feat(examples & workflows): Add prometheus3.5.3

[AlexiksA]

Add prometheus 3.5.3 example and Workflows.

[razvand]

Use present tense in the commit description. Also add more information in the commit description. Mention what are the contents of the commit.

[Copilot]

Pull request overview

Adds a new Prometheus 3.5.3 example for Unikraft Cloud, plus CI workflows to deploy and smoke-test the example in staging/stable environments.

Changes:

• Introduces prometheus3.5.3/ example assets (Kraftfile, Dockerfile, README, ignores).
• Adds GitHub Actions workflows to deploy the example and verify the /metrics endpoint in staging and stable.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
prometheus3.5.3/README.md	Usage guide for deploying/running the Prometheus example and customization notes
prometheus3.5.3/Kraftfile	Runtime/rootfs/port/volume configuration and Prometheus command flags
prometheus3.5.3/Dockerfile	Builds a minimal rootfs with the Prometheus 3.5.3 binary and default config
prometheus3.5.3/.gitignore	Ignores local Unikraft build artifacts
prometheus3.5.3/.dockerignore	Ignores local Unikraft build artifacts during docker builds
.github/workflows/example-prometheus3.5.3-staging.yaml	CI deploy + /metrics smoke test in staging
.github/workflows/example-prometheus3.5.3-stable.yaml	CI deploy + /metrics smoke test in stable

Suppressed comments (2)

prometheus3.5.3/README.md:177

• This Dockerfile explanation doesn't match the actual Dockerfile: the image copies prometheus.yml from the upstream release (via --from=build), not from a local prometheus.yml file.

* `COPY prometheus.yml /etc/prometheus/prometheus.yml`: Copy the Prometheus configuration file into the image.

prometheus3.5.3/README.md:181

• This suggests editing a local prometheus.yml, but the current Dockerfile pulls prometheus.yml from the upstream tarball, and there is no prometheus.yml in the repo. The customization instructions should describe how to supply an overridden config (e.g., add prometheus.yml to the repo and adjust the Dockerfile COPY).

* Update `prometheus.yml` to change scrape targets, intervals, alerting rules, or any other Prometheus configuration.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.

Suppressed comments (5)

Previously missed (4) — in code that hasn't changed since the last review.

prometheus3.5.3/README.md:51

• The README says Prometheus needs a volume for persistence, but the unikraft run example doesn’t mount the prometheus-data volume, so metrics will still be stored on ephemeral storage.

unikraft run --metro fra -p 443:9090/tls+http -m 1G --image <my-org>/prometheus:latest

prometheus3.5.3/README.md:155

• prometheus.yml is listed as a repository file to edit, but there is no prometheus3.5.3/prometheus.yml checked in (the Dockerfile extracts it from the upstream tarball). This makes the customization instructions misleading.

This issue also appears on line 175 of the same file.

* `Kraftfile`: the Unikraft Cloud specification
* `Dockerfile`: the Docker-specified app filesystem
* `prometheus.yml`: Prometheus configuration file (copied from the upstream Prometheus release; customize by providing your own file and updating the Dockerfile COPY line)

prometheus3.5.3/Kraftfile:7

• This Kraftfile uses the shorthand rootfs: ./Dockerfile, which is inconsistent with the rest of the repo’s examples that declare rootfs.source and set an explicit format: erofs (e.g. grafana/Kraftfile:5-7). Using the full form avoids relying on defaults and makes automated tooling more consistent.

rootfs: ./Dockerfile

prometheus3.5.3/Dockerfile:14

• The final image doesn’t install ca-certificates. That can break HTTPS scrapes/remote-write/alerting integrations which rely on the OS trust store, even if the /metrics endpoint itself is served over plain HTTP behind the platform TLS terminator.

# minimal rootfs
FROM alpine:3.19

COPY --from=build /tmp/prometheus-release/prometheus /bin/prometheus
COPY --from=build /tmp/prometheus-release/prometheus.yml /etc/prometheus/prometheus.yml

prometheus3.5.3/README.md:177

• This Dockerfile explanation doesn’t match the actual Dockerfile: the config is copied from the build stage (COPY --from=build .../prometheus.yml), not from a local prometheus.yml file.

* `COPY --from=build /tmp/prometheus-release/prometheus /bin/prometheus`: Copy only the Prometheus binary into the final image.

* `COPY prometheus.yml /etc/prometheus/prometheus.yml`: Copy the Prometheus configuration file into the image.