Buildah bud should not use stdin by default

Fixes: containers/podman#8066 Is reporting that buildah is eating stdin. I don't beleive we should be using stdin when doing a buildah bud command unless `buildah bud -` is specified. After this PR, the `-` Dockerfile is still handled. Signed-off-by: Daniel J Walsh <[email protected]>
rhatdan · Oct 20, 2020 · 319d9cc · 319d9cc
1 parent 9229549
commit 319d9cc
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Showing 2 changed files with 23 additions and 10 deletions.
diff --git a/cmd/buildah/bud.go b/cmd/buildah/bud.go
@@ -198,8 +198,7 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		return errors.Wrapf(err, "error evaluating symlinks in build context path")
 	}
 
-	var stdin, stdout, stderr, reporter *os.File
-	stdin = os.Stdin
+	var stdout, stderr, reporter *os.File
 	stdout = os.Stdout
 	stderr = os.Stderr
 	reporter = os.Stderr
@@ -302,13 +301,6 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		return errors.Wrapf(err, "unable to obtain decrypt config")
 	}
 
-	if iopts.Jobs > 1 {
-		stdin, err = os.OpenFile("/dev/null", os.O_RDONLY|os.O_CREATE, 0000)
-		if err != nil {
-			return err
-		}
-	}
-
 	options := imagebuildah.BuildOptions{
 		AddCapabilities:         iopts.CapAdd,
 		AdditionalTags:          tags,
@@ -329,7 +321,6 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		ForceRmIntermediateCtrs: iopts.ForceRm,
 		IDMappingOptions:        idmappingOptions,
 		IIDFile:                 iopts.Iidfile,
-		In:                      stdin,
 		Isolation:               isolation,
 		Labels:                  iopts.Label,
 		Layers:                  layers,

diff --git a/tests/bud.bats b/tests/bud.bats
@@ -2273,3 +2273,25 @@ EOM
   expect_output --substring "CapBnd:	00000000a80425fb"
   expect_output --substring "CapEff:	0000000000000000"
 }
+
+@test "bud does not gobble stdin" {
+  _prefetch alpine
+
+  ctxdir=${TESTDIR}/bud
+  mkdir -p $ctxdir
+  cat >$ctxdir/Dockerfile <<EOF
+FROM alpine
+RUN true
+EOF
+
+  random_msg=$(head -10 /dev/urandom | tr -dc a-zA-Z0-9 | head -c12)
+
+  # Prior to #2708, buildah bud would gobble up its stdin even if it
+  # didn't actually use it. This prevented the use of 'cmdlist | bash';
+  # if 'buildah bud' was in cmdlist, everything past it would be lost.
+  #
+  # This is ugly but effective: it checks that buildah passes stdin untouched.
+  passthru=$(echo "$random_msg" | (run_buildah bud --quiet --signature-policy ${TESTSDIR}/policy.json -t stdin-test ${ctxdir} >/dev/null; cat))
+
+  expect_output --from="$passthru" "$random_msg" "stdin was passed through"
+}