From 8c0459f6118a7021acad0d07eeece08c0d9bd87b Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Sat, 11 Jul 2020 15:51:58 +0200
Subject: [PATCH] dockerTools: Always set imageTag attribute

The image tag can be specified or generated from the output hash.
Previously, a generated tag could be recovered from the evaluated
image with some string operations.

However, with the introduction of streamLayeredImage, it's not
feasible to compute the generated tag yourself.

With this change, the imageTag attribute is set unconditionally,
for the buildImage, buildLayeredImage, streamLayeredImage functions.
---
 nixos/tests/docker-tools.nix           | 37 ++++++++++++++++++++++++++
 pkgs/build-support/docker/default.nix  | 12 +++++++++
 pkgs/build-support/docker/examples.nix | 18 +++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/nixos/tests/docker-tools.nix b/nixos/tests/docker-tools.nix
index 21512be201a..5ce67695de4 100644
--- a/nixos/tests/docker-tools.nix
+++ b/nixos/tests/docker-tools.nix
@@ -30,8 +30,45 @@ import ./make-test-python.nix ({ pkgs, ... }: {
         )
 
     docker.succeed("docker run --rm ${examples.bash.imageName} bash --version")
+    # Check imageTag attribute matches image
+    docker.succeed("docker images --format '{{.Tag}}' | grep -F '${examples.bash.imageTag}'")
     docker.succeed("docker rmi ${examples.bash.imageName}")
 
+    # The remaining combinations
+    with subtest("Ensure imageTag attribute matches image"):
+        docker.succeed(
+            "docker load --input='${examples.bashNoTag}'"
+        )
+        docker.succeed(
+            "docker images --format '{{.Tag}}' | grep -F '${examples.bashNoTag.imageTag}'"
+        )
+        docker.succeed("docker rmi ${examples.bashNoTag.imageName}:${examples.bashNoTag.imageTag}")
+
+        docker.succeed(
+            "docker load --input='${examples.bashNoTagLayered}'"
+        )
+        docker.succeed(
+            "docker images --format '{{.Tag}}' | grep -F '${examples.bashNoTagLayered.imageTag}'"
+        )
+        docker.succeed("docker rmi ${examples.bashNoTagLayered.imageName}:${examples.bashNoTagLayered.imageTag}")
+
+        docker.succeed(
+            "${examples.bashNoTagStreamLayered} | docker load"
+        )
+        docker.succeed(
+            "docker images --format '{{.Tag}}' | grep -F '${examples.bashNoTagStreamLayered.imageTag}'"
+        )
+        docker.succeed(
+            "docker rmi ${examples.bashNoTagStreamLayered.imageName}:${examples.bashNoTagStreamLayered.imageTag}"
+        )
+
+        docker.succeed(
+            "docker load --input='${examples.nixLayered}'"
+        )
+        docker.succeed("docker images --format '{{.Tag}}' | grep -F '${examples.nixLayered.imageTag}'")
+        docker.succeed("docker rmi ${examples.nixLayered.imageName}")
+
+
     with subtest(
         "Check if the nix store is correctly initialized by listing "
         "dependencies of the installed Nix binary"
diff --git a/pkgs/build-support/docker/default.nix b/pkgs/build-support/docker/default.nix
index 7ff325382a6..bf815af6f7c 100644
--- a/pkgs/build-support/docker/default.nix
+++ b/pkgs/build-support/docker/default.nix
@@ -442,6 +442,7 @@ rec {
     in
       runCommand "${name}.tar.gz" {
         inherit (stream) imageName;
+        passthru = { inherit (stream) imageTag; };
         buildInputs = [ pigz ];
       } "${stream} | pigz -nT > $out";
 
@@ -517,6 +518,11 @@ rec {
         layerClosure = writeReferencesToFile layer;
         passthru.buildArgs = args;
         passthru.layer = layer;
+        passthru.imageTag =
+          if tag != null
+            then lib.toLower tag
+            else
+              lib.head (lib.strings.splitString "-" (baseNameOf result.outPath));
         # Docker can't be made to run darwin binaries
         meta.badPlatforms = lib.platforms.darwin;
       } ''
@@ -737,6 +743,11 @@ rec {
       conf = runCommand "${name}-conf.json" {
         inherit maxLayers created;
         imageName = lib.toLower name;
+        passthru.imageTag =
+          if tag != null
+            then tag
+            else
+              lib.head (lib.strings.splitString "-" (baseNameOf conf.outPath));
         paths = referencesByPopularity overallClosure;
         buildInputs = [ jq ];
       } ''
@@ -792,6 +803,7 @@ rec {
       '';
       result = runCommand "stream-${name}" {
         inherit (conf) imageName;
+        passthru = { inherit (conf) imageTag; };
         buildInputs = [ makeWrapper ];
       } ''
         makeWrapper ${streamScript} $out --add-flags ${conf}
diff --git a/pkgs/build-support/docker/examples.nix b/pkgs/build-support/docker/examples.nix
index 81dae9b6124..0d907c2d64b 100644
--- a/pkgs/build-support/docker/examples.nix
+++ b/pkgs/build-support/docker/examples.nix
@@ -364,4 +364,22 @@ rec {
     created = "now";
   };
 
+  # buildImage without explicit tag
+  bashNoTag = pkgs.dockerTools.buildImage {
+    name = "bash-no-tag";
+    contents = pkgs.bashInteractive;
+  };
+
+  # buildLayeredImage without explicit tag
+  bashNoTagLayered = pkgs.dockerTools.buildLayeredImage {
+    name = "bash-no-tag-layered";
+    contents = pkgs.bashInteractive;
+  };
+
+  # buildImage without explicit tag
+  bashNoTagStreamLayered = pkgs.dockerTools.streamLayeredImage {
+    name = "bash-no-tag-stream-layered";
+    contents = pkgs.bashInteractive;
+  };
+
 }