Show app version from git tag instead of dev commit-diff link

Dockerfile

@@ -73,6 +73,13 @@ RUN rm -rf node_modules
 # ---------- Runtime stage ----------
 FROM base
 
+# Application version for display in the UI (admin sidebar + site footers).
+# Computed on the host from `git describe --tags --always` and passed in by
+# the deploy tooling (see config/deploy.yml `builder.args`). The `.git` dir is
+# excluded from the build context (.dockerignore), so it cannot be derived here.
+ARG APP_VERSION
+ENV APP_VERSION=$APP_VERSION
+
 # Copy built artifacts
 COPY --from=build "${BUNDLE_PATH}" "${BUNDLE_PATH}"
 COPY --from=build /rails /rails

app/components/directory/footer.rb

@@ -62,9 +62,8 @@ def render_impressum
         data_nosnippet: true) do
       span { "#{t('colophon.year', year: Time.zone.today.year)} #{t('colophon.copyright')}" }
       span do
-        build = ENV['GIT_REV'] ? ENV['GIT_REV'][0, 7] : 'main'
         plain 'Build: '
-        link_to(build, "https://github.com/geeksforsocialchange/PlaceCal/commit/#{build}",
+        link_to(AppVersion.label(fallback: 'main'), AppVersion.url,
                 class: 'text-tertiary underline hover:decoration-primary')
       end
     end

app/components/footer.rb

@@ -128,10 +128,9 @@ def render_impressum
         plain t('colophon.address')
       end
       p do
-        build = ENV['GIT_REV'] ? ENV['GIT_REV'][0, 7] : 'main'
         plain 'Build: '
         tag.tt do
-          link_to(build, "https://github.com/geeksforsocialchange/PlaceCal/commit/#{build}")
+          link_to(AppVersion.label(fallback: 'main'), AppVersion.url)
         end
       end
     end

app/lib/app_version.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+# Derives a human-friendly application version for display in the UI.
+#
+# The version is injected at Docker build time via the +APP_VERSION+ env var
+# (see Dockerfile / config/deploy.yml), where it is set from
+# `git describe --tags --always` (e.g. "v0.27.3" on a tagged release, or
+# "v0.27.3-115-gabc1234" when ahead of the latest tag).
+#
+# Fallback chain for the displayed label:
+#   1. ENV['APP_VERSION']        — the git-describe version
+#   2. ENV['GIT_REV'][0, 7]      — short commit SHA (legacy)
+#   3. the supplied fallback     — 'dev' (admin) or 'main' (public footers)
+class AppVersion
+  REPO_URL = 'https://github.com/geeksforsocialchange/PlaceCal'
+
+  # @param fallback [String] label to use when no version/commit is available
+  # @return [String] the version label to display
+  def self.label(fallback: 'dev')
+    app_version || git_rev_short || fallback
+  end
+
+  # @return [String] a GitHub URL appropriate for the current version:
+  #   - the release-tag page when APP_VERSION is set
+  #   - the commit diff when only GIT_REV is available
+  #   - the repository home otherwise
+  def self.url
+    if (version = app_version)
+      "#{REPO_URL}/releases/tag/#{tag_for(version)}"
+    elsif (rev = git_rev)
+      "#{REPO_URL}/commit/#{rev}"
+    else
+      REPO_URL
+    end
+  end
+
+  def self.app_version
+    value = ENV.fetch('APP_VERSION', nil)
+    value.presence
+  end
+
+  def self.git_rev
+    value = ENV.fetch('GIT_REV', nil)
+    value.presence
+  end
+
+  def self.git_rev_short
+    git_rev&.slice(0, 7)
+  end
+
+  # Extract the leading tag from a `git describe` string so the release link
+  # stays valid even when the build is ahead of the latest tag.
+  # "v0.27.3-115-gabc1234" => "v0.27.3"; "v0.27.3" => "v0.27.3"
+  def self.tag_for(version)
+    version.sub(/-\d+-g[0-9a-f]+\z/, '')
+  end
+
+  private_class_method :app_version, :git_rev, :git_rev_short, :tag_for
+end

app/views/layouts/admin/application.rb

@@ -174,10 +174,9 @@ def leftbar_build_info
       icon(:code, size: '3')
       plain "#{t('admin.leftbar.build')}: "
       code(class: 'font-mono') do
-        git_rev = ENV.fetch('GIT_REV', nil)
         link_to(
-          git_rev ? git_rev[0, 7] : 'dev',
-          "https://github.com/geeksforsocialchange/PlaceCal/commit/#{git_rev}",
+          AppVersion.label(fallback: 'dev'),
+          AppVersion.url,
           class: 'text-placecal-teal-dark underline hover:no-underline'
         )
       end

config/deploy.yml

@@ -81,5 +81,10 @@ builder:
   arch: amd64
   args:
     RUBY_VERSION: <%= File.read('.ruby-version').strip %>
+    # Friendly version from the latest git tag (e.g. v0.27.3), computed on the
+    # host because the .git dir is excluded from the Docker build context.
+    # Baked into the image as ENV APP_VERSION by the Dockerfile, so it reaches
+    # runtime without a separate env var. Falls back to the short commit SHA.
+    APP_VERSION: <%= `git describe --tags --always 2>/dev/null`.strip %>
 
 # Database migrations run via bin/docker-entrypoint (db:prepare)

spec/components/admin/leftbar_build_info_spec.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+# Covers the build-info widget in the admin sidebar
+# (Views::Layouts::Admin::Application#leftbar_build_info). The surrounding
+# layout needs an authenticated controller, so we exercise just the build-info
+# fragment via a thin Phlex subclass.
+RSpec.describe Views::Layouts::Admin::Application, type: :component do
+  # Renders only the build-info fragment (a private method on the layout).
+  let(:build_info_component) do
+    Class.new(described_class) do
+      def view_template
+        leftbar_build_info
+      end
+    end
+  end
+
+  context "when APP_VERSION is set" do
+    before do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.9.1"))
+    end
+
+    it "shows the version label linking to the release tag" do
+      render_inline(build_info_component.new)
+
+      link = page.find("a", text: "v0.9.1")
+      expect(link[:href])
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/releases/tag/v0.9.1")
+    end
+
+    it "keeps the Build label" do
+      render_inline(build_info_component.new)
+
+      expect(page).to have_text(I18n.t("admin.leftbar.build"))
+    end
+  end
+
+  context "when neither APP_VERSION nor GIT_REV is set" do
+    before do
+      env = ENV.to_hash
+      env.delete("APP_VERSION")
+      env.delete("GIT_REV")
+      stub_const("ENV", env)
+    end
+
+    it "falls back to a 'dev' build label linking to the repo" do
+      render_inline(build_info_component.new)
+
+      link = page.find("a", text: "dev")
+      expect(link[:href]).to eq("https://github.com/geeksforsocialchange/PlaceCal")
+    end
+  end
+end

spec/components/directory/footer_component_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Components::Directory::Footer, type: :component do
+  context "when APP_VERSION is set" do
+    before do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.9.1"))
+    end
+
+    it "shows the version label linking to the release tag" do
+      render_inline(described_class.new)
+
+      link = page.find("a", text: "v0.9.1")
+      expect(link[:href])
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/releases/tag/v0.9.1")
+    end
+  end
+
+  context "when neither APP_VERSION nor GIT_REV is set" do
+    before do
+      env = ENV.to_hash
+      env.delete("APP_VERSION")
+      env.delete("GIT_REV")
+      stub_const("ENV", env)
+    end
+
+    it "falls back to a 'main' build label linking to the repo" do
+      render_inline(described_class.new)
+
+      link = page.find("a", text: "main")
+      expect(link[:href]).to eq("https://github.com/geeksforsocialchange/PlaceCal")
+    end
+  end
+end

spec/components/footer_component_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Components::Footer, type: :component do
+  context "when APP_VERSION is set" do
+    before do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.9.1"))
+    end
+
+    it "shows the version label linking to the release tag" do
+      render_inline(described_class.new(nil))
+
+      link = page.find("a", text: "v0.9.1")
+      expect(link[:href])
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/releases/tag/v0.9.1")
+    end
+  end
+
+  context "when neither APP_VERSION nor GIT_REV is set" do
+    before do
+      env = ENV.to_hash
+      env.delete("APP_VERSION")
+      env.delete("GIT_REV")
+      stub_const("ENV", env)
+    end
+
+    it "falls back to a 'main' build label linking to the repo" do
+      render_inline(described_class.new(nil))
+
+      link = page.find("a", text: "main")
+      expect(link[:href]).to eq("https://github.com/geeksforsocialchange/PlaceCal")
+    end
+  end
+end

spec/lib/app_version_spec.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe AppVersion do
+  describe ".label" do
+    it "returns APP_VERSION when set" do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.27.3", "GIT_REV" => "abcdef1234567"))
+      expect(described_class.label).to eq("v0.27.3")
+    end
+
+    it "falls back to the short GIT_REV when APP_VERSION is unset" do
+      env = ENV.to_hash.merge("GIT_REV" => "abcdef1234567")
+      env.delete("APP_VERSION")
+      stub_const("ENV", env)
+      expect(described_class.label).to eq("abcdef1")
+    end
+
+    it "falls back to the given fallback when neither is set" do
+      env = ENV.to_hash
+      env.delete("APP_VERSION")
+      env.delete("GIT_REV")
+      stub_const("ENV", env)
+      expect(described_class.label(fallback: "dev")).to eq("dev")
+      expect(described_class.label(fallback: "main")).to eq("main")
+    end
+
+    it "treats a blank APP_VERSION as unset" do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "", "GIT_REV" => "abcdef1234567"))
+      expect(described_class.label).to eq("abcdef1")
+    end
+  end
+
+  describe ".url" do
+    it "links to the release tag page when APP_VERSION is an exact tag" do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.27.3"))
+      expect(described_class.url)
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/releases/tag/v0.27.3")
+    end
+
+    it "strips the git-describe suffix when building the release tag link" do
+      stub_const("ENV", ENV.to_hash.merge("APP_VERSION" => "v0.27.3-115-g0b8e07e8"))
+      expect(described_class.url)
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/releases/tag/v0.27.3")
+    end
+
+    it "links to the commit diff when only GIT_REV is set" do
+      env = ENV.to_hash.merge("GIT_REV" => "abcdef1234567")
+      env.delete("APP_VERSION")
+      stub_const("ENV", env)
+      expect(described_class.url)
+        .to eq("https://github.com/geeksforsocialchange/PlaceCal/commit/abcdef1234567")
+    end
+
+    it "links to the repository home when nothing is set" do
+      env = ENV.to_hash
+      env.delete("APP_VERSION")
+      env.delete("GIT_REV")
+      stub_const("ENV", env)
+      expect(described_class.url).to eq("https://github.com/geeksforsocialchange/PlaceCal")
+    end
+  end
+end