Set env variables when running kamal app exec

Allow additional env variable to be set when running `kamal app exec`.
Works for both new and existing containers.

lib/kamal/cli/app.rb

@@ -70,13 +70,15 @@ class Kamal::Cli::App < Kamal::Cli::Base
   desc "exec [CMD]", "Execute a custom command on servers (use --help to show options)"
   option :interactive, aliases: "-i", type: :boolean, default: false, desc: "Execute command over ssh for an interactive shell (use for console/bash)"
   option :reuse, type: :boolean, default: false, desc: "Reuse currently running container instead of starting a new one"
+  option :env, aliases: "-e", type: :hash, desc: "Set environment variables for the command"
   def exec(cmd)
+    env = options[:env]
     case
     when options[:interactive] && options[:reuse]
       say "Get current version of running container...", :magenta unless options[:version]
       using_version(options[:version] || current_running_version) do |version|
         say "Launching interactive command with version #{version} via SSH from existing container on #{KAMAL.primary_host}...", :magenta
-        run_locally { exec KAMAL.app(role: KAMAL.primary_role).execute_in_existing_container_over_ssh(cmd, host: KAMAL.primary_host) }
+        run_locally { exec KAMAL.app(role: KAMAL.primary_role).execute_in_existing_container_over_ssh(cmd, host: KAMAL.primary_host, env: env) }
       end
 
     when options[:interactive]
@@ -84,7 +86,7 @@ class Kamal::Cli::App < Kamal::Cli::Base
       using_version(version_or_latest) do |version|
         say "Launching interactive command with version #{version} via SSH from new container on #{KAMAL.primary_host}...", :magenta
         run_locally do
-          exec KAMAL.app(role: KAMAL.primary_role).execute_in_new_container_over_ssh(cmd, host: KAMAL.primary_host)
+          exec KAMAL.app(role: KAMAL.primary_role).execute_in_new_container_over_ssh(cmd, host: KAMAL.primary_host, env: env)
         end
       end
 
@@ -98,7 +100,7 @@ class Kamal::Cli::App < Kamal::Cli::Base
 
           roles.each do |role|
             execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on app version #{version}", role: role), verbosity: :debug
-            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_existing_container(cmd))
+            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_existing_container(cmd, env: env))
           end
         end
       end
@@ -112,7 +114,7 @@ class Kamal::Cli::App < Kamal::Cli::Base
 
           roles.each do |role|
             execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on app version #{version}"), verbosity: :debug
-            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_new_container(cmd))
+            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_new_container(cmd, env: env))
           end
         end
       end

lib/kamal/commands/app/execution.rb

@@ -1,27 +1,29 @@
 module Kamal::Commands::App::Execution
-  def execute_in_existing_container(*command, interactive: false)
+  def execute_in_existing_container(*command, interactive: false, env:)
     docker :exec,
       ("-it" if interactive),
+      *argumentize("--env", env),
       container_name,
       *command
   end
 
-  def execute_in_new_container(*command, interactive: false)
+  def execute_in_new_container(*command, interactive: false, env:)
     docker :run,
       ("-it" if interactive),
       "--rm",
       *role&.env_args,
+      *argumentize("--env", env),
       *config.volume_args,
       *role&.option_args,
       config.absolute_image,
       *command
   end
 
-  def execute_in_existing_container_over_ssh(*command, host:)
-    run_over_ssh execute_in_existing_container(*command, interactive: true), host: host
+  def execute_in_existing_container_over_ssh(*command, host:, env:)
+    run_over_ssh execute_in_existing_container(*command, interactive: true, env: env), host: host
   end
 
-  def execute_in_new_container_over_ssh(*command, host:)
-    run_over_ssh execute_in_new_container(*command, interactive: true), host: host
+  def execute_in_new_container_over_ssh(*command, host:, env:)
+    run_over_ssh execute_in_new_container(*command, interactive: true, env: env), host: host
   end
 end

test/commands/app_test.rb

@@ -174,36 +174,48 @@ class CommandsAppTest < ActiveSupport::TestCase
   test "execute in new container" do
     assert_equal \
       "docker run --rm --env-file .kamal/env/roles/app-web.env dhh/app:999 bin/rails db:setup",
-      new_command.execute_in_new_container("bin/rails", "db:setup").join(" ")
+      new_command.execute_in_new_container("bin/rails", "db:setup", env: {}).join(" ")
+  end
+
+  test "execute in new container with env" do
+    assert_equal \
+      "docker run --rm --env-file .kamal/env/roles/app-web.env --env foo=\"bar\" dhh/app:999 bin/rails db:setup",
+      new_command.execute_in_new_container("bin/rails", "db:setup", env: { "foo" => "bar" }).join(" ")
   end
 
   test "execute in new container with custom options" do
     @config[:servers] = { "web" => { "hosts" => [ "1.1.1.1" ], "options" => { "mount" => "somewhere", "cap-add" => true } } }
     assert_equal \
       "docker run --rm --env-file .kamal/env/roles/app-web.env --mount \"somewhere\" --cap-add dhh/app:999 bin/rails db:setup",
-      new_command.execute_in_new_container("bin/rails", "db:setup").join(" ")
+      new_command.execute_in_new_container("bin/rails", "db:setup", env: {}).join(" ")
   end
 
   test "execute in existing container" do
     assert_equal \
       "docker exec app-web-999 bin/rails db:setup",
-      new_command.execute_in_existing_container("bin/rails", "db:setup").join(" ")
+      new_command.execute_in_existing_container("bin/rails", "db:setup", env: {}).join(" ")
+  end
+
+  test "execute in existing container with env" do
+    assert_equal \
+      "docker exec --env foo=\"bar\" app-web-999 bin/rails db:setup",
+      new_command.execute_in_existing_container("bin/rails", "db:setup", env: { "foo" => "bar" }).join(" ")
   end
 
   test "execute in new container over ssh" do
     assert_match %r{docker run -it --rm --env-file .kamal/env/roles/app-web.env dhh/app:999 bin/rails c},
-      new_command.execute_in_new_container_over_ssh("bin/rails", "c", host: "app-1")
+      new_command.execute_in_new_container_over_ssh("bin/rails", "c", host: "app-1", env: {})
   end
 
   test "execute in new container with custom options over ssh" do
     @config[:servers] = { "web" => { "hosts" => [ "1.1.1.1" ], "options" => { "mount" => "somewhere", "cap-add" => true } } }
     assert_match %r{docker run -it --rm --env-file .kamal/env/roles/app-web.env --mount \"somewhere\" --cap-add dhh/app:999 bin/rails c},
-      new_command.execute_in_new_container_over_ssh("bin/rails", "c", host: "app-1")
+      new_command.execute_in_new_container_over_ssh("bin/rails", "c", host: "app-1", env: {})
   end
 
   test "execute in existing container over ssh" do
     assert_match %r{docker exec -it app-web-999 bin/rails c},
-      new_command.execute_in_existing_container_over_ssh("bin/rails", "c", host: "app-1")
+      new_command.execute_in_existing_container_over_ssh("bin/rails", "c", host: "app-1", env: {})
   end
 
   test "run over ssh" do