NATS Operator
NATS Operator manages NATS clusters atop Kubernetes, automating their creation and administration.
Requirements
- Kubernetes v1.8+
Getting Started
The current version of the operator creates a NatsCluster
Custom Resources Definition
(CRD) under the nats.io
API group, to which you can make requests to
create NATS clusters.
To add the NatsCluster
and NATS Operator to your cluster you can run:
$ kubectl apply -f https://raw.githubusercontent.com/nats-io/nats-operator/master/deploy/default-rbac.yaml
$ kubectl apply -f https://raw.githubusercontent.com/nats-io/nats-operator/master/deploy/deployment.yaml
You will then be able to confirm that there is a new CRD registered in the cluster:
$ kubectl get crd
NAME AGE
natsclusters.nats.io 1s
An example of creating a 3 node cluster is below. The NATS operator will be responsible of assembling the cluster and replacing pods in case of failures.
echo '
apiVersion: "nats.io/v1alpha2"
kind: "NatsCluster"
metadata:
name: "example-nats-cluster"
spec:
size: 3
version: "1.3.0"
' | kubectl apply -f -
To list all the NATS clusters:
$ kubectl get natsclusters.nats.io
NAME AGE
example-nats-cluster 1s
Helm support
There is an alternative way to install NATS Operator for Helm users. You can go to helm/nats-operator and use the Helm charts found in the repo.
Installing NATS Operator on a Custom Namespace with RBAC enabled
In order to install the NATS Operator in a custom namespace, if RBAC
is enabled it is then necessary to create a ServiceAccount
and
ClusterRoleBinding
referring to the custom namespace in order for
the operator to be able run properly.
The example below will deploy the nats-operator
under the nats-io
namespace,
using the nats-operator
ServiceAccount:
$ kubectl create namespace nats-io
$ echo '
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: nats-operator
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: nats-operator-binding
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: nats-operator
subjects:
- kind: ServiceAccount
name: nats-operator
namespace: nats-io
' | kubectl -n nats-io apply -f -
$ kubectl -n nats-io apply -f https://raw.githubusercontent.com/nats-io/nats-operator/master/deploy/role.yaml
$ kubectl -n nats-io apply -f https://raw.githubusercontent.com/nats-io/nats-operator/master/deploy/deployment.yaml
$ kubectl -n nats-io logs deployment/nats-operator
time="2018-10-25T03:04:58Z" level=info msg="nats-operator Version: 0.2.3-v1alpha2+git"
Note that the NATS operator only monitors the NatsCluster
resources
which are created in the namespace where it was deployed, so if you
want to create a cluster you have to specify the same one as the
operator:
$ kubectl -n nats-io apply -f example/example-nats-cluster.yaml
natscluster "example-nats-1" created
$ kubectl -n nats-io get natsclusters
NAME AGE
example-nats-1 6m
$ kubectl -n nats-io get pods -l nats_cluster=example-nats-1
NAME READY STATUS RESTARTS AGE
example-nats-1-1 1/1 Running 0 7m
example-nats-1-2 1/1 Running 0 7m
example-nats-1-3 1/1 Running 0 6m
TLS support
By using a pair of opaque secrets (one for the clients and then another for the routes), it is possible to set TLS for the communication between the clients and also for the transport between the routes:
apiVersion: "nats.io/v1alpha2"
kind: "NatsCluster"
metadata:
name: "nats"
spec:
# Number of nodes in the cluster
size: 3
version: "1.3.0"
tls:
# Certificates to secure the NATS client connections:
serverSecret: "nats-clients-tls"
# Certificates to secure the routes.
routesSecret: "nats-routes-tls"
In order for TLS to be properly established between the nodes, it is necessary to create a wildcard certificate that matches the subdomain created for the service from the clients and the one for the routes.
The routesSecret
has to provide the files: ca.pem
, route-key.pem
, route.pem
,
for the CA, server private and public key respectively.
$ kubectl create secret generic nats-routes-tls --from-file=ca.pem --from-file=route-key.pem --from-file=route.pem
Similarly, the serverSecret
has to provide the files: ca.pem
, server-key.pem
, and server.pem
for the CA, server private key and public key used to secure the connection
with the clients.
$ kubectl create secret generic nats-clients-tls --from-file=ca.pem --from-file=server-key.pem --from-file=server.pem
Authorization
Using ServiceAccounts
The NATS Operator can define permissions based on Roles by using any
present ServiceAccount in a namespace. To use this feature, it is
necessary to use a Kubernetes +v1.10 cluster with the TokenRequest
and PodShareProcessNamespace
feature flags enabled. To try this
feature using minikube
you can configure it to start as follows:
minikube start \
--feature-gates="TokenRequest=true,PodShareProcessNamespace=true" \
--extra-config=apiserver.service-account-signing-key-file=/var/lib/localkube/certs/apiserver.key \
--extra-config=apiserver.service-account-issuer=api \
--extra-config=apiserver.service-account-api-audiences=api \
--extra-config=apiserver.service-account-key-file=/var/lib/localkube/certs/sa.pub
ServiceAccounts integration can then be enabled by setting the
enableServiceAccounts
flag to true in the NatsCluster
configuration.
---
apiVersion: nats.io/v1alpha2
kind: NatsCluster
metadata:
name: example-nats
spec:
size: 3
version: "1.3.0"
pod:
enableConfigReload: true
auth:
enableServiceAccounts: true
Permissions for a ServiceAccount
can be set by creating a
NatsServiceRole
for that account. In the example below, there are
two accounts, one is an admin user that has more permissions.
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: nats-admin-user
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: nats-user
---
apiVersion: nats.io/v1alpha2
kind: NatsServiceRole
metadata:
name: nats-user
namespace: nats-io
# Specifies which NATS cluster will be mapping this account.
labels:
nats_cluster: example-nats
spec:
permissions:
publish: ["foo.*", "foo.bar.quux"]
subscribe: ["foo.bar"]
---
apiVersion: nats.io/v1alpha2
kind: NatsServiceRole
metadata:
name: nats-admin-user
namespace: nats-io
labels:
nats_cluster: example-nats
spec:
permissions:
publish: [">"]
subscribe: [">"]
The above will create two different Secrets which can then be mounted as volumes for a Pod.
$ kubectl -n nats-io get secrets
NAME TYPE DATA AGE
...
nats-admin-user-example-nats-bound-token Opaque 1 43m
nats-user-example-nats-bound-token Opaque 1 43m
An example of mounting the secret in a Pod
can be found below:
---
apiVersion: v1
kind: Pod
metadata:
name: nats-user-pod
labels:
nats_cluster: example-nats
spec:
volumes:
- name: "token"
projected:
sources:
- secret:
name: "nats-user-example-nats-bound-token"
items:
- key: token
path: "token"
restartPolicy: Never
containers:
- name: nats-ops
command: ["/bin/sh"]
image: "wallyqs/nats-ops:latest"
tty: true
stdin: true
stdinOnce: true
volumeMounts:
- name: "token"
mountPath: "/var/run/secrets/nats.io"
Then within the Pod
the token can be used to authenticate against
the server using the created token.
$ kubectl -n nats-io attach -it nats-user-pod
/go # nats-sub -s nats://nats-user:`cat /var/run/secrets/nats.io/token`@example-nats:4222 hello.world
Listening on [hello.world]
^C
/go # nats-sub -s nats://nats-admin-user:`cat /var/run/secrets/nats.io/token`@example-nats:4222 hello.world
Can't connect: nats: authorization violation
Using a single secret with the explicit configuration.
Authorization can also be set for the server by using a secret where the permissions are defined in JSON:
{
"users": [
{ "username": "user1", "password": "secret1" },
{ "username": "user2", "password": "secret2",
"permissions": {
"publish": ["hello.*"],
"subscribe": ["hello.world"]
}
}
],
"default_permissions": {
"publish": ["SANDBOX.*"],
"subscribe": ["PUBLIC.>"]
}
}
Example of creating a secret to set the permissions:
kubectl create secret generic nats-clients-auth --from-file=clients-auth.json
Now when creating a NATS cluster it is possible to set the permissions as in the following example:
apiVersion: "nats.io/v1alpha2"
kind: "NatsCluster"
pmetadata:
name: "example-nats-auth"
spec:
size: 3
version: "1.1.0"
auth:
# Definition in JSON of the users permissions
clientsAuthSecret: "nats-clients-auth"
# How long to wait for authentication
clientsAuthTimeout: 5
Configuration Reload
On Kubernetes +v1.10 clusters that have been started with support for
sharing the process namespace (via --feature-gates=PodShareProcessNamespace=true
),
it is possible to enable on-the-fly reloading of configuration for the
servers that are part of the cluster. This can also be combined with the
authorization support, so in case the user permissions change, then the
servers will reload and apply the new permissions.
apiVersion: "nats.io/v1alpha2"
kind: "NatsCluster"
metadata:
name: "example-nats-auth"
spec:
size: 3
version: "1.1.0"
pod:
# Enable on-the-fly NATS Server config reload
# Note: only supported in Kubernetes clusters with PID namespace sharing enabled.
enableConfigReload: true
# Possible to customize version of reloader image
reloaderImage: connecteverything/nats-server-config-reloader
reloaderImageTag: "0.2.2-v1alpha2"
reloaderImagePullPolicy: "IfNotPresent"
auth:
# Definition in JSON of the users permissions
clientsAuthSecret: "nats-clients-auth"
# How long to wait for authentication
clientsAuthTimeout: 5
Development
Building the Docker Image
To build the nats-operator
Docker image:
$ docker build -f docker/operator/Dockerfile . <image:tag>
To build the nats-server-config-reloader
:
$ docker build -f docker/reloader/Dockerfile . <image:tag>
You'll need Docker 17.06.0-ce
or higher.
NatsCluster
type (code generation)
Updating the If you are adding a new field to the NatsCluster
, then you have to
get the deepcopy-gen
tools first.
$ go get -u github.com/kubernetes/gengo/examples/deepcopy-gen
Then run the code generation script in order to recreate
pkg/spec/zz_generated.deepcopy.go
with the required methods to
support that field filled in:
$ ./hack/codegen.sh
Running outside the cluster for debugging
For debugging purposes, it is also possible to run the operator outside of the cluster without having to build an image:
MY_POD_NAMESPACE=default MY_POD_NAME=nats-operator go run cmd/operator/main.go --debug-kube-config-path=$HOME/.kube/config
Direct access to the cluster
For debugging and development you might want to access the NATS cluster directly. For example, if you created the cluster with name example-nats-cluster
in namespace nats-io
you can forward ports of the pod with name example-nats-cluster-1
as follows:
$ kubectl port-forward -n nats-io example-nats-cluster-1 4222:4222