Redhat/CentOS fixes per code review

* Always read /etc/redhat-release (symlinked on CentOS)
* Make _rhel_family the tag name, not _centos_family
* Add comment about writing to "system" systemd area

docs/images.md

@@ -32,7 +32,7 @@ In addition, we support a few-well known aliases for the owner:
 
 
 
-## Centos
+## CentOS
 
 CentOS7 support is still experimental.
 
@@ -40,6 +40,7 @@ The following steps are known:
 
 * Accept the agreement at http://aws.amazon.com/marketplace/pp?sku=aw0evgkw8e5c1q413zgy5pjce
 * Specify the AMI by id (there are no tags): us-east-1: ami-6d1c2007
+* CentOS7 AMIs are running an older kernel than we prefer to run elsewhere
 
 ## RHEL7
 
@@ -48,3 +49,4 @@ RHEL7 support is still experimental.
 The following steps are known:
 
 * Specify the AMI by id (there are no tags): us-east-1: ami-2051294a
+* RHEL7 AMIs are running an older kernel than we prefer to run elsewhere

upup/pkg/fi/nodeup/nodetasks/package.go

@@ -94,7 +94,7 @@ func (e *Package) Find(c *fi.Context) (*Package, error) {
 		return e.findDpkg(c)
 	}
 
-	if target.HasTag(tags.TagOSFamilyCentos) {
+	if target.HasTag(tags.TagOSFamilyRHEL) {
 		return e.findYum(c)
 	}
 
@@ -252,7 +252,7 @@ func (_ *Package) RenderLocal(t *local.LocalTarget, a, e, changes *Package) erro
 			var args []string
 			if t.HasTag(tags.TagOSFamilyDebian) {
 				args = []string{"dpkg", "-i", local}
-			} else if t.HasTag(tags.TagOSFamilyCentos) {
+			} else if t.HasTag(tags.TagOSFamilyRHEL) {
 				args = []string{"/usr/bin/rpm", "-i", local}
 			} else {
 				return fmt.Errorf("unsupported package system")
@@ -268,7 +268,7 @@ func (_ *Package) RenderLocal(t *local.LocalTarget, a, e, changes *Package) erro
 			if t.HasTag(tags.TagOSFamilyDebian) {
 				args = []string{"apt-get", "install", "--yes", e.Name}
 
-			} else if t.HasTag(tags.TagOSFamilyCentos) {
+			} else if t.HasTag(tags.TagOSFamilyRHEL) {
 				args = []string{"/usr/bin/yum", "install", "-y", e.Name}
 			} else {
 				return fmt.Errorf("unsupported package system")
@@ -293,9 +293,9 @@ func (_ *Package) RenderLocal(t *local.LocalTarget, a, e, changes *Package) erro
 				}
 
 				changes.Healthy = nil
-			} else if t.HasTag(tags.TagOSFamilyCentos) {
-				// We can't reach here anyway...
-				return fmt.Errorf("package repair not supported on centos")
+			} else if t.HasTag(tags.TagOSFamilyRHEL) {
+				// Not set on TagOSFamilyRHEL, we can't currently reach here anyway...
+				return fmt.Errorf("package repair not supported on RHEL/CentOS")
 			} else {
 				return fmt.Errorf("unsupported package system")
 			}

upup/pkg/fi/nodeup/nodetasks/service.go

@@ -20,6 +20,10 @@ import (
 
 const (
 	debianSystemdSystemPath = "/lib/systemd/system"
+
+	// TODO: Generally only repo packages write to /usr/lib/systemd/system on _rhel_family
+	// But we use it in two ways: we update the docker manifest, and we install our own
+	// package (protokube, kubelet).  Maybe we should have the idea of a "system" package.
 	centosSystemdSystemPath = "/usr/lib/systemd/system"
 )
 
@@ -114,7 +118,7 @@ func getSystemdStatus(name string) (map[string]string, error) {
 func (e *Service) systemdSystemPath(target tags.HasTags) (string, error) {
 	if target.HasTag(tags.TagOSFamilyDebian) {
 		return debianSystemdSystemPath, nil
-	} else if target.HasTag(tags.TagOSFamilyCentos) {
+	} else if target.HasTag(tags.TagOSFamilyRHEL) {
 		return centosSystemdSystemPath, nil
 	} else {
 		return "", fmt.Errorf("unsupported systemd system")

upup/pkg/fi/nodeup/tags.go

@@ -40,27 +40,17 @@ func FindOSTags(rootfs string) ([]string, error) {
 		glog.Warningf("error reading /etc/debian_version: %v", err)
 	}
 
-	// Centos has /etc/centos-release
-	centosRelease, err := ioutil.ReadFile(path.Join(rootfs, "etc/centos-release"))
-	if err == nil {
-		for _, line := range strings.Split(string(centosRelease), "\n") {
-			line = strings.TrimSpace(line)
-			if strings.HasPrefix(line, "CentOS Linux release 7.") {
-				return []string{"_centos7", tags.TagOSFamilyCentos, tags.TagSystemd}, nil
-			}
-		}
-		glog.Warningf("unhandled centos-release info %q", string(lsbRelease))
-	} else if !os.IsNotExist(err) {
-		glog.Warningf("error reading /etc/centos-release: %v", err)
-	}
-
 	// Redhat has /etc/redhat-release
+	// Centos has /etc/centos-release
 	redhatRelease, err := ioutil.ReadFile(path.Join(rootfs, "etc/redhat-release"))
 	if err == nil {
 		for _, line := range strings.Split(string(redhatRelease), "\n") {
 			line = strings.TrimSpace(line)
 			if strings.HasPrefix(line, "Red Hat Enterprise Linux Server release 7.") {
-				return []string{"_rhel7", tags.TagOSFamilyCentos, tags.TagSystemd}, nil
+				return []string{"_rhel7", tags.TagOSFamilyRHEL, tags.TagSystemd}, nil
+			}
+			if strings.HasPrefix(line, "CentOS Linux release 7.") {
+				return []string{"_centos7", tags.TagOSFamilyRHEL, tags.TagSystemd}, nil
 			}
 		}
 		glog.Warningf("unhandled redhat-release info %q", string(lsbRelease))

upup/pkg/fi/nodeup/tags/tags.go

@@ -1,7 +1,7 @@
 package tags
 
 const (
-	TagOSFamilyCentos = "_centos_family"
+	TagOSFamilyRHEL   = "_rhel_family"
 	TagOSFamilyDebian = "_debian_family"
 
 	TagSystemd = "_systemd"