deck: add base path plumbing and helper APIs by tsj-30 · Pull Request #576 · kubernetes-sigs/prow

tsj-30 · 2025-12-12T02:29:59Z

This change teaches Deck about a configurable base path so it can be served from a sub‑URL without breaking static assets, APIs, or Spyglass. It introduces the --base-path flag, wraps the HTTP mux so requests are stripped/prefixed appropriately, extends template helpers to emit base-aware links, and adds deckURL utilities for the front-end.
This fixes #376.

k8s-ci-robot · 2025-12-12T02:30:05Z

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k8s-ci-robot · 2025-12-12T02:30:09Z

Hi @tsj-30. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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tsj-30 · 2025-12-12T02:32:37Z

CC: @petr-muller , @matthyx
As suggested by Petr, I’ll break this down and raise smaller PRs to fix #376.

Amulyam24 · 2025-12-12T05:42:15Z

/ok-to-test

tsj-30 · 2026-01-02T06:16:08Z

/retest

tsj-30 · 2026-01-02T07:38:00Z

Hi @petr-muller ,
Can you PTAL?
Thanks 😄

tsj-30 · 2026-01-09T06:10:13Z

cc: @loispostula

loispostula · 2026-01-09T06:16:46Z

@tsj-30 I'm not sure how to test this, I'll try to get a local build working and check

tsj-30 · 2026-01-21T04:16:44Z

Hi @loispostula,
Did you get a chance to test this, I have completed some additional code changes and looking forward to submit a follow PR if this looks good and merged.
If you need any futher help from my side please let me know.
Thanks!

petr-muller · 2026-01-21T16:59:16Z

/cc
/hold

I have an in-flight review with some feedback, will post hopefully tomorrow

petr-muller

My main concern is how well this was tested on the current default case (path is "/")? If the new subpath functionality is not 100% then I don't mind because we can fix it as we go, but the one thing we need to prevent is breaking existing deployments.

Some comments inline

/hold cancel

petr-muller · 2026-01-21T16:51:59Z


 func gatherOptions(fs *flag.FlagSet, args ...string) options {
 	var o options
+	o.basePath = "/"


nit: this is redundant with setting a default on L192

Will modify this.

petr-muller · 2026-01-21T16:52:45Z

 }

 func (o *options) Validate() error {
+	o.basePath = normalizeBasePath(o.basePath)


seems redundant with doing the same in gatherOptions

petr-muller · 2026-01-24T08:21:24Z

+// withBasePath ensures that only requests that begin with the configured base path are handled
+// and that downstream handlers only see paths relative to that base path.
+func withBasePath(basePath string, handler http.Handler) http.Handler {
+	basePath = normalizeBasePath(basePath)


another normalizeBasePath call

petr-muller · 2026-01-24T17:12:31Z

+		"deckBasePath":     func() string { return o.basePath },
+		"deckPath":         func(p string) string { return o.absolutePath(p) },


How are these consumed?

deckPath is used throughout the templates to prefix links/static asset URLs and nav links.
deckBasePath is used in base.html to set window.prowBasePath. That gets consumed in the frontend JS helpers in urls.ts

petr-muller · 2026-01-24T17:25:02Z

+// absolutePath returns the absolute URL path for a given relative path by prepending the
+// configured base path. The input is expected to be either "/" or begin with a slash.
+func (o options) absolutePath(rel string) string {
+	if rel == "" {
+		return ""
+	}
+
+	pathPart := rel
+	suffix := ""
+	if idx := strings.IndexAny(rel, "?#"); idx >= 0 {
+		pathPart = rel[:idx]
+		suffix = rel[idx:]
+	}
+	if pathPart == "" {
+		pathPart = "/"
+	}
+	if !strings.HasPrefix(pathPart, "/") {
+		pathPart = "/" + pathPart
+	}
+	if o.basePath == "/" {
+		return pathPart + suffix
+	}
+	if pathPart == "/" {
+		return o.basePath + suffix
+	}
+	return o.basePath + pathPart + suffix
+}


It's not easy to reason about all path manipulation possibilities, I'd like to have unit tests (also for stripBasePath and normalizeBasePath both to make sure they are correct and to serve as examples of what gets transformed to what.

Makes sense — I’ll add unit tests for stripBasePath and normalizeBasePath (including tricky slash + ./.. cases) so we verify correctness and document expected transformations. Will push the code as part of this PR.

petr-muller · 2026-01-24T17:28:31Z

+
+// absolutePath returns the absolute URL path for a given relative path by prepending the
+// configured base path. The input is expected to be either "/" or begin with a slash.
+func (o options) absolutePath(rel string) string {


This technically only needs to basePath from options, could the field be a custom string type and the methods would be defined on that? It would make the interface more narrow.

Yes, that’s possible. I can refactor this so it only depends on options.basePath: introduce a basePath custom string type and move absolutePath (and related helpers) onto it. I’ll push the change as well.

k8s-ci-robot · 2026-04-08T16:13:35Z

@tsj-30: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-prow-unit-test	`61dfbb1`	link	true	`/test pull-prow-unit-test`
pull-prow-verify-lint	`61dfbb1`	link	true	`/test pull-prow-verify-lint`
pull-prow-unit-test-race-detector-nonblocking	`61dfbb1`	link	false	`/test pull-prow-unit-test-race-detector-nonblocking`
pull-prow-integration	`61dfbb1`	link	true	`/test pull-prow-integration`

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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tsj-30 · 2026-04-09T03:26:52Z

Fix type error in templates_test.go by adding proper fakeConfigAgent

Fix template function call in base.html (remove printf wrapper)
Update test expectations to match actual output

Fixes linting failure in pull-prow-verify-lint check.

k8s-ci-robot added the area/deck Issues or PRs related to prow's deck component label Dec 12, 2025

k8s-ci-robot requested review from michelle192837 and smg247 December 12, 2025 02:30

k8s-ci-robot added cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Dec 12, 2025

k8s-ci-robot added the size/L Denotes a PR that changes 100-499 lines, ignoring generated files. label Dec 12, 2025

k8s-ci-robot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Dec 12, 2025

tsj-30 mentioned this pull request Jan 9, 2026

REQUEST: New membership for tsj-30 kubernetes/org#6051

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kishen-v reviewed Jan 21, 2026

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Comment thread cmd/deck/basepath.go Outdated

deck: add base path plumbing and helper APIs

76f5dfc

tsj-30 force-pushed the subpath_prow branch from bbc4aa5 to 76f5dfc Compare January 21, 2026 04:48

Update year in basepath.go

5204a98

k8s-ci-robot requested a review from petr-muller January 21, 2026 16:59

k8s-ci-robot added the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Jan 21, 2026

petr-muller reviewed Jan 24, 2026

View reviewed changes

k8s-ci-robot removed the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Jan 24, 2026

tsj-30 and others added 2 commits April 8, 2026 17:38

Merge branch 'kubernetes-sigs:main' into subpath_prow

9fe46d9

resolve linting errors in templates_test.go and base.html

61dfbb1

		"deckBasePath": func() string { return o.basePath },
		"deckPath": func(p string) string { return o.absolutePath(p) },

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