Add Podman check to #running_in_container?

This solves the issue of running Selenium tests on Arm Mac (via Podman
Desktop), among other issues.

Author: awilfox

lib/berkeley_library/docker.rb

@@ -7,7 +7,7 @@ module BerkeleyLibrary
   module Docker
     class << self
       def running_in_container?
-        File.exist?('/.dockerenv') || init_cgroup_is_dockerish?
+        File.exist?('/.dockerenv') || init_cgroup_is_dockerish? || env_is_podmanish?
       end
 
       private
@@ -19,6 +19,10 @@ def init_cgroup_is_dockerish?
           false
         end
       end
+
+      def env_is_podmanish?
+        ENV.fetch('container', '') == 'podman'
+      end
     end
   end
 end

spec/berkeley_library/docker_spec.rb

@@ -35,18 +35,21 @@ module BerkeleyLibrary
 
       it 'is true when /.dockerenv exists' do
         mock_dockerenv
+        mock_podman_env(false)
         expect(BerkeleyLibrary::Docker.running_in_container?).to be true
       end
 
       it 'is true when /proc/1/cgroup is docker-like' do
         mock_dockerenv(false)
         mock_init_cgroup
+        mock_podman_env(false)
         expect(BerkeleyLibrary::Docker.running_in_container?).to be true
       end
 
       it 'is false when /proc/1/cgroup is traditional' do
         mock_dockerenv(false)
         mock_init_cgroup(false)
+        mock_podman_env(false)
         expect(BerkeleyLibrary::Docker.running_in_container?).to be false
       end
 
@@ -55,6 +58,21 @@ module BerkeleyLibrary
         expect(File)
           .to receive(:open).with('/proc/1/cgroup')
           .and_raise(Errno::ENOENT)
+        mock_podman_env(false)
+        expect(BerkeleyLibrary::Docker.running_in_container?).to be false
+      end
+
+      it 'is true when container=podman is present in environment' do
+        mock_dockerenv(false)
+        mock_init_cgroup(false)
+        mock_podman_env(true)
+        expect(BerkeleyLibrary::Docker.running_in_container?).to be true
+      end
+
+      it 'is false when container=podman is not present in environment' do
+        mock_dockerenv(false)
+        mock_init_cgroup(false)
+        mock_podman_env(false)
         expect(BerkeleyLibrary::Docker.running_in_container?).to be false
       end
 
@@ -72,6 +90,12 @@ def mock_init_cgroup(dockerish = true)
           .and_return(
             StringIO.new(dockerish ? DOCKERISH_CGROUP : TRADITIONAL_CGROUP))
       end
+
+      def mock_podman_env(exists = true)
+        allow(ENV)
+          .to receive(:fetch).with('container', '')
+          .and_return(exists ? 'podman' : '')
+      end
     end
   end
 end