Add container information to .containerenv

We have been asked to leak some container information and image information into the container to be used by certain tools. (Toolbox and others) Signed-off-by: Daniel J Walsh <[email protected]>
containers · Nov 24, 2020 · d9a7f13 · d9a7f13
1 parent af10f8c
commit d9a7f13
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Showing 2 changed files with 33 additions and 4 deletions.
diff --git a/run_linux.go b/run_linux.go
@@ -216,16 +216,28 @@ func (b *Builder) Run(command []string, options RunOptions) error {
 	}
 	// Empty file, so no need to recreate if it exists
 	if _, ok := bindFiles["/run/.containerenv"]; !ok {
-		// Empty string for now, but we may consider populating this later
 		containerenvPath := filepath.Join(path, "/run/.containerenv")
 		if err = os.MkdirAll(filepath.Dir(containerenvPath), 0755); err != nil {
 			return err
 		}
-		emptyFile, err := os.Create(containerenvPath)
-		if err != nil {
+
+		rootless := 0
+		if unshare.IsRootless() {
+			rootless = 1
+		}
+		// Populate the .containerenv with container information
+		containerenv := fmt.Sprintf(`\
+engine="buildah-%s"
+name=%q
+id=%q
+image=%q
+imageid=%q
+rootless=%d
+`, Version, b.Container, b.ContainerID, b.FromImage, b.FromImageID, rootless)
+
+		if err = ioutils.AtomicWriteFile(containerenvPath, []byte(containerenv), 0755); err != nil {
 			return err
 		}
-		emptyFile.Close()
 		if err := label.Relabel(containerenvPath, b.MountLabel, false); err != nil {
 			return err
 		}

diff --git a/tests/run.bats b/tests/run.bats
@@ -391,6 +391,23 @@ function configure_and_check_user() {
 	# test a standard mount to /run/.containerenv
 	run_buildah run $cid ls -1 /run/.containerenv
 	expect_output --substring "/run/.containerenv"
+
+	run_buildah run $cid sh -c '. /run/.containerenv; echo $engine'
+	expect_output --substring "buildah"
+
+	run_buildah run $cid sh -c '. /run/.containerenv; echo $name'
+	expect_output "alpine-working-container"
+
+	run_buildah run $cid sh -c '. /run/.containerenv; echo $image'
+	expect_output --substring "alpine:latest"
+
+	rootless=0
+	if ["$(id -u)" -ne 0 ]; then
+		rootless=1
+	fi
+
+	run_buildah run $cid sh -c '. /run/.containerenv; echo $rootless'
+	expect_output ${rootless}
 }
 
 @test "run-device" {