packages/coredns-deployment
1
0
Fork 0
mirror of https://github.com/notherealmarco/coredns-deployment.git synced 2025-05-05 12:32:34 +02:00
Code Issues Projects Releases Packages 1 Wiki Activity Actions

kubernetes/migration: support simple downgrade cases (#172)

Browse source 
* support basic downgrades

* add unit test for validDownMigration

* add no-op test for downward migration

* document
This commit is contained in:
Chris O'Haver 2019-05-20 16:11:03 -04:00 • committed by GitHub
parent 487cb8878d
commit 38ae5466f7
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
4 changed files with 264 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

13
kubernetes/migration/README.md
View file

@ -30,15 +30,22 @@ any new default plugins that would be added in a migration. Notices
`Migrate(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string, deprecations bool) (string, error)`
Migrate returns a migrated version of the Corefile, or an error if it cannot. It will:
Migrate returns a migrated version of the Corefile, or an error if it cannot. The _to_ version
must be >= the _from_ version. It will:
* replace/convert any plugins/options that have replacements (e.g. _proxy_ -> _forward_)
* return an error if replacable plugins/options cannot be converted (e.g. proxy _options_ not available in _forward_)
* remove plugins/options that do not have replacements (e.g. kubernetes `upstream`)
* add in any new default plugins where applicable if they are not already present (e.g. adding _loop_ plugin when it was added).
This will have to be case by case, and could potentially get complicated.
* add in any new default plugins where applicable if they are not already present.
* If deprecations is true, deprecated plugins/options will be migrated as soon as they are deprecated.
* If deprecations is false, deprecated plugins/options will be migrated only once they become removed or ignored.
`MigrateDown(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string) (string, error)`
MigrateDown returns a downward migrated version of the Corefile, or an error if it cannot. The _to_ version
must be <= the _from_ version.
* It will handle the removal of plugins and options that no longer exist in the destination
version when downgrading.
* It will not restore plugins/options that might have been removed or altered during an upward migration.
`Unsupported(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string) ([]Notice, error)`

108
kubernetes/migration/migrate.go
View file

@ -29,7 +29,7 @@ func getStatus(fromCoreDNSVersion, toCoreDNSVersion, corefileStr, status string)
if fromCoreDNSVersion == toCoreDNSVersion {
return nil, nil
}
err := validateVersions(fromCoreDNSVersion, toCoreDNSVersion)
err := validUpMigration(fromCoreDNSVersion, toCoreDNSVersion)
if err != nil {
return nil, err
}
@ -125,14 +125,15 @@ func getStatus(fromCoreDNSVersion, toCoreDNSVersion, corefileStr, status string)
return notices, nil
}
// Migrate returns the Corefile converted to toCoreDNSVersion, or an error if it cannot.
// Migrate returns the Corefile converted to toCoreDNSVersion, or an error if it cannot. This function only accepts
// a forward migration, where the destination version is => the start version.
// If deprecations is true, deprecated plugins/options will be migrated as soon as they are deprecated.
// If deprecations is false, deprecated plugins/options will be migrated only once they become removed or ignored.
func Migrate(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string, deprecations bool) (string, error) {
if fromCoreDNSVersion == toCoreDNSVersion {
return corefileStr, nil
}
err := validateVersions(fromCoreDNSVersion, toCoreDNSVersion)
err := validUpMigration(fromCoreDNSVersion, toCoreDNSVersion)
if err != nil {
return "", err
}
@ -254,6 +255,89 @@ func Migrate(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string, deprecati
return cf.ToString(), nil
}
// MigrateDown returns the Corefile converted to toCoreDNSVersion, or an error if it cannot. This function only accepts
// a downward migration, where the destination version is <= the start version.
func MigrateDown(fromCoreDNSVersion, toCoreDNSVersion, corefileStr string) (string, error) {
if fromCoreDNSVersion == toCoreDNSVersion {
return corefileStr, nil
}
err := validDownMigration(fromCoreDNSVersion, toCoreDNSVersion)
if err != nil {
return "", err
}
cf, err := corefile.New(corefileStr)
if err != nil {
return "", err
}
v := fromCoreDNSVersion
for {
newSrvs := []*corefile.Server{}
for _, s := range cf.Servers {
newPlugs := []*corefile.Plugin{}
for _, p := range s.Plugins {
vp, present := Versions[v].plugins[p.Name]
if !present {
newPlugs = append(newPlugs, p)
continue
}
if vp.downAction == nil {
newPlugs = append(newPlugs, p)
continue
}
p, err := vp.downAction(p)
if err != nil {
return "", err
}
if p == nil {
// remove plugin, skip options processing
continue
}
newOpts := []*corefile.Option{}
for _, o := range p.Options {
vo, present := Versions[v].plugins[p.Name].options[o.Name]
if !present {
newOpts = append(newOpts, o)
continue
}
if vo.downAction == nil {
newOpts = append(newOpts, o)
continue
}
o, err := vo.downAction(o)
if err != nil {
return "", err
}
if o == nil {
// remove option
continue
}
newOpts = append(newOpts, o)
}
newPlug := &corefile.Plugin{
Name: p.Name,
Args: p.Args,
Options: newOpts,
}
newPlugs = append(newPlugs, newPlug)
}
newSrv := &corefile.Server{
DomPorts: s.DomPorts,
Plugins: newPlugs,
}
newSrvs = append(newSrvs, newSrv)
}
cf = &corefile.Corefile{Servers: newSrvs}
if v == toCoreDNSVersion {
break
}
v = Versions[v].priorVersion
}
return cf.ToString(), nil
}
// Default returns true if the Corefile is the default for a given version of Kubernetes.
// Or, if k8sVersion is empty, Default returns true if the Corefile is the default for any version of Kubernetes.
func Default(k8sVersion, corefileStr string) bool {
@ -330,7 +414,7 @@ func validateVersion(fromCoreDNSVersion string) error {
return nil
}
func validateVersions(fromCoreDNSVersion, toCoreDNSVersion string) error {
func validUpMigration(fromCoreDNSVersion, toCoreDNSVersion string) error {
err := validateVersion(fromCoreDNSVersion)
if err != nil {
return err
@ -341,5 +425,19 @@ func validateVersions(fromCoreDNSVersion, toCoreDNSVersion string) error {
}
return nil
}
return fmt.Errorf("cannot migrate to '%v' from '%v'", toCoreDNSVersion, fromCoreDNSVersion)
return fmt.Errorf("cannot migrate up to '%v' from '%v'", toCoreDNSVersion, fromCoreDNSVersion)
}
func validDownMigration(fromCoreDNSVersion, toCoreDNSVersion string) error {
err := validateVersion(fromCoreDNSVersion)
if err != nil {
return err
}
for prior := Versions[fromCoreDNSVersion].priorVersion; prior != ""; prior = Versions[prior].priorVersion {
if prior != toCoreDNSVersion {
continue
}
return nil
}
return fmt.Errorf("cannot migrate down to '%v' from '%v'", toCoreDNSVersion, fromCoreDNSVersion)
}

132
kubernetes/migration/migrate_test.go
View file

@ -242,6 +242,108 @@ mystub-2.example.org {
}
}
func TestMigrateDown(t *testing.T) {
testCases := []struct {
name string
fromVersion string
toVersion string
deprecations bool
startCorefile string
expectedCorefile string
}{
{
name: "from 1.5.0 to 1.1.3",
fromVersion: "1.5.0",
toVersion: "1.1.3",
startCorefile: `.:53 {
errors
health
ready
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
`,
expectedCorefile: `.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
reload
loadbalance
}
`,
},
{
name: "no-op same version migration",
fromVersion: "1.3.1",
toVersion: "1.3.1",
deprecations: true,
startCorefile: `.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
`,
expectedCorefile: `.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
`,
},
}
for _, testCase := range testCases {
t.Run(testCase.name, func(t *testing.T) {
result, err := MigrateDown(testCase.fromVersion, testCase.toVersion, testCase.startCorefile)
if err != nil {
t.Errorf("%v", err)
}
if result != testCase.expectedCorefile {
t.Errorf("expected -> got diffs:\n%v", diff.LineDiff(testCase.expectedCorefile, result))
}
})
}
}
func TestDeprecated(t *testing.T) {
startCorefile := `.:53 {
errors
@ -418,7 +520,7 @@ stubzone.org:53 {
}
}
func TestValidateVersions(t *testing.T) {
func TestValidUpMigration(t *testing.T) {
testCases := []struct {
from string
to string
@ -433,7 +535,33 @@ func TestValidateVersions(t *testing.T) {
}
for _, tc := range testCases {
err := validateVersions(tc.from, tc.to)
err := validUpMigration(tc.from, tc.to)
if !tc.shouldErr && err != nil {
t.Errorf("expected '%v' to '%v' to be valid versions.", tc.from, tc.to)
}
if tc.shouldErr && err == nil {
t.Errorf("expected '%v' to '%v' to be invalid versions.", tc.from, tc.to)
}
}
}
func TestValidDownMigration(t *testing.T) {
testCases := []struct {
from string
to string
shouldErr bool
}{
{"1.3.1", "1.3.1", true},
{"1.3.1", "1.5.0", true},
{"1.5.0", "1.3.1", false},
{"banana", "1.5.0", true},
{"1.3.1", "apple", true},
{"banana", "apple", true},
}
for _, tc := range testCases {
err := validDownMigration(tc.from, tc.to)
if !tc.shouldErr && err != nil {
t.Errorf("expected '%v' to '%v' to be valid versions.", tc.from, tc.to)

23
kubernetes/migration/versions.go
View file

@ -12,19 +12,22 @@ type plugin struct {
options map[string]option
action pluginActionFn // action affecting this plugin only
add serverActionFn // action to add a new plugin to the server block
downAction pluginActionFn // downgrade action affecting this plugin only
}
type option struct {
status string
replacedBy string
additional string
action optionActionFn // take action affecting this option only
add pluginActionFn // take action to add the option to the plugin
action optionActionFn // action affecting this option only
add pluginActionFn // action to add the option to the plugin
downAction optionActionFn // downgrade action affecting this option only
}
type release struct {
k8sRelease string
nextVersion string
priorVersion string
dockerImageSHA string
plugins map[string]plugin // list of plugins with deprecation status and migration actions
@ -88,6 +91,8 @@ func addToAllServerBlocks(sb *corefile.Server, newPlugin *corefile.Plugin) (*cor
var Versions = map[string]release{
"1.5.0": {
priorVersion: "1.4.0",
k8sRelease: "1.15",
dockerImageSHA: "e83beb5e43f8513fa735e77ffc5859640baea30a882a11cc75c4c3244a737d3c",
plugins: map[string]plugin{
"errors": {
@ -106,6 +111,7 @@ var Versions = map[string]release{
add: func(c *corefile.Server) (*corefile.Server, error) {
return addToKubernetesServerBlocks(c, &corefile.Plugin{Name: "ready"})
},
downAction: removePlugin,
},
"autopath": {},
"kubernetes": {
@ -176,6 +182,7 @@ var Versions = map[string]release{
},
"1.4.0": {
nextVersion: "1.5.0",
priorVersion: "1.3.1",
dockerImageSHA: "70a92e9f6fc604f9b629ca331b6135287244a86612f550941193ec7e12759417",
plugins: map[string]plugin{
"errors": {
@ -255,6 +262,7 @@ var Versions = map[string]release{
},
"1.3.1": {
nextVersion: "1.4.0",
priorVersion: "1.3.0",
k8sRelease: "1.14",
dockerImageSHA: "02382353821b12c21b062c59184e227e001079bb13ebd01f9d3270ba0fcbf1e4",
defaultConf: `.:53 {
@ -351,6 +359,7 @@ var Versions = map[string]release{
},
"1.3.0": {
nextVersion: "1.3.1",
priorVersion: "1.2.6",
dockerImageSHA: "e030773c7fee285435ed7fc7623532ee54c4c1c4911fb24d95cd0170a8a768bc",
plugins: map[string]plugin{
"errors": {
@ -384,6 +393,7 @@ var Versions = map[string]release{
},
},
"k8s_external": {
downAction: removePlugin,
options: map[string]option{
"apex": {},
"ttl": {},
@ -428,6 +438,7 @@ var Versions = map[string]release{
},
"1.2.6": {
nextVersion: "1.3.0",
priorVersion: "1.2.5",
k8sRelease: "1.13",
dockerImageSHA: "81936728011c0df9404cb70b95c17bbc8af922ec9a70d0561a5d01fefa6ffa51",
defaultConf: `.:53 {
@ -515,6 +526,7 @@ var Versions = map[string]release{
},
"1.2.5": {
nextVersion: "1.2.6",
priorVersion: "1.2.4",
dockerImageSHA: "33c8da20b887ae12433ec5c40bfddefbbfa233d5ce11fb067122e68af30291d6",
plugins: map[string]plugin{
"errors": {},
@ -582,6 +594,7 @@ var Versions = map[string]release{
},
"1.2.4": {
nextVersion: "1.2.5",
priorVersion: "1.2.3",
dockerImageSHA: "a0d40ad961a714c699ee7b61b77441d165f6252f9fb84ac625d04a8d8554c0ec",
plugins: map[string]plugin{
"errors": {},
@ -649,6 +662,7 @@ var Versions = map[string]release{
},
"1.2.3": {
nextVersion: "1.2.4",
priorVersion: "1.2.2",
dockerImageSHA: "12f3cab301c826978fac736fd40aca21ac023102fd7f4aa6b4341ae9ba89e90e",
plugins: map[string]plugin{
"errors": {},
@ -716,6 +730,7 @@ var Versions = map[string]release{
},
"1.2.2": {
nextVersion: "1.2.3",
priorVersion: "1.2.1",
k8sRelease: "1.12",
dockerImageSHA: "3e2be1cec87aca0b74b7668bbe8c02964a95a402e45ceb51b2252629d608d03a",
defaultConf: `.:53 {
@ -798,6 +813,7 @@ var Versions = map[string]release{
},
"1.2.1": {
nextVersion: "1.2.2",
priorVersion: "1.2.0",
dockerImageSHA: "fb129c6a7c8912bc6d9cc4505e1f9007c5565ceb1aa6369750e60cc79771a244",
plugins: map[string]plugin{
"errors": {},
@ -862,6 +878,7 @@ var Versions = map[string]release{
add: func(s *corefile.Server) (*corefile.Server, error) {
return addToForwardingServerBlocks(s, &corefile.Plugin{Name: "loop"})
},
downAction: removePlugin,
},
"reload": {},
"loadbalance": {},
@ -869,6 +886,7 @@ var Versions = map[string]release{
},
"1.2.0": {
nextVersion: "1.2.1",
priorVersion: "1.1.4",
dockerImageSHA: "ae69a32f8cc29a3e2af9628b6473f24d3e977950a2cb62ce8911478a61215471",
plugins: map[string]plugin{
"errors": {},
@ -937,6 +955,7 @@ var Versions = map[string]release{
},
"1.1.4": {
nextVersion: "1.2.0",
priorVersion: "1.1.3",
dockerImageSHA: "463c7021141dd3bfd4a75812f4b735ef6aadc0253a128f15ffe16422abe56e50",
plugins: map[string]plugin{
"errors": {},