Configure fonts on both docker containers

Author: ibbem

Dockerfile

@@ -19,11 +19,15 @@ RUN nix-shell -p dos2unix --run 'find . -exec dos2unix {} +'
 # itselves) using the default nix binary cache.
 RUN nix-build
 
+# Build required fonts and their cache.
+RUN mkdir -p /etc/fonts && nix-build nix/fontconfig.nix --out-link /etc/fonts/fonts.conf
+RUN mkdir -p /var/cache/fontconfig && nix-shell -p fontconfig --run fc-cache
+
 # Copy DiffDetective with all runtime dependencies (ignoring build-time
 # dependencies) to a separate folder. Such a subset of the Nix store is called a
 # closure and enables us to create a minimal Docker container.
 RUN mkdir closure
-RUN nix-store -qR result | xargs cp -Rt closure
+RUN nix-store -qR result /etc/fonts/fonts.conf | xargs cp -Rt closure
 
 # Start building the final container.
 FROM scratch
@@ -40,5 +44,9 @@ COPY --from=builder /home/user/result /DiffDetective
 # Copy the necessary data. Beware that this directory might have impure files.
 COPY data /home/user/data
 
+# Install fonts
+COPY --from=builder /etc/fonts/fonts.conf /etc/fonts/fonts.conf
+COPY --from=builder /var/cache/fontconfig /var/cache/fontconfig
+
 ENV DISPLAY=:0 HOME=/home/user
 CMD ["/DiffDetective/bin/DiffDetective-Demo"]

nix/docker.nix

@@ -16,23 +16,12 @@ in {
 
     copyToRoot = pkgs.buildEnv {
       name = "DiffDetective-Demo-image-root";
-      paths = [ (DiffDetectiveDemo.src + "/data") ];
+      paths = [(DiffDetectiveDemo.src + "/data")];
       extraPrefix = config.WorkingDir + "/data";
     };
 
     runAsRoot = ''
-      mkdir -p /etc/fonts
-
-      cat >/etc/fonts/fonts.conf <<"EOF"
-      <?xml version="1.0" encoding="UTF-8"?>
-      <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
-      <fontconfig>
-        <description>Configuration file</description>
-        <dir>${pkgs.dejavu_fonts}/share/fonts</dir>
-        <cachedir>/var/cache/fontconfig</cachedir>
-      </fontconfig>
-      EOF
-
+      install -Dm644 ${import ./fontconfig.nix {inherit sources system pkgs;}} /etc/fonts/fonts.conf
       mkdir -p /var/cache/fontconfig
       ${pkgs.fontconfig}/bin/fc-cache
     '';

nix/fontconfig.nix

@@ -0,0 +1,22 @@
+{
+  sources ? import ./sources.nix,
+  system ? builtins.currentSystem,
+  pkgs ?
+    import sources.nixpkgs {
+      overlays = [];
+      config = {};
+      inherit system;
+    },
+}:
+pkgs.writeTextFile {
+  name = "fonts.conf";
+  text = ''
+    <?xml version="1.0" encoding="UTF-8"?>
+    <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
+    <fontconfig>
+      <description>Configuration file</description>
+      <dir>${pkgs.dejavu_fonts}/share/fonts</dir>
+      <cachedir>/var/cache/fontconfig</cachedir>
+    </fontconfig>
+  '';
+}