support for detecting if inside docker container.

2 files changed, 137 insertions, 24 deletions

diff --git a/lib/ohai/plugins/linux/virtualization.rb b/lib/ohai/plugins/linux/virtualization.rb
index e76398fa..1990b773 100644
--- a/lib/ohai/plugins/linux/virtualization.rb
+++ b/lib/ohai/plugins/linux/virtualization.rb
@@ -27,6 +27,10 @@ Ohai.plugin(:Virtualization) do
     which('lxc-version')
   end
 
+  def docker_exists?
+    which('docker')
+  end
+
   collect_data(:linux) do
     virtualization Mash.new unless virtualization
     virtualization[:systems] = Mash.new unless virtualization[:systems]
@@ -174,9 +178,9 @@ Ohai.plugin(:Virtualization) do
     # Kernel docs, https://www.kernel.org/doc/Documentation/cgroups
     if File.exists?("/proc/self/cgroup")
       if File.read("/proc/self/cgroup") =~ %r{^\d+:[^:]+:/(lxc|docker)/.+$}
-        virtualization[:system] = "lxc"
+        virtualization[:system] = $1
         virtualization[:role] = "guest"
-        virtualization[:systems][:lxc] = "guest"
+        virtualization[:systems][$1.to_sym] = "guest"
       elsif lxc_version_exists? && File.read("/proc/self/cgroup") =~ %r{\d:[^:]+:/$}
         # lxc-version shouldn't be installed by default
         # Even so, it is likely we are on an LXC capable host that is not being used as such
@@ -185,12 +189,15 @@ Ohai.plugin(:Virtualization) do
           virtualization[:system] = "lxc"
           virtualization[:role] = "host"
         end
-
         # In general, the 'systems' framework from OHAI-182 is less susceptible to conflicts
         # But, this could overwrite virtualization[:systems][:lxc] = "guest"
         # If so, we may need to look further for a differentiator (OHAI-573)
         virtualization[:systems][:lxc] = "host"
       end
+    elsif File.exists?("/.dockerenv") || File.exists?("/.dockerinit")
+        virtualization[:system] = "docker"
+        virtualization[:role] = "guest"
+        virtualization[:systems][:docker] = "guest"
     end
   end
 end
diff --git a/spec/unit/plugins/linux/virtualization_spec.rb b/spec/unit/plugins/linux/virtualization_spec.rb
index 19a2a46f..a9e2ae10 100644
--- a/spec/unit/plugins/linux/virtualization_spec.rb
+++ b/spec/unit/plugins/linux/virtualization_spec.rb
@@ -33,6 +33,8 @@ describe Ohai::System, "Linux virtualization platform" do
     allow(File).to receive(:exists?).with("/proc/bc/0").and_return(false)
     allow(File).to receive(:exists?).with("/proc/vz").and_return(false)
     allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(false)
+    allow(File).to receive(:exists?).with("/.dockerenv").and_return(false)
+    allow(File).to receive(:exists?).with("/.dockerinit").and_return(false)
   end
 
   describe "when we are checking for xen" do
@@ -357,27 +359,6 @@ CGROUP
       expect(@plugin[:virtualization][:systems][:lxc]).to eq("guest")
     end
 
-    it "should set lxc guest if /proc/self/cgroup exist and there are /docker/<name> mounts" do
-      self_cgroup=<<-CGROUP
-11:hugetlb:/
-10:perf_event:/
-9:blkio:/
-8:net_cls:/
-7:freezer:/
-6:devices:/
-5:memory:/
-4:cpuacct,cpu:/docker/9c2adaa4c391ec0d3bf994fbd91ff30c3d317694d179e5b1dc7e1e4c8ed56b61
-3:cpuset:/
-2:name=systemd:/system.slice/docker.service
-CGROUP
-      expect(File).to receive(:exists?).with("/proc/self/cgroup").and_return(true)
-      allow(File).to receive(:read).with("/proc/self/cgroup").and_return(self_cgroup)
-      @plugin.run
-      expect(@plugin[:virtualization][:system]).to eq("lxc")
-      expect(@plugin[:virtualization][:role]).to eq("guest")
-      expect(@plugin[:virtualization][:systems][:lxc]).to eq("guest")
-    end
-
     it "should set not set anything if /proc/self/cgroup exist and the cgroup is named arbitrarily, it isn't necessarily lxc." do
       self_cgroup=<<-CGROUP
 8:blkio:/Charlie
@@ -446,6 +427,131 @@ CGROUP
     end
   end
 
+  describe "when we are checking for docker" do
+    it "should set docker guest if /proc/self/cgroup exist and there are /docker/<hexadecimal> mounts" do
+      self_cgroup=<<-CGROUP
+8:blkio:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+7:net_cls:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+6:freezer:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+5:devices:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+4:memory:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+3:cpuacct:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+2:cpu:/docker/baa660ed81bc81d262ac6e19486142aeec5fce2043e2a173eb2505c6fbed89bc
+1:cpuset:/
+CGROUP
+      allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(true)
+      allow(File).to receive(:read).with("/proc/self/cgroup").and_return(self_cgroup)
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).to eq("docker")
+      expect(@plugin[:virtualization][:role]).to eq("guest")
+      expect(@plugin[:virtualization][:systems][:docker]).to eq("guest")
+    end
+
+    it "should set docker guest if /proc/self/cgroup exist and there are /docker/<name> mounts" do
+      self_cgroup=<<-CGROUP
+8:blkio:/docker/vanilla
+7:net_cls:/docker/vanilla
+6:freezer:/docker/vanilla
+5:devices:/docker/vanilla
+4:memory:/docker/vanilla
+3:cpuacct:/docker/vanilla
+2:cpu:/docker/vanilla
+1:cpuset:/docker/vanilla
+CGROUP
+      allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(true)
+      allow(File).to receive(:read).with("/proc/self/cgroup").and_return(self_cgroup)
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).to eq("docker")
+      expect(@plugin[:virtualization][:role]).to eq("guest")
+      expect(@plugin[:virtualization][:systems][:docker]).to eq("guest")
+    end
+
+    it "should set not set anything if /proc/self/cgroup exist and the cgroup is named arbitrarily, it isn't necessarily lxc." do
+      self_cgroup=<<-CGROUP
+8:blkio:/Charlie
+7:net_cls:/Charlie
+6:freezer:/Charlie
+5:devices:/Charlie
+4:memory:/Charlie
+3:cpuacct:/Charlie
+2:cpu:/Charlie
+1:cpuset:/Charlie
+CGROUP
+      allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(true)
+      allow(File).to receive(:read).with("/proc/self/cgroup").and_return(self_cgroup)
+      @plugin.run
+      expect(@plugin[:virtualization]).to eq({'systems' => {}})
+    end
+
+    context "/proc/self/cgroup only has / mounts" do
+      before(:each) do
+        self_cgroup=<<-CGROUP
+8:blkio:/
+7:net_cls:/
+6:freezer:/
+5:devices:/
+4:memory:/
+3:cpuacct:/
+2:cpu:/
+1:cpuset:/
+CGROUP
+        allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(true)
+        allow(File).to receive(:read).with("/proc/self/cgroup").and_return(self_cgroup)
+        @plugin.run
+        expect(@plugin[:virtualization]).to eq({'systems' => {}})
+      end
+
+    end
+
+    it "does not set the old virtualization attributes if they are already set" do
+      allow(@plugin).to receive(:docker_exists?).and_return("/usr/bin/docker")
+      @plugin[:virtualization] = Mash.new
+      @plugin[:virtualization][:system] = "the cloud"
+      @plugin[:virtualization][:role] = "cumulonimbus"
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).not_to eq("docker")
+      expect(@plugin[:virtualization][:role]).not_to eq("host")
+    end
+
+    it "does not set docker host if docker does not exist" do
+      allow(@plugin).to receive(:docker_exists?).and_return(false)
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).to be_nil
+      expect(@plugin[:virtualization][:role]).to be_nil
+      expect(@plugin[:virtualization]).to eq({'systems' => {}})
+    end
+
+    it "should not set virtualization if /proc/self/cgroup isn't there" do
+      allow(File).to receive(:exists?).with("/proc/self/cgroup").and_return(false)
+      @plugin.run
+      expect(@plugin[:virtualization]).to eq({'systems' => {}})
+    end
+
+    it "should set virtualization if /.dockerenv exists" do
+      allow(File).to receive(:exists?).with("/.dockerenv").and_return(true)
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).to eq("docker")
+      expect(@plugin[:virtualization][:role]).to eq("guest")
+      expect(@plugin[:virtualization][:systems][:docker]).to eq("guest")
+    end
+
+    it "should set virtualization if /.dockerinit exists" do
+      allow(File).to receive(:exists?).with("/.dockerinit").and_return(true)
+      @plugin.run
+      expect(@plugin[:virtualization][:system]).to eq("docker")
+      expect(@plugin[:virtualization][:role]).to eq("guest")
+      expect(@plugin[:virtualization][:systems][:docker]).to eq("guest")
+    end
+
+    it "should not set virtualization if /.dockerenv or /.dockerinit doesn't exists" do
+      allow(File).to receive(:exists?).with("/.dockerenv").and_return(false)
+      allow(File).to receive(:exists?).with("/.dockerinit").and_return(false)
+      @plugin.run
+      expect(@plugin[:virtualization]).to eq({'systems' => {}})
+    end
+
+  end
+
   it "should not set virtualization if no tests match" do
     @plugin.run
     expect(@plugin[:virtualization]).to eq({'systems' => {}})