Combined with the Headless Service, this allows pods to have stable identification. The name of the pod is not random, instead each pod gets an ordinal name. Unlike Kubernetes ReplicaSets, pods created under a StatefulSet have a few unique attributes. StatefulSets differ from Kubernetes ReplicaSets (not to be confused with MongoDB replica sets!) in certain ways that makes them more suited for stateful applications. The StatefulSet actually runs MongoDB and orchestrates everything together. You can tell this is a Headless Service because the clusterIP is set to “None.” Other than that, it looks exactly the same as any normal Kubernetes Service. The configuration for the StorageClass looks like this:ĪpiVersion: v1 kind: Service metadata: name: mongo labels: name: mongo spec: ports: - port: 27017 targetPort: 27017 clusterIP: None selector: role: mongo #Old versions of mongodb for mac driversThere are currently drivers for AWS, Azure, Google Cloud, GlusterFS, OpenStack Cinder, vSphere, Ceph RBD, and Quobyte. On GCP, your storage choices are SSDs and hard disks. For example, if you run Kubernetes in your own datacenter, you can use GlusterFS. You can set up many different types of StorageClasses in a ton of different environments. The storage class tells Kubernetes what kind of storage to use for the database nodes. That's it! With these two commands, you have launched all the components required to run an highly available and redundant MongoDB replica set.Īt an high level, it looks something like this: To create the MongoDB replica set, run these two commands: kubectl apply -f googlecloud\_ssd.yaml I’ve created the configuration files for these already, and you can clone the example from GitHub: git clone Ĭd /mongo-k8s-sidecar/example/StatefulSet/ To set up the MongoDB replica set, you need three things: A StorageClass, a Headless Service, and a StatefulSet. Then, authenticate into the cluster: gcloud container clusters get-credentials test-cluster #Old versions of mongodb for mac freeFeel free to customize the command as you see fit. This will make a three node Kubernetes cluster. To create a Kubernetes 1.5 cluster, run the following command: gcloud container clusters create "test-cluster" Once you have a Google Cloud project created and have your Google Cloud SDK setup (hint: gcloud init), we can create our cluster. If you want to follow along with this tutorial and use Google Cloud Platform, you also need the Google Cloud SDK. The sidecar container used for auto-configuration is also unsupported.īefore we get started, you’ll need a Kubernetes 1.5 and the Kubernetes command line tool. Note: StatefulSets are currently a beta resource. You can create and manage your MongoDB replica set natively in Kubernetes, without the need for scripts and Makefiles. With StatefulSets, these headaches finally go away. Scaling the set up and down meant managing all of these resources manually, which is an opportunity for error, and would put your stateful application at risk In the previous example, we created a Makefile to ease the management of these resources, but it would have been great if Kubernetes could just take care of all of this for us. You had to manually create a disk, a ReplicationController, and a service for each replica. While the replica set in my previous blog post worked, there were some annoying steps that you needed to follow. #Old versions of mongodb for mac how toIf you’ve followed my previous posts, you know how to create a MEAN Stack app with Docker, then migrate it to Kubernetes to provide easier management and reliability, and create a MongoDB replica set to provide redundancy and high availability. With StatefulSets, Kubernetes makes it much easier to run stateful workloads such as databases. Kubernetes 1.5 includes the new StatefulSet API object (in previous versions, StatefulSet was known as PetSet). At Google, everything runs in a container, including databases. “Containers are stateless!” they say, and “databases are pointless without state!” #Old versions of mongodb for mac codeThe code examples need changes to work on a current Kubernetes cluster.Ĭonventional wisdom says you can’t run a database in a container.
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