Show last-built timestamp + linked commit SHA in footer

gatsby-config.js

@@ -1,7 +1,10 @@
 require("dotenv").config()
 const { loadConfig } = require("./src/common")
+const { resolveGitCommit } = require("./src/resolveGitCommit")
 
 const config = loadConfig("./config.yaml", "./config.default.yaml")
+const gitCommit = resolveGitCommit() || ""
+const repositoryUrl = process.env.GATSBY_RESPOSITORY_URL || ""
 
 module.exports = {
   siteMetadata: {
@@ -16,6 +19,8 @@ module.exports = {
     searchableAttributes: config.searchableAttributes,
     customDomain: config.customDomain,
     failOnValidation: config.failOnValidation,
+    gitCommit,
+    repositoryUrl,
   },
   pathPrefix: `${process.env.BASEURL || ""}`,
   plugins: [

src/buildInfo.js

@@ -0,0 +1,16 @@
+function formatBuildTime(iso) {
+  if (!iso) return ""
+  return new Date(iso).toISOString().slice(0, 16).replace("T", " ") + " UTC"
+}
+
+function shortSha(sha) {
+  if (!sha) return ""
+  return sha.slice(0, 7)
+}
+
+function commitUrl(repositoryUrl, sha) {
+  if (!repositoryUrl || !sha) return ""
+  return `${repositoryUrl.replace(/\/$/, "")}/commit/${sha}`
+}
+
+module.exports = { formatBuildTime, shortSha, commitUrl }

src/components/footer.jsx

@@ -3,9 +3,15 @@ import PropTypes from "prop-types"
 import React from "react"
 
 import { getConfigAndConceptSchemes } from "../hooks/configAndConceptSchemes"
+import { commitUrl, formatBuildTime, shortSha } from "../buildInfo"
 
 const Footer = () => {
-  const { config } = getConfigAndConceptSchemes()
+  const { config, buildTime } = getConfigAndConceptSchemes()
+  const { repositoryUrl, gitCommit } = config
+
+  const formattedTime = formatBuildTime(buildTime)
+  const sha = shortSha(gitCommit)
+  const href = commitUrl(repositoryUrl, gitCommit)
 
   const style = css`
     background: ${config.colors.skoHubMiddleColor};
@@ -54,17 +60,28 @@ const Footer = () => {
     <footer css={style}>
       <div className="footerContent">
         <ul>
-          {process.env.GATSBY_RESPOSITORY_URL && (
+          {repositoryUrl && (
             <li>
-              <a
-                href={process.env.GATSBY_RESPOSITORY_URL}
-                target="_blank"
-                rel="noopener noreferrer"
-              >
+              <a href={repositoryUrl} target="_blank" rel="noopener noreferrer">
                 Source
               </a>
             </li>
           )}
+          {formattedTime && (
+            <li>
+              Last built: {formattedTime}
+              {sha && href && (
+                <>
+                  {" ("}
+                  <a href={href} target="_blank" rel="noopener noreferrer">
+                    {sha}
+                  </a>
+                  {")"}
+                </>
+              )}
+              {sha && !href && ` (${sha})`}
+            </li>
+          )}
           {links.map((link, idx) => (
             <li key={idx} className={idx === 0 ? "push-right" : ""}>
               <a

src/hooks/configAndConceptSchemes.js

@@ -34,16 +34,20 @@ import { useStaticQuery, graphql } from "gatsby"
  *     },
  *     searchableAttributes: string[],
  *     customDomain: string,
- *     failOnValidation: boolean
+ *     failOnValidation: boolean,
+ *     gitCommit: string,
+ *     repositoryUrl: string
  *   },
+ *   buildTime: string,
  *   conceptSchemes: Object<string, { languages: string[] }>
- * }} An object containing `config` and `conceptSchemes`
+ * }} An object containing `config`, `buildTime` and `conceptSchemes`
  *
  */
 export const getConfigAndConceptSchemes = () => {
   const { site, allConceptScheme } = useStaticQuery(graphql`
     query Colors {
       site {
+        buildTime
         siteMetadata {
           colors {
             skoHubWhite
@@ -85,6 +89,8 @@ export const getConfigAndConceptSchemes = () => {
           searchableAttributes
           customDomain
           failOnValidation
+          gitCommit
+          repositoryUrl
         }
       }
       allConceptScheme {
@@ -104,5 +110,9 @@ export const getConfigAndConceptSchemes = () => {
       [node.id]: { languages: node.fields.languages },
     }))
     .reduce((prev, curr) => ({ ...prev, ...curr }), {})
-  return { config: site.siteMetadata, conceptSchemes }
+  return {
+    config: site.siteMetadata,
+    buildTime: site.buildTime,
+    conceptSchemes,
+  }
 }

src/resolveGitCommit.js

@@ -0,0 +1,16 @@
+const { execSync: defaultExecSync } = require("child_process")
+
+function resolveGitCommit({ execSync = defaultExecSync } = {}) {
+  if (process.env.GITHUB_SHA) return process.env.GITHUB_SHA
+  if (process.env.CI_COMMIT_SHA) return process.env.CI_COMMIT_SHA
+  try {
+    return execSync("git rev-parse HEAD", {
+      encoding: "utf8",
+      stdio: ["ignore", "pipe", "ignore"],
+    }).trim()
+  } catch {
+    return null
+  }
+}
+
+module.exports = { resolveGitCommit }

test/buildInfo.test.js

@@ -0,0 +1,113 @@
+import { afterEach, beforeEach, describe, it, expect, vi } from "vitest"
+import { commitUrl, formatBuildTime, shortSha } from "../src/buildInfo"
+import { resolveGitCommit } from "../src/resolveGitCommit"
+
+describe("formatBuildTime", () => {
+  it("formats an ISO timestamp as 'YYYY-MM-DD HH:mm UTC'", () => {
+    expect(formatBuildTime("2026-04-30T14:30:42.123Z")).toBe(
+      "2026-04-30 14:30 UTC"
+    )
+  })
+
+  it("drops seconds and fractional seconds", () => {
+    expect(formatBuildTime("2026-01-01T00:00:59.999Z")).toBe(
+      "2026-01-01 00:00 UTC"
+    )
+  })
+
+  it("returns empty string for falsy input", () => {
+    expect(formatBuildTime("")).toBe("")
+    expect(formatBuildTime(null)).toBe("")
+    expect(formatBuildTime(undefined)).toBe("")
+  })
+})
+
+describe("shortSha", () => {
+  it("truncates a full git SHA to 7 chars", () => {
+    expect(shortSha("a1b2c3d4e5f67890abcdef1234567890abcdef12")).toBe("a1b2c3d")
+  })
+
+  it("returns the input unchanged when shorter than 7 chars", () => {
+    expect(shortSha("abc")).toBe("abc")
+  })
+
+  it("returns empty string for falsy input", () => {
+    expect(shortSha("")).toBe("")
+    expect(shortSha(null)).toBe("")
+    expect(shortSha(undefined)).toBe("")
+  })
+})
+
+describe("commitUrl", () => {
+  it("joins repo URL and SHA with /commit/", () => {
+    expect(
+      commitUrl("https://github.com/skohub-io/skohub-vocabs", "a1b2c3d")
+    ).toBe("https://github.com/skohub-io/skohub-vocabs/commit/a1b2c3d")
+  })
+
+  it("strips a single trailing slash from the repo URL", () => {
+    expect(
+      commitUrl("https://github.com/skohub-io/skohub-vocabs/", "a1b2c3d")
+    ).toBe("https://github.com/skohub-io/skohub-vocabs/commit/a1b2c3d")
+  })
+
+  it("returns empty string when either input is missing", () => {
+    expect(commitUrl("", "a1b2c3d")).toBe("")
+    expect(commitUrl("https://example.com/r", "")).toBe("")
+    expect(commitUrl(null, null)).toBe("")
+  })
+})
+
+describe("resolveGitCommit", () => {
+  const ORIGINAL_ENV = process.env
+  let execSync
+
+  beforeEach(() => {
+    process.env = { ...ORIGINAL_ENV }
+    delete process.env.GITHUB_SHA
+    delete process.env.CI_COMMIT_SHA
+    execSync = vi.fn()
+  })
+
+  afterEach(() => {
+    process.env = ORIGINAL_ENV
+  })
+
+  it("returns GITHUB_SHA when set", () => {
+    process.env.GITHUB_SHA = "github1111111111111111111111111111111111"
+    expect(resolveGitCommit({ execSync })).toBe(
+      "github1111111111111111111111111111111111"
+    )
+    expect(execSync).not.toHaveBeenCalled()
+  })
+
+  it("returns CI_COMMIT_SHA when GITHUB_SHA is absent", () => {
+    process.env.CI_COMMIT_SHA = "gitlab2222222222222222222222222222222222"
+    expect(resolveGitCommit({ execSync })).toBe(
+      "gitlab2222222222222222222222222222222222"
+    )
+    expect(execSync).not.toHaveBeenCalled()
+  })
+
+  it("prefers GITHUB_SHA over CI_COMMIT_SHA", () => {
+    process.env.GITHUB_SHA = "gh"
+    process.env.CI_COMMIT_SHA = "gl"
+    expect(resolveGitCommit({ execSync })).toBe("gh")
+  })
+
+  it("falls back to `git rev-parse HEAD` when no env var is set", () => {
+    execSync.mockReturnValue("local333333333\n")
+    expect(resolveGitCommit({ execSync })).toBe("local333333333")
+    expect(execSync).toHaveBeenCalledWith("git rev-parse HEAD", {
+      encoding: "utf8",
+      stdio: ["ignore", "pipe", "ignore"],
+    })
+  })
+
+  it("returns null when env vars are missing and git fails", () => {
+    execSync.mockImplementation(() => {
+      throw new Error("not a git repository")
+    })
+    expect(resolveGitCommit({ execSync })).toBeNull()
+  })
+})

test/footer.test.jsx

@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it, vi } from "vitest"
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest"
 import { render, screen } from "@testing-library/react"
 import React from "react"
 import Footer from "../src/components/footer"
@@ -7,14 +7,102 @@ import { mockConfig } from "./mocks/mockConfig"
 
 const useStaticQuery = vi.spyOn(Gatsby, `useStaticQuery`)
 
+const withMock = (overrides = {}) => ({
+  ...mockConfig,
+  site: {
+    ...mockConfig.site,
+    ...(overrides.site || {}),
+    siteMetadata: {
+      ...mockConfig.site.siteMetadata,
+      ...((overrides.site && overrides.site.siteMetadata) || {}),
+    },
+  },
+})
+
 describe("Footer", () => {
   beforeEach(() => {
-    useStaticQuery.mockImplementation(() => mockConfig)
+    delete process.env.GATSBY_RESPOSITORY_URL
+  })
+
+  afterEach(() => {
+    delete process.env.GATSBY_RESPOSITORY_URL
   })
 
-  it("renders footer", () => {
-    process.env.GATSBY_RESPOSITORY_URL = "http://test.com"
-    render(<Footer></Footer>)
+  it("renders Source link when repositoryUrl is set", () => {
+    useStaticQuery.mockImplementation(() =>
+      withMock({
+        site: {
+          siteMetadata: {
+            repositoryUrl: "https://github.com/skohub-io/skohub-vocabs",
+          },
+        },
+      })
+    )
+    render(<Footer />)
     expect(screen.getByRole("link", { name: "Source" })).toBeInTheDocument()
   })
+
+  it("renders timestamp only when no commit info is available", () => {
+    useStaticQuery.mockImplementation(() =>
+      withMock({
+        site: {
+          buildTime: "2026-04-30T14:30:42.000Z",
+          siteMetadata: { gitCommit: "", repositoryUrl: "" },
+        },
+      })
+    )
+    render(<Footer />)
+    expect(
+      screen.getByText("Last built: 2026-04-30 14:30 UTC")
+    ).toBeInTheDocument()
+    expect(
+      screen.queryByRole("link", { name: /a1b2c3d/ })
+    ).not.toBeInTheDocument()
+  })
+
+  it("renders timestamp + plain short SHA when no repositoryUrl", () => {
+    useStaticQuery.mockImplementation(() =>
+      withMock({
+        site: {
+          buildTime: "2026-04-30T14:30:42.000Z",
+          siteMetadata: {
+            gitCommit: "a1b2c3d4e5f67890abcdef1234567890abcdef12",
+            repositoryUrl: "",
+          },
+        },
+      })
+    )
+    render(<Footer />)
+    expect(
+      screen.getByText("Last built: 2026-04-30 14:30 UTC (a1b2c3d)")
+    ).toBeInTheDocument()
+  })
+
+  it("renders timestamp + linked short SHA when both are set", () => {
+    useStaticQuery.mockImplementation(() =>
+      withMock({
+        site: {
+          buildTime: "2026-04-30T14:30:42.000Z",
+          siteMetadata: {
+            gitCommit: "a1b2c3d4e5f67890abcdef1234567890abcdef12",
+            repositoryUrl: "https://github.com/skohub-io/skohub-vocabs",
+          },
+        },
+      })
+    )
+    render(<Footer />)
+    const link = screen.getByRole("link", { name: "a1b2c3d" })
+    expect(link).toHaveAttribute(
+      "href",
+      "https://github.com/skohub-io/skohub-vocabs/commit/a1b2c3d4e5f67890abcdef1234567890abcdef12"
+    )
+  })
+
+  it("does not render the Last built line when buildTime is missing", () => {
+    useStaticQuery.mockImplementation(() =>
+      withMock({ site: { buildTime: null } })
+    )
+    render(<Footer />)
+    expect(screen.queryByText(/Last built:/)).not.toBeInTheDocument()
+  })
 })

test/mocks/mockConfig.js

@@ -1,8 +1,11 @@
 export const mockConfig = {
   site: {
+    buildTime: "2026-04-30T14:30:00.000Z",
     siteMetadata: {
       searchableAttributes: ["prefLabel"],
       customDomain: "",
+      gitCommit: "",
+      repositoryUrl: "",
       colors: {
         skoHubWhite: "rgb(255, 255, 255)",
         skoHubDarkColor: "rgb(15, 85, 75)",