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How to Make
Kubernetes Controller Development Happier
mercari.go #17
Yuki Ito (@mrno110)
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Merpay / Mercoin
Architect Team
Mercari
Microservices Platform CI/CD
Yuki Ito
@mrno110
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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What is Kubernetes
Kubernetes is a portable,
extensible, open-source
platform for managing
containerized workloads and
services, that facilitates both
declarative con
fi
guration and
automation.
https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/
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Container Orchestration
👨💻
kube-apiserver
kubelet
Pod Pod Pod
Node
kubelet
Pod Pod Pod
Node
kubectl
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Container Orchestration
kubelet
containerd
runc
Container
Node
runc
Container
Container Runtime Interface (CRI)
runc
Container
Open Container Initiative (OCI) speci
fi
cation
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Container Orchestration
kubelet
containerd
runc
Container
Node
runc
Container
Container Runtime Interface (CRI)
runc
Container
Open Container Initiative (OCI) speci
fi
cation
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Create Container (Pod)
👨💻
kube-apiserver
kubectl
YAML
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Create Container (Pod)
--
-
apiVersion: v
1
kind: Po
d
metadata
:
name: envo
y
spec
:
containers
:
- name: envo
y
image: envoy:lates
t
command
:
- '...'
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Create Container (Pod)
kube-apiserver
Pod
etcd
Write Read
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Container Orchestration
👨💻
kube-apiserver
kubelet
Pod Pod Pod
Node
kubelet
Pod Pod Pod
Node
kubectl
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Controller Pattern
A controller tracks at least one
Kubernetes resource type.
These objects have a spec
fi
eld
that represents the desired
state. The controller(s) for that
resource are responsible for
making the current state come
closer to that desired state.
https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/
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e.g. Built-in Deployment Controller
--
-
apiVersion: apps/v
1
kind: Deploymen
t
spec
:
replicas:
3
template
:
spec
:
containers
:
- image: envoy:latest
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e.g. Built-in Deployment Controller
--
-
apiVersion: apps/v
1
kind: Deploymen
t
spec
:
replicas: 3
template
:
spec
:
containers
:
- image: envoy:latest
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e.g. Built-in Deployment Controller
Current Kubernetes Resource
Deployment (ReplicaSet) Controller
Desired Replicas: 3
Watch & Reconcile
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e.g. Built-in Deployment Controller
Current Kubernetes Resource
Deployment (ReplicaSet) Controller
Pod Pod Pod
Desired Replicas: 3
Watch & Reconcile
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e.g. Built-in Deployment Controller
Current Kubernetes Resource
Deployment (ReplicaSet) Controller
Pod Pod Pod
Desired Replicas: 3
Watch & Reconcile
❌
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e.g. Built-in Deployment Controller
Current Kubernetes Resource
Deployment (ReplicaSet) Controller
Pod Pod
Desired Replicas: 3
Watch & Reconcile
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e.g. Built-in Deployment Controller
Current Kubernetes Resource
Deployment (ReplicaSet) Controller
Pod Pod
Reconcile
Pod
Desired Replicas: 3
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Custom Kubernetes Controller
Current Kubernetes Resource
Custom Kubernetes Controller
Resource Resource Resource
Watch & Reconcile
Desired state
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e.g. Pull Request Replication Controller
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e.g. Pull Request Replication Controller
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e.g. Pull Request Replication Controller
https://events.merpay.com/techfest-2021/#day-5
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Custom Resource De
fi
nition (CRD)
ɾPod
ɾReplicaSet
ɾDeployment
ɾService
ɾIngress
ɾHorizontalPodAutoscaler
ɾPodDisruptionBudget ...
e.g. Istio
ɾVirtualService ...
e.g. spanner-autoscaler
ɾSpannerAutoscaler
e.g. CrossPlane
ɾCloudSQLInstance ...
Native Resources Custom Resources
+
Extends Kubernetes using CRD
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e.g. Istio
VirtualService
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e.g. spanner-autoscaler
https://github.com/mercari/spanner-autoscaler
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e.g. spanner-autoscaler
https://github.com/mercari/spanner-autoscaler
apiVersion: spanner.mercari.com/v1alpha
1
kind: SpannerAutoscale
r
metadata
:
name: spannerautoscale
r
namespace: xx
x
spec
:
scaleTargetRef
:
projectId: #...
instanceId: #...
minNodes:
5
maxNodes: 1
0
maxScaleDownNodes:
1
targetCPUUtilization
:
highPriority: 60
SpannerAutoscaler
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Custom Kubernetes Controller
Current Kubernetes Resource
Custom Kubernetes Controller
Resource Resource Resource
Watch & Reconcile
Desired state
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kubernetes / client-go
https://github.com/kubernetes/client-go
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kubernetes / client-go
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kubernetes-sigs / controller-runtime
https://github.com/kubernetes-sigs/controller-runtime
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kubernetes-sigs / controller-runtime
https://github.com/kubernetes-sigs/controller-runtime
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kubernetes-sigs / kubebuilder
https://github.com/kubernetes-sigs/kubebuilder
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kubernetes-sigs / kubebuilder
> kubebuilder init --domain tutorial.kubebuilder.io
> tree
.
.
├── confi
g
│ ├── defaul
t
│ │ ├── kustomization.yam
l
│ │ ├── manager_auth_proxy_patch.yam
l
│ │ └── manager_config_patch.yam
l
│ ├── manage
r
│ │ ├── controller_manager_config.yam
l
│ │ ├── kustomization.yam
l
│ │ └── manager.yam
l
│ ├── prometheu
s
│ │ ├── kustomization.yam
l
│ │ └── monitor.yam
l
│ └── rba
c
│ ├── auth_proxy_client_clusterrole.yam
l
│ ├── auth_proxy_role_binding.yam
l
│ ├── auth_proxy_role.yam
l
│ ├── auth_proxy_service.yam
l
│ ├── kustomization.yam
l
│ ├── leader_election_role_binding.yam
l
│ ├── leader_election_role.yam
l
│ ├── role_binding.yam
l
│ └── service_account.yam
l
├── Dockerfil
e
├── go.mo
d
├── go.su
m
├── hac
k
│ └── boilerplate.go.tx
t
├── main.g
o
├── Makefil
e
└── PROJECT
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Custom Resource De
fi
nition
--
-
kind: CustomResourceDefinitio
n
spec
:
names
:
kind: Repositor
y
listKind: RepositoryLis
t
plural: repositorie
s
singular: repositor
y
scope: Namespace
d
versions
:
- name: v1alpha
1
schema
:
openAPIV3Schema
:
properties
:
spec
:
properties
:
repository
:
type: string
CRD (YAML)
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Code Generation
--
-
kind: CustomResourceDefinitio
n
spec
:
names
:
kind: Repositor
y
listKind: RepositoryLis
t
plural: repositorie
s
singular: repositor
y
scope: Namespace
d
versions
:
- name: v1alpha
1
schema
:
openAPIV3Schema
:
properties
:
spec
:
properties
:
repository
:
type: string
CRD (YAML)
Go
func (in *Repository) DeepCopyObject() runtime.Object
{
if c := in.DeepCopy(); c != nil
{
return
c
}
return nil
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
type Repository struct
{
metav1.TypeMeta `json:",inline"`
metav1.ObjectMeta `json:"metadata,omitempty"`
Spec RepositorySpe
c
}
type RepositorySpec struct
{
Repository string `json:"repository,omitempty"`
}
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DeepCopyObject
client-go requires implementing DeepCopyObject
func (in *Repository) DeepCopyObject() runtime.Object
{
if c := in.DeepCopy(); c != nil
{
return
c
}
return nil
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
type Object interface
{
GetObjectKind() schema.ObjectKin
d
DeepCopyObject() Objec
t
}
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kubernetes-sigs / controller-tools (controller-gen)
--
-
kind: CustomResourceDefinitio
n
spec
:
names
:
kind: Repositor
y
listKind: RepositoryLis
t
plural: repositorie
s
singular: repositor
y
scope: Namespace
d
versions
:
- name: v1alpha
1
schema
:
openAPIV3Schema
:
properties
:
spec
:
properties
:
repository
:
type: string
CRD (YAML)
Go
func (in *Repository) DeepCopyObject() runtime.Object
{
if c := in.DeepCopy(); c != nil
{
return
c
}
return nil
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
type Repository struct
{
metav1.TypeMeta `json:",inline"`
metav1.ObjectMeta `json:"metadata,omitempty"`
Spec RepositorySpe
c
}
type RepositorySpec struct
{
Repository string `json:"repository,omitempty"`
}
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Code Generation
ɾDe
fi
nition should be language agnostic
ɾBut, do not want to write complex CRD YAML...
controller-gen is useful, however...
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Istio de
fi
nes CRDs as Protocol Bu
ff
ers
message VirtualService
{
repeated string hosts = 1
;
repeated string gateways = 2
;
repeated HTTPRoute http = 3
;
// ...
}
Protocol Bu
ff
ers
https://github.com/istio/api/blob/1.11.4/networking/v1beta1/virtual_service.proto
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De
fi
ne CRDs as Protocol Bu
ff
ers
message Repository
{
string owner = 1
;
string repository = 2
;
}
type Repository struct
{
state protoimpl.MessageStat
e
sizeCache protoimpl.SizeCach
e
unknownFields protoimpl.UnknownField
s
Owner string `protobuf:...`
Repository string `protobuf:...`
}
Protocol Bu
ff
ers
func (in *Repository) DeepCopyInto(out *Repository)
{
p := proto.Clone(in).(*Repository
)
*out = *
p
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
protoc-gen-go protoc-gen-deepcopy
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bufbuild / buf
https://buf.build/
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bufbuild / buf
--
-
version: v1beta
1
plugins
:
- name: g
o
path: ./bin/protoc-gen-g
o
out:
.
opt: paths=source_relativ
e
- name: deepcop
y
path: ./bin/protoc-gen-deepcop
y
out:
.
opt: paths=source_relative
buf.gen.yaml
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De
fi
ne CRDs as Protocol Bu
ff
ers
message Repository
{
string owner = 1
;
string repository = 2
;
}
type Repository struct
{
state protoimpl.MessageStat
e
sizeCache protoimpl.SizeCach
e
unknownFields protoimpl.UnknownField
s
Owner string `protobuf:...`
Repository string `protobuf:...`
}
Protocol Bu
ff
ers
func (in *Repository) DeepCopyInto(out *Repository)
{
p := proto.Clone(in).(*Repository
)
*out = *
p
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
protoc-gen-go protoc-gen-deepcopy
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De
fi
ne CRDs as Protocol Bu
ff
ers
message Repository
{
string owner = 1
;
string repository = 2
;
}
type Repository struct
{
state protoimpl.MessageStat
e
sizeCache protoimpl.SizeCach
e
unknownFields protoimpl.UnknownField
s
Owner string `protobuf:...`
Repository string `protobuf:...`
}
Protocol Bu
ff
ers
func (in *Repository) DeepCopyInto(out *Repository)
{
p := proto.Clone(in).(*Repository
)
*out = *
p
}
func (in *Repository) DeepCopy() *Repository
{
if in == nil
{
return nil
}
out := new(Repository
)
in.DeepCopyInto(out
)
return ou
t
}
protoc-gen-go protoc-gen-deepcopy
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istio / tools / protoc-gen-deepcopy
https://github.com/istio/tools/tree/master/cmd/protoc-gen-deepcopy
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Generic protoc-gen-deepcopy
https://github.com/protobuf-tools/protoc-gen-deepcopy
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De
fi
ne CRDs as Protocol Bu
ff
ers
type Repository struct
{
state protoimpl.MessageStat
e
sizeCache protoimpl.SizeCach
e
unknownFields protoimpl.UnknownField
s
Owner string `protobuf:...`
Repository string `protobuf:...`
}
Protocol Bu
ff
ers
protoc-gen-go
type Repository struct
{
v1.TypeMet
a
v1.ObjectMet
a
// Proto Buffer Struc
t
Spec apisv1alpha1.Repositor
y
}
kubetype-gen
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istio / tools / kubetype-gen
https://github.com/istio/tools/tree/master/cmd/kubetype-gen
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Generic kubetype-gen
https://github.com/110y/kubetype-gen
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De
fi
ne CRDs as Protocol Bu
ff
ers
type Repository struct
{
state protoimpl.MessageStat
e
sizeCache protoimpl.SizeCach
e
unknownFields protoimpl.UnknownField
s
Owner string `protobuf:...`
Repository string `protobuf:...`
}
Protocol Bu
ff
ers
protoc-gen-go
type Repository struct
{
v1.TypeMet
a
v1.ObjectMet
a
// Proto Buffer Struc
t
Spec apisv1alpha1.Repositor
y
}
kubetype-gen
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De
fi
ne CRDs as Protocol Bu
ff
ers
--
-
kind: CustomResourceDefinitio
n
spec
:
names
:
kind: Repositor
y
listKind: RepositoryLis
t
plural: repositorie
s
singular: repositor
y
scope: Namespace
d
versions
:
- name: v1alpha
1
schema
:
openAPIV3Schema
:
properties
:
spec
:
properties
:
repository
:
type: string
CRD (YAML)
type Repository struct
{
v1.TypeMet
a
v1.ObjectMet
a
// Proto Buffer Struc
t
Spec apisv1alpha1.Repositor
y
}
kubetype-gen
controller-gen
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De
fi
ne CRDs as Protocol Bu
ff
ers
Protocol Bu
ff
ers
protoc-gen-go / protoc-gen-deepcopy
Protocol Bu
ff
er Go Struct (+ DeepCopy)
Kubernetes Go Types
Custom Resource De
fi
nitions (YAML)
kubetype-gen
controller-gen
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De
fi
ne CRDs as Protocol Bu
ff
ers
Protocol Bu
ff
ers
Advanced
Custom Resource De
fi
nitions (YAML)
istio /tools / cue-gen
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Kubernetes Architecture
👨💻
kube-apiserver
kubelet
Pod Pod Pod
Node
kubelet
Pod Pod Pod
Node
kubectl
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Kubernetes Architecture
kube-apiserver
Resource
etcd
Write Read
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Kubernetes Architecture
kube-apiserver
etcd
Write Read
Kubernetes Controller
Write Read
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Kubernetes Architecture
kube-apiserver
etcd
Write Read
Kubernetes Controller
Write Read
Like Database
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envtest
https://pkg.go.dev/sigs.k8s.io/controller-runtime/pkg/envtest
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setup-envtest
https://github.com/kubernetes-sigs/controller-runtime/tree/master/tools/setup-envtest
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setup-envtest
> setup-envtest use
Version: 1.22.
1
OS/Arch: linux/amd6
4
Path: /path/to/kubebuilder-envtest/k8s/1.22.1-linux-amd6
4
> ls /path/to/kubebuilder-envtest/k8s/1.22.1-linux-amd6
4
etcd kube-apiserver kubectl
https://github.com/kubernetes-sigs/controller-runtime/tree/master/tools/setup-envtest
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Unit Testing with envtest
et := envtest.Environment
{
BinaryAssetsDirectory: "/path/to/envtest-binaries"
,
CRDDirectoryPaths: []string{"/path/to/crd-yamls"}
,
ControlPlaneStartTimeout: 20 * time.Second
,
ErrorIfCRDPathMissing: true
,
AttachControlPlaneOutput: false
,
KubeAPIServerFlags: []string
{
"--advertise-address=127.0.0.1"
,
// ...
}
,
}
cfg, err := et.Start(
)
if err != nil
{
return nil, nil, fmt.Errorf("failed to start envtest: %w", err
)
}
cli, err := client.New(cfg, client.Options
{
// ...
})
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Unit Testing with envtest
ɾSpinning up takes 10s~
envtest is useful, however...
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Unit Testing with envtest
Caching envtest instance with TestMain
func TestMain(m *testing.M)
{
os.Exit(func() int
{
cli, done, err := testutil.TestK8SClient()
if err != nil
{
fmt.Fprintf(os.Stdout, "failed to create k8s client: %s\n", err
)
return 1
}
defer done(
)
k8sClient = cl
i
return m.Run(
)
}()
)
}
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Unit Testing with envtest
func TestXxx(t *testing.T)
{
t.Parallel(
)
//...
k8sClient.Create(...
)
}
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Unit Testing with envtest
Isolating each test by creating dedicated Namespaces
func TestXxx(t *testing.T)
{
// ...
namespace := NewNamespace(t, ctx, k8sClient
)
}
func NewNamespace(t *testing.T, ctx context.Context, cli client.Client) string
{
t.Helper(
)
name := uuid.New().String(
)
ns := &corev1.Namespace
{
ObjectMeta: metav1.ObjectMeta
{
Name: name
,
}
,
}
if err := cli.Create(ctx, ns); err != nil
{
t.Fatalf("failed to create namespace: %s", err
)
}
return nam
e
}
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Kubernetes Architecture
kube-apiserver
etcd
Write Read
Kubernetes Controller
Write Read
Like Database
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging
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Using kind for Local Development
https://github.com/kubernetes-sigs/kind
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Ska
ff
old
https://ska
ff
old.dev/
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Ska
ff
old + kind
👨💻
kind cluster
ska
ff
old run
Controller (Image)
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Ska
ff
old + kind
# ...
spec
:
containers
:
- args
:
- /usr/bin/my-controller
Pod Spec
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Ska
ff
old + kind
👨💻
kind cluster
ska
ff
old run
Controller (Image)
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ska
ff
old debug
👨💻
kind cluster
ska
ff
old debug
Controller (Image) + Debugger (Delve)
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ska
ff
old debug
# ...
spec
:
containers
:
- args
:
- /dbg/go/bin/dlv
- exe
c
- --headles
s
- --listen=:56268
- ..
.
- /usr/bin/my-controlle
r
# ...
volumeMounts
:
- mountPath: /db
g
# ...
initContainers
:
- image: gcr.io/gcp-dev-tools/duct-tape/g
o
# ...
Pod Spec
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ska
ff
old debug
# ...
spec
:
containers
:
- args
:
- /dbg/go/bin/dl
v
- exe
c
- --headles
s
- --listen=:5626
8
- ..
.
- /usr/bin/my-controlle
r
# ...
volumeMounts
:
- mountPath: /db
g
# ...
initContainers
:
- image: gcr.io/gcp-dev-tools/duct-tape/g
o
# ...
Pod Spec
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Delve
https://github.com/go-delve/delve
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ska
ff
old debug
# ...
spec
:
containers
:
- args
:
- /dbg/go/bin/dlv
- exe
c
- --headles
s
- --listen=:56268
- ..
.
- /usr/bin/my-controlle
r
# ...
volumeMounts
:
- mountPath: /db
g
# ..
.
initContainers
:
- image: gcr.io/gcp-dev-tools/duct-tape/g
o
# ...
Pod Spec
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ska
ff
old debug
👨💻
kind cluster
ska
ff
old debug
Controller (Image) + Debugger (Delve)
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ska
ff
old debug
https://gihyo.jp/magazine/SD/archive/2020/202008
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Agenda
ɾWhat is Kubernetes Controller
ɾCode Generation
ɾTesting
ɾDebugging