntu 24.04 x64
Without cache	9m 15s	12m 37s
With cache	5m 55s	7m 24s

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Docker images build

Emulation with QEMU takes more time than native builds. In our case, it adds approximately 1 extra minute to the overall CI execution time when building multi-architecture Docker images (amd64 + arm64).