dockerTools: add finalImageName parameter for pullImage

pkgs/build-support/docker/default.nix

@@ -45,13 +45,18 @@ rec {
     , sha256
     , os ? "linux"
     , arch ? "amd64"
+
+      # This is used to set name to the pulled image
+    , finalImageName ? imageName
       # This used to set a tag to the pulled image
     , finalImageTag ? "latest"
-    , name ? fixName "docker-image-${imageName}-${finalImageTag}.tar"
+
+    , name ? fixName "docker-image-${finalImageName}-${finalImageTag}.tar"
     }:
 
     runCommand name {
-      inherit imageName imageDigest;
+      inherit imageDigest;
+      imageName = finalImageName;
       imageTag = finalImageTag;
       impureEnvVars = pkgs.stdenv.lib.fetchers.proxyImpureEnvVars;
       outputHashMode = "flat";
@@ -62,7 +67,7 @@ rec {
       SSL_CERT_FILE = "${pkgs.cacert.out}/etc/ssl/certs/ca-bundle.crt";
 
       sourceURL = "docker://${imageName}@${imageDigest}";
-      destNameTag = "${imageName}:${finalImageTag}";
+      destNameTag = "${finalImageName}:${finalImageTag}";
     } ''
       skopeo --override-os ${os} --override-arch ${arch} copy "$sourceURL" "docker-archive://$out:$destNameTag"
     '';

pkgs/build-support/docker/examples.nix

@@ -88,8 +88,9 @@ rec {
   nixFromDockerHub = pullImage {
     imageName = "nixos/nix";
     imageDigest = "sha256:85299d86263a3059cf19f419f9d286cc9f06d3c13146a8ebbb21b3437f598357";
-    sha256 = "0vnp3mhpk4ny3xa3cgngqsargnmvfgld54d5sn4b5av6yqzzp67z";
+    sha256 = "07q9y9r7fsd18sy95ybrvclpkhlal12d30ybnf089hq7v1hgxbi7";
     finalImageTag = "2.2.1";
+    finalImageName = "nix";
   };
 
   # 5. example of multiple contents, emacs and vi happily coexisting