Merge pull request #321 from basecamp/more-robust-image-pruning

lib/mrsk/cli/prune.rb

@@ -12,7 +12,8 @@ class Mrsk::Cli::Prune < Mrsk::Cli::Base
     with_lock do
       on(MRSK.hosts) do
         execute *MRSK.auditor.record("Pruned images"), verbosity: :debug
-        execute *MRSK.prune.images
+        execute *MRSK.prune.dangling_images
+        execute *MRSK.prune.tagged_images
       end
     end
   end

lib/mrsk/commands/prune.rb

@@ -2,11 +2,15 @@ require "active_support/duration"
 require "active_support/core_ext/numeric/time"
 
 class Mrsk::Commands::Prune < Mrsk::Commands::Base
-  def images
+  def dangling_images
+    docker :image, :prune, "--force", "--filter", "label=service=#{config.service}", "--filter", "dangling=true"
+  end
+
+  def tagged_images
     pipe \
-      docker(:image, :ls, *service_filter, "--format", "'{{.Repository}}:{{.Tag}}'"),
+      docker(:image, :ls, *service_filter, "--format", "'{{.ID}} {{.Repository}}:{{.Tag}}'"),
       "grep -v -w \"#{active_image_list}\"",
-      "while read tag; do docker rmi $tag; done"
+      "while read image tag; do docker rmi $tag; done"
   end
 
   def containers(keep_last: 5)
@@ -22,7 +26,10 @@ class Mrsk::Commands::Prune < Mrsk::Commands::Base
     end
 
     def active_image_list
-      "$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=#{config.service} | tr -d '\\n')#{config.latest_image}"
+      # Pull the images that are used by any containers
+      # Append repo:latest - to avoid deleting the latest tag
+      # Append repo:<none> - to avoid deleting dangling images that are in use. Unused dangling images are deleted separately
+      "$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=#{config.service} | tr -d '\\n')#{config.latest_image}\\|#{config.repository}:<none>"
     end
 
     def service_filter

test/cli/prune_test.rb

@@ -10,7 +10,8 @@ class CliPruneTest < CliTestCase
 
   test "images" do
     run_command("images").tap do |output|
-      assert_match "docker image ls --filter label=service=app --format '{{.Repository}}:{{.Tag}}' | grep -v -w \"$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=app | tr -d '\\n')dhh/app:latest\" | while read tag; do docker rmi $tag; done on 1.1.1.", output
+      assert_match "docker image prune --force --filter label=service=app --filter dangling=true on 1.1.1.", output
+      assert_match "docker image ls --filter label=service=app --format '{{.ID}} {{.Repository}}:{{.Tag}}' | grep -v -w \"$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=app | tr -d '\\n')dhh/app:latest\\|dhh/app:<none>\" | while read image tag; do docker rmi $tag; done on 1.1.1.", output
     end
   end
 

test/commands/prune_test.rb

@@ -8,10 +8,16 @@ class CommandsPruneTest < ActiveSupport::TestCase
     }
   end
 
-  test "images" do
+  test "dangling images" do
     assert_equal \
-      "docker image ls --filter label=service=app --format '{{.Repository}}:{{.Tag}}' | grep -v -w \"$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=app | tr -d '\\n')dhh/app:latest\" | while read tag; do docker rmi $tag; done",
+      "docker image prune --force --filter label=service=app --filter dangling=true",
-      new_command.images.join(" ")
+      new_command.dangling_images.join(" ")
+  end
+
+  test "tagged images" do
+    assert_equal \
+      "docker image ls --filter label=service=app --format '{{.ID}} {{.Repository}}:{{.Tag}}' | grep -v -w \"$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=app | tr -d '\\n')dhh/app:latest\\|dhh/app:<none>\" | while read image tag; do docker rmi $tag; done",
+      new_command.tagged_images.join(" ")
   end
 
   test "containers" do