Docs: Add external link validation with lychee

.github/workflows/docs-weekly.yml

@@ -0,0 +1,73 @@
+# Copyright 2026 The kpt Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Weekly documentation verification: spelling and external link checking.
+
+name: Docs Weekly
+on:
+  schedule:
+    - cron: '0 3 * * 1'  # Every Monday at 03:00 UTC
+  workflow_dispatch:      # Allow manual triggering
+
+jobs:
+  docs-verify:
+    name: docs-verify
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          submodules: true
+          fetch-depth: 0
+
+      - name: Set up Go
+        uses: actions/setup-go@v6
+        with:
+          go-version-file: documentation/go.mod
+          cache: false
+
+      - name: Get Hugo version
+        id: hugo-version
+        run: echo "version=$(grep -m1 'HUGO_VERSION' documentation/netlify.toml | cut -d'"' -f2)" >> "$GITHUB_OUTPUT"
+
+      - name: Set up Hugo
+        uses: peaceiris/actions-hugo@v3
+        with:
+          hugo-version: ${{ steps.hugo-version.outputs.version }}
+          extended: true
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v7
+        with:
+          node-version-file: documentation/package.json
+
+      - name: Install Node dependencies
+        working-directory: documentation
+        run: npm install
+
+      - name: Verify spelling
+        working-directory: documentation
+        run: make verify
+
+      - name: Build site
+        working-directory: documentation
+        run: make production-build
+
+      - name: Check external links
+        uses: lycheeverse/lychee-action@v2
+        with:
+          args: '-vv --config lychee.toml --root-dir public --extensions html public'
+          lycheeVersion: v0.24.2
+          fail: true
+          workingDirectory: documentation

README.md

@@ -24,7 +24,7 @@ scale by manipulating declarative Configuration as Data.
 
 See [the FAQ](https://kpt.dev/faq/) for more details about how kpt is different from alternatives.
 
-Use our [public Dosu space](https://github.dosu.com/kptdev/kpt) to ask anything about kpt.
+Use our [public Dosu space](https://app.dosu.dev/b19fb34f-d249-48ae-a3b1-2bd8ec156e41/ask) to ask anything about kpt.
 
 ## Why kpt?
 

documentation/Makefile

@@ -16,6 +16,11 @@ serve:
 verify:
 	go run github.com/golangci/misspell/cmd/misspell@v0.8.0 -error content/
 
+.PHONY: check-links-external
+check-links-external: production-build
+	@command -v lychee >/dev/null 2>&1 || { echo "Error: lychee not found. Install it from https://github.com/lycheeverse/lychee#installation"; exit 1; }
+	lychee -vv --config lychee.toml --root-dir public --extensions html public
+
 production-build:
 	git submodule update --init --recursive
 	git fetch --tags

documentation/README.md

@@ -33,6 +33,34 @@ The site pulls some dependencies via Git submodules. If `npm install` succeeds b
 git submodule update --init --recursive
 ```
 
+## Checking external links
+
+To validate external links in the documentation, use:
+
+```sh
+make check-links-external
+```
+
+This builds the site with Hugo and runs [lychee](https://github.com/lycheeverse/lychee) against the rendered HTML.
+
+### Prerequisites
+
+- **Hugo** — installed via `npm install` (from `devDependencies`) or [standalone](https://gohugo.io/installation/)
+- **lychee** — install via one of:
+  - macOS: `brew install lychee`
+  - Linux/macOS (Cargo): `cargo install lychee`
+  - Binary download: see [lychee releases](https://github.com/lycheeverse/lychee/releases)
+
+### Using a GitHub token
+
+To avoid GitHub rate limiting, pass a token:
+
+```sh
+GITHUB_TOKEN=$(gh auth token) make check-links-external
+```
+
+The token is only sent to github.com domains.
+
 ## Style guide for documentation
 
 1. Use US English in the documentation

documentation/content/en/_index.md

@@ -47,7 +47,7 @@ kpt is an open source project and anyone can [contribute](https://github.com/kpt
 To get familiar with kpt, the best way to start is with the first 4 chapters of the kpt [Book]({{% relref "book" %}}).
 Furthermore it is useful to check the [references]({{% relref "reference" %}}) and the catalog of [selected krm functions](https://catalog.kpt.dev).
 
-Use our [public Dosu space](https://github.dosu.com/kptdev/kpt) to ask anything about kpt.
+Use our [public Dosu space](https://app.dosu.dev/b19fb34f-d249-48ae-a3b1-2bd8ec156e41/ask) to ask anything about kpt.
 
 # For admins
 

documentation/content/en/book/01-getting-started/_index.md

@@ -30,7 +30,7 @@ configured.
 
 #### Docker
 
-Follow the [instructions](https://docs.docker.com/get-docker) to install and configure Docker.
+Follow the [instructions](https://docs.docker.com/get-started/get-docker/) to install and configure Docker.
 
 #### Podman
 

documentation/content/en/book/04-using-functions/_index.md

@@ -739,7 +739,7 @@ kpt fn eval wordpress -i kubeconform:latest --network -- schema_location="https:
 
 #### Mounting directories
 
-By default, the functions cannot access the host file system. You can use the `--mount` flag to mount the host volumes. kpt accepts the same options to `--mount`, as specified on the [Docker Volumes](https://docs.docker.com/storage/volumes/) page.
+By default, the functions cannot access the host file system. You can use the `--mount` flag to mount the host volumes. kpt accepts the same options to `--mount`, as specified on the [Docker Volumes](https://docs.docker.com/engine/storage/volumes/) page.
 
 The `kubeconform` function can, for example, consume a JSON schema file, as follows:
 

documentation/content/en/book/05-developing-functions/_index.md

@@ -127,7 +127,7 @@ for writing functions that manipulate KRM. Go provides:
 
 - [Install kpt]({{% relref "/installation/kpt-cli" %}})
 
-- [Install Docker](https://docs.docker.com/get-docker/)
+- [Install Docker](https://docs.docker.com/get-started/get-docker/)
 
 - [Golang](https://go.dev/dl/) (at least version 1.24)
 

documentation/content/en/book/07-effective-customizations/_index.md

@@ -326,7 +326,7 @@ The mutation pipeline fails because the Rego policy has been violated.
 When using template languages I am able to provide conditional statements based 
 on parameter values.  This allows me to ask the user for a little bit of 
 information and generate a lot of boilerplate configuration.  Some template 
-languages like [Jinja](https://palletsprojects.com/p/jinja/) are very robust and feature rich.
+languages like [Jinja](https://palletsprojects.com/projects/jinja/) are very robust and feature rich.
 
 ### Problems:
 

documentation/content/en/installation/migration.md

@@ -355,18 +355,18 @@ kpt `v0.39`) to `v1` version(compatible with kpt `v1.0`).
 
 [v0.39 commands]: https://kptdev.github.io/kpt/reference/
 [v1.0 commands]: /reference/cli/
-[v1 kptfile]: https://github.com/kptdev/kpt/blob/main/pkg/api/kptfile/v1/types.go
+[v1 kptfile]: https://github.com/kptdev/kpt/blob/main/api/kptfile/v1/types.go
 [starlark function]: https://catalog.kpt.dev/starlark/v0.2/
 [apply-setters]: https://catalog.kpt.dev/apply-setters/v0.1/
 [setter inheritance]: https://kptdev.github.io/kpt/concepts/setters/#inherit-setter-values-from-parent-package
 [openapi validations]: https://kptdev.github.io/kpt/guides/producer/setters/#openapi-validations
 [required setters]: https://kptdev.github.io/kpt/guides/producer/setters/#required-setters
 [auto-setters]: https://kptdev.github.io/kpt/concepts/setters/#auto-setters
 [migrating inventory objects]: https://kptdev.github.io/kpt/reference/live/alpha/
-[live migration]: https://kptdev.github.io/kpt/reference/cli/live/alpha/
+[live migration]: https://kptdev.github.io/kpt/reference/live/alpha/
 [configpath]: /book/04-using-functions/01-declarative-function-execution?id=configpath
-[example kpt package]: https://github.com/kptdev/krm-functions-catalog/tree/master/testdata/fix
-[simple example]: https://github.com/kptdev/krm-functions-catalog/tree/master/functions/go/fix#examples
+[example kpt package]: https://github.com/kptdev/krm-functions-catalog/tree/main/archived/functions/go/fix/testdata/fix
+[simple example]: https://github.com/kptdev/krm-functions-catalog/tree/main/archived/functions/go/fix#examples
 [function config]: /book/04-using-functions/01-declarative-function-execution?id=configpath
 [starlark runtime]: https://kptdev.github.io/kpt/guides/producer/functions/starlark/
 [update guide]: /book/03-packages/05-updating-a-package
@@ -377,6 +377,6 @@ kpt `v0.39`) to `v1` version(compatible with kpt `v1.0`).
 [installation instructions]: /installation/
 [install]: /installation/
 [kpt-functions-catalog]: https://catalog.kpt.dev/
-[v1alpha1 kptfile]: https://github.com/kptdev/kpt/blob/master/pkg/kptfile/pkgfile.go#L39
+[v1alpha1 kptfile]: https://github.com/kptdev/kpt/blob/v0/pkg/kptfile/pkgfile.go#L39
 [git clone]: https://git-scm.com/docs/git-clone
 [publish your package]: /book/03-packages/08-publishing-a-package

documentation/content/en/reference/cli/fn/eval/_index.md

@@ -322,5 +322,5 @@ $ KRM_FN_RUNTIME=podman kpt fn eval DIR -i ghcr.io/example.com/my-fn
 
 <!--mdtogo-->
 
-[docker volumes]: https://docs.docker.com/storage/volumes/
+[docker volumes]: https://docs.docker.com/engine/storage/volumes/
 [imperative function execution]: /book/04-using-functions/#imperative-function-execution

documentation/content/en/reference/schema/config-connector-status-convention/_index.md

@@ -8,11 +8,11 @@ menu:
     parent: "Schema Reference"
 ---
 
-`kpt` includes custom rules for [Config Connector](https://cloud.google.com/config-connector/docs/overview) resources to
+`kpt` includes custom rules for [Config Connector](https://docs.cloud.google.com/config-connector/docs/overview) resources to
 make them easier to work with. This document describes how kpt uses fields and conditions on Config Connector
 resources to compute [reconcile status]({{% relref "/book/06-deploying-packages#reconcile-status" %}}).
 
-[Config Connector](https://cloud.google.com/config-connector/docs/how-to/monitoring-your-resources) resources expose the
+[Config Connector](https://docs.cloud.google.com/config-connector/docs/how-to/monitoring-your-resources) resources expose the
 `observedGeneration` field in the status object, and `kpt` will always report a resource as being `InProgress` if the
 `observedGeneration` doesn't match the value of `metadata.generation`.
 
@@ -22,7 +22,7 @@ as `Current`, i.e it has been successfully reconciled.
 If the `Ready` condition is `False`, `kpt` will look at the `Reason` field on the
 condition object to determine whether the resource is making progress towards
 reconciliation. The possible values mirrors those used by
-[Config Connector events](https://cloud.google.com/config-connector/docs/how-to/monitoring-your-resources#viewing_events).
+[Config Connector events](https://docs.cloud.google.com/config-connector/docs/how-to/monitoring-your-resources#viewing_events).
 If the value is one of the following, the resource is considered to have failed
 reconciliation:
 - `ManagementConflict`

documentation/content/en/reference/schema/crd-status-convention/_index.md

@@ -10,7 +10,7 @@ menu:
 
 To enable kpt to calculate the [reconcile status]({{% relref "/book/06-deploying-packages#reconcile-status" %}}) for CRDs, this
 document provides additional conventions for status conditions following the
-[Kubernetes API Guideline](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md).
+[Kubernetes API Guideline](https://github.com/kubernetes/community/blob/main/contributors/devel/sig-architecture/api-conventions.md).
 Custom controllers should use the following conditions types to signal whether a resource has been fully reconciled, and
 whether it has encountered any problems:
 

documentation/layouts/partials/footer.html

@@ -93,8 +93,8 @@
 				kpt follows <a href="{{ .Site.Params.code_of_conduct }}" target="_blank" rel="noopener">The CNCF Code of Conduct</a> | 
 				This site was built with the <a href="https://www.docsy.dev/">Docsy</a> <a href="https://gohugo.io/">Hugo</a> 
 				theme and deployed to Netlify.</small>
-				<a href="https://www.netlify.com"> <img src="https://www.netlify.com/v3/img/components/netlify-color-bg.svg" alt="Deploys by Netlify" height="25"/> </a> </br>
-				For website terms of use, trademark policy and other project policies please see <a href="https://lfprojects.org/policies/">lfprojects.org/policies</a>. </br>
+				<a href="https://www.netlify.com"> <img src="https://www.netlify.com/assets/badges/netlify-badge-color-bg.svg" alt="Deploys by Netlify" height="25"/> </a> <br/>
+				For website terms of use, trademark policy and other project policies please see <a href="https://lfprojects.org/policies/">lfprojects.org/policies</a>. <br/>
 				The Linux Foundation has registered trademarks and uses trademarks. For a list of trademarks of The Linux Foundation, 
          please see our <a href="https://www.linuxfoundation.org/legal/trademark-usage">Trademark Usage page</a>.
 			{{ if not .Site.Params.ui.footer_about_disable }}

documentation/lychee.toml

@@ -0,0 +1,51 @@
+# Copyright 2026 The kpt Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# lychee configuration for external link validation.
+# See https://lychee.cli.rs for full documentation.
+#
+# Run: make check-links-external
+# With GitHub token (recommended): GITHUB_TOKEN=<token> make check-links-external
+
+# Only check http/https links.
+scheme = ["https", "http"]
+
+# Resolve root-relative links against the Hugo output directory.
+root_dir = "public"
+
+require_https = true
+timeout = 30
+max_retries = 3
+max_concurrency = 64
+accept_timeouts = true
+user_agent = "Mozilla/5.0 (compatible; kpt-link-checker; +https://kpt.dev)"
+
+# Exclude URLs from checking (regex patterns).
+exclude = [
+  # Slack requires authentication; always returns 403 to bots.
+  "^https://kubernetes\\.slack\\.com",
+  "^https://slack\\.k8s\\.io",
+  # GitHub org project boards require a browser session.
+  "^https://github\\.com/orgs/.*/projects/",
+  # Netlify intermittently blocks CI runners.
+  "^https://www\\.netlify\\.com",
+  # Docsy theme "Edit this page" and "Create issue" links always redirect to login.
+  "^https://github\\.com/kptdev/kpt/edit/",
+  "^https://github\\.com/kptdev/kpt/issues/new",
+]
+
+# Per-host rate limiting to avoid triggering abuse detection.
+[hosts."github.com"]
+concurrency = 1
+request_interval = "3s"