Avoid setting env via SSHKit

SSHKit puts the env in the command, so leaks them in process listings.

lib/kamal/cli/base.rb

@@ -135,8 +135,10 @@ module Kamal::Cli
           details = { hosts: KAMAL.hosts.join(","), command: command, subcommand: subcommand }
 
           say "Running the #{hook} hook...", :magenta
-          run_locally do
-            execute *KAMAL.hook.run(hook, **details, **extra_details)
+          with_env KAMAL.hook.env(**details, **extra_details) do
+            run_locally do
+              execute *KAMAL.hook.run(hook)
+            end
           rescue SSHKit::Command::Failed => e
             raise HookError.new("Hook `#{hook}` failed:\n#{e.message}")
           end
@@ -183,5 +185,14 @@ module Kamal::Cli
           execute(*KAMAL.server.ensure_run_directory)
         end
       end
+
+      def with_env(env)
+        current_env = ENV.to_h.dup
+        ENV.update(env)
+        yield
+      ensure
+        ENV.clear
+        ENV.update(current_env)
+      end
   end
 end

lib/kamal/cli/build.rb

@@ -30,28 +30,30 @@ class Kamal::Cli::Build < Kamal::Cli::Base
       say "Building with uncommitted changes:\n #{uncommitted_changes}", :yellow
     end
 
-    run_locally do
-      begin
-        execute *KAMAL.builder.inspect_builder
-      rescue SSHKit::Command::Failed => e
-        if e.message =~ /(context not found|no builder|no compatible builder|does not exist)/
-          warn "Missing compatible builder, so creating a new one first"
-          begin
-            cli.remove
-          rescue SSHKit::Command::Failed
-            raise unless e.message =~ /(context not found|no builder|does not exist)/
+    with_env(KAMAL.config.builder.secrets) do
+      run_locally do
+        begin
+          execute *KAMAL.builder.inspect_builder
+        rescue SSHKit::Command::Failed => e
+          if e.message =~ /(context not found|no builder|no compatible builder|does not exist)/
+            warn "Missing compatible builder, so creating a new one first"
+            begin
+              cli.remove
+            rescue SSHKit::Command::Failed
+              raise unless e.message =~ /(context not found|no builder|does not exist)/
+            end
+            cli.create
+          else
+            raise
           end
-          cli.create
-        else
-          raise
         end
-      end
 
-      # Get the command here to ensure the Dir.chdir doesn't interfere with it
-      push = KAMAL.builder.push
+        # Get the command here to ensure the Dir.chdir doesn't interfere with it
+        push = KAMAL.builder.push
 
-      KAMAL.with_verbosity(:debug) do
-        Dir.chdir(KAMAL.config.builder.build_directory) { execute *push, env: KAMAL.config.builder.secrets }
+        KAMAL.with_verbosity(:debug) do
+          Dir.chdir(KAMAL.config.builder.build_directory) { execute *push }
+        end
       end
     end
   end

lib/kamal/cli/main.rb

@@ -48,7 +48,7 @@ class Kamal::Cli::Main < Kamal::Cli::Base
       end
     end
 
-    run_hook "post-deploy", secrets: true, runtime: runtime.round
+    run_hook "post-deploy", secrets: true, runtime: runtime.round.to_s
   end
 
   desc "redeploy", "Deploy app to servers without bootstrapping servers, starting kamal-proxy, pruning, and registry login"
@@ -75,7 +75,7 @@ class Kamal::Cli::Main < Kamal::Cli::Base
       end
     end
 
-    run_hook "post-deploy", secrets: true, runtime: runtime.round
+    run_hook "post-deploy", secrets: true, runtime: runtime.round.to_s
   end
 
   desc "rollback [VERSION]", "Rollback app to VERSION"
@@ -99,7 +99,7 @@ class Kamal::Cli::Main < Kamal::Cli::Base
       end
     end
 
-    run_hook "post-deploy", secrets: true, runtime: runtime.round if rolled_back
+    run_hook "post-deploy", secrets: true, runtime: runtime.round.to_s if rolled_back
   end
 
   desc "details", "Show details about all containers"

lib/kamal/commands/hook.rb

@@ -1,9 +1,12 @@
 class Kamal::Commands::Hook < Kamal::Commands::Base
-  def run(hook, secrets: false, **details)
-    env = tags(**details).env
-    env.merge!(config.secrets.to_h) if secrets
+  def run(hook)
+    [ hook_file(hook) ]
+  end
 
-    [ hook_file(hook), env: env ]
+  def env(secrets: false, **details)
+    tags(**details).env.tap do |env|
+      env.merge!(config.secrets.to_h) if secrets
+    end
   end
 
   def hook_exists?(hook)