Installing Concourse 5.0 on Kubernetes using Helm

A close up of the helm of a boat

This article was written in conjunction with Éamon Ryan, Advisory Solutions Architect at Pivotal.

In early 2018, Pivotal and VMware came together to release Pivotal Container Service, known as PKS, to provide the power of Kubernetes with the reliability of BOSH and an alternative to Pivotal Application Service for software that needs it.

The rise of Kubernetes (k8s) as a popular developer platform led me to wonder how easy it would be to install Concourse 5.0 on PKS. It turns out, it’s very easy indeed. This tutorial will assume you’ve already installed PKS 1.3 on vSphere that has NSX-T, VMware’s software defined networking (SDN) solution, installed.

While these instructions are based on PKS, the Helm chart you will use work on any k8s provider. If you already have your cluster provisioned, you can skip ahead to “Using the Helm Chart to install Concourse”


Prerequisites

PKS uses the Pivotal On-Demand Services SDK to provide k8s clusters on demand (it’s not just a clever name!). The service broker that’s created when you install PKS needs to have plans, so that you can create clusters of different sizes and production worthiness. You can install Concourse on the default small plan that is provided, with one small change: because Concourse will be running containers inside containers, you must enable privileged containers. In the Ops Manager page for your specific plan, look toward the bottom of the page and you’ll see this checkbox.

Checkbox labelled “Enable Privileged Containers — Use with caution”

If that box is not checked, check it, and Apply Changes from the Ops Manager Installation Dashboard.

It should be noted that privileged containers can introduce security risks, and very few cases actually need it. In this case, Concourse does require privileged containers because it will be running containers (tasks and resources) inside containers (the worker pods).

Creating a Cluster for Concourse

The pks CLI, which works in conjunction with kubectl, is used to create clusters. From a command prompt, run the following commands to create a k8s cluster:

$ pks login -a api.pks.haas-433.pez.pivotal.io -u pksadmin
Password: *******************
API Endpoint: api.pks.haas-433.pez.pivotal.io
User: pksadmin
$ pks create-cluster concourse --plan small --external-hostname concourse-km.haas-433.pez.pivotal.io

Note: The DNS name does not need to exist when you create the cluster, but you must specify something. It is used to generate TLS certificates for your k8s cluster, so it must be something you can create a DNS entry for when the command succeeds.

Because pks is creating a new BOSH deployment under the covers, and running a number of errands under the covers, this can take up to 30 minutes to complete. You can track process by running the pks cluster command:

$ pks cluster concourse

Name: concourse
Plan Name: small
UUID: eaf1234f-d29c-4ad7-8103-ce0ae7777e11
Last Action: CREATE
Last Action State: succeeded
Last Action Description: Instance provisioning completed
Kubernetes Master Host: concourse-km.haas-433.pez.pivotal.io
Kubernetes Master Port: 8443
Worker Nodes: 3
Kubernetes Master IP(s): 10.197.59.136
Network Profile Name:

When you see Last Action State as succeeded, you can take the Kubernetes Master IP(s) listed and create a DNS A record to the Kubernetes Master Host domain listed.

Under the covers, the command has created a BOSH deployment that has created a Kubernetes Master VM, as well as the number of workers specified by your plan (the small plan creates 3 workers by default). It also created an NSX-T load balancer with multiple VIPs including the “Kubernetes Master IP” you were provided, so regardless of whether you had deployed a k8s cluster with 1 or 3 masters, you would only see one IP listed here, since it is actually the load balancer IP with the backend already populated with your real master IP addresses.

When you ask for PKS to create a k8s cluster, the following things occur:

  • A network (NSX-T T1 router and logical switch) is created for the master and workers to sit on
  • Networks are created for each default namespace (default, kube-system, kube-public, pks-system) for the pods in those namespaces with accompanying SNAT rules
  • Master and worker VMs are provisioned by BOSH
  • An NSX-T load balancer is created, consuming 2 routable VIPs and 3 Virtual Servers initially. The first VIP is used to load balancer the master VMs as stated above, and the second is explained below.
  • Various post-deploy errands are executed

Once your cluster is ready, back in kubectl land, it’s important to note the following two behaviors:

  1. If you create a service of type: LoadBalancer, NSX-T will automatically create a new L4 Virtual Server entry on the cluster load balancer with a new VIP.
  2. If you create a k8s Ingress, NSX-T will add an L7 HTTP forwarding rule to the second VIP that was pre-created on the cluster load balancer at deploy time.

Both methods allow you to access your workloads, it just depends on the method you want to use. The advantage here is you don’t have to setup/configure nginx or similar to perform these services as the NSX-T integration handles that for you.

Using the Cluster to install Concourse

Now that the cluster is created, we can (almost) go back to the kubectl and helm commands that you probably already know. You may be wondering how you authenticate against the cluster now, and that’s where the final pks command comes in:

$ pks get-credentials concourse

That command creates a $HOME/.kube/config that kubectl uses for authentication.

Now that you’re authenticated against the cluster, you need to create a couple of resources ahead of time.

Tiller

Helm is a client/server system with the helm CLI as the client, and a service called Tiller that runs in the cluster. To use Tiller in your cluster, you need to create a service account. Create a file on your machine called tiller-config.yml with the following contents:

apiVersion: v1
kind: ServiceAccount
metadata:
name: tiller
namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: tiller
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- kind: ServiceAccount
name: tiller
namespace: kube-system

And apply it to the cluster by running the command kubectl create -f tiller-config.yml. Once your service account is created, initialize it by running the command helm init --service-account tiller. Once this command completes successfully, your cluster will now be able to install helm charts.

It should be noted that because this is a very simple example, you used the default configuration for Tiller, which is less secure for a number of reasons, including the fact that it does not use TLS. For information around creating a more secure Tiller deployment, read the Helm Documentation.

Persistent Volumes

Concourse requires persistent volumes for both the workers (which run Concourse resources and tasks, not to be confused with k8s workers) and its database. Therefore, your cluster needs to have at least one StorageClass resource defined.

Because PKS is IaaS-agnostic, it does not automatically provision a StorageClass for you like most public clouds’ managed k8s offerings do. In vSphere, you can create both static and dynamic provisioned StorageClass resources, with dynamic being preferred in this case. As before, you’ll create a config yaml, but call this one storage-config.yml and make it look like this:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: concourse-storage-class
provisioner: kubernetes.io/vsphere-volume
parameters:
datastore: LUN01
diskformat: thin
fstype: ext3

The name concourse-storage-class above can be whatever you want. The datastore is the name of an actual Datastore object in your vSphere datacenter, where virtual disks can be created to be used as homes for your persistent volumes. Apply as before by running kubectl create -f storage-config.yml.

You’ve now created all of the prerequisite resources necessary to install Concourse!

Using the Helm Chart to install Concourse

A note for Pivotal customers: the Concourse Helm chart is not yet supported by Pivotal so please proceed with caution. However, there is a very active and vibrant community of operators who have deployed Concourse with the Helm chart and are very happy using it day-to-day

Now that you are ready to install Concourse, you can create the necessary values so that your installation is customized just for you. Helm charts live in a Github repository, so you can visit Concourse’s in the official repository here. In particular, you will want to grab the values.yaml file from that directory, as you will need to make customizations to it. That file is large and well-documented, so it will be easier to create a new yaml file with the necessary customizations — it will be merged with the default values.yaml at install time. Call this concourse-config.yml and make it look like this:

concourse:
web:
auth:
mainTeam:
localUser: admin
externalUrl: https://concourse.haas-433.pez.pivotal.io
bindPort: 80
tls:
enabled: true
bindPort: 443
worker:
baggageclaim:
driver: btrfs
persistence:
worker:
storageClass: concourse-storage-class
postgresql:
persistence:
storageClass: concourse-storage-class
web:
service:
type: LoadBalancer
secrets:
localUsers: SEE BELOW
webTlsCert: |
-----BEGIN CERTIFICATE-----
data data data data
-----END CERTIFICATE-----
webTlsKey: |
-----BEGIN RSA PRIVATE KEY-----
data data data data
-----END RSA PRIVATE KEY-----
workerKey: |
-----BEGIN RSA PRIVATE KEY-----
data data data data
-----END RSA PRIVATE KEY-----
workerKeyPub: ssh-rsa datadatadata comment

Let’s break down some of the big things here:

First, concourse.web.auth.mainTeam.localUser. Because this is a relatively simple example, we’ll create our main team with a local user. Make sure your user is also listed in secrets.localUsers, where the user is specified in the format username:password. Passwords can be plain text or bcrypt-hashed. Make sure your bcrypt hashing goes through at least 10 rounds. To do this on MacOS, use the following command:

htpasswd -bnBC 10 <USERNAME> <PASSWORD>

Next, concourse.web.externalUrl. It’s critical that you set this to a valid DNS name, because it’s used for callbacks. If you’re enabling TLS like in the example above, it must be an https:// URL. The DNS name need not be mapped to anything yet, because you won’t get the IP of the Load Balancer until after you install.

Setting concourse.worker.baggageclaim.driver to btrfs is a performance enhancement over the default naive driver, and Helm will warn you if you don’t change it.

I created a self-signed certificate for secrets.webTlsCert and secrets.webTlsKey, but you should probably use a signed certificate. The LoadBalancer resource created is Layer 4, and will pass traffic directly to the web pod, where it will terminate TLS.

You should also create your own worker SSH key, as it used to communicate between the worker pod and the web pod. There is a default value in the Helm chart, but that would, of course, be very insecure. Concourse 5.0 introduces a command called generate-key to generate this SSH key that you can use in place of ssh-keygen, if you desire.

$ mkdir $HOME/ssh-keys
$ docker run -v $HOME/ssh-keys:/keys -it concourse/concourse generate-key -t ssh -f /keys/worker

This command will create two files in $HOME/ssh-keys: worker and worker.pub. You can copy and paste the contents of the file into the secrets.workerKey and secrets.workerKeyPub fields.

Finally, you need to set the storage class name for PostgreSQL and the concourse workers to the name you created earlier so it can provision the necessary persistent volumes.

To install, run helm install --name concourse -f concourse-values.yml stable/concourse. The output will look something like this:

NAME:   concourse
LAST DEPLOYED: Wed Mar 20 11:39:17 2019
NAMESPACE: default
STATUS: DEPLOYED
RESOURCES:
==> v1/ConfigMap
NAME DATA AGE
concourse-postgresql 0 1s
==> v1/Namespace
NAME STATUS AGE
concourse-main Active 1s
==> v1/PersistentVolumeClaim
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
concourse-postgresql Pending concourse-storage-class 1s
==> v1/Pod(related)
NAME READY STATUS RESTARTS AGE
concourse-postgresql-6d6688747b-426th 0/1 Pending 0 1s
concourse-web-56798b6694-mz2rl 0/1 ContainerCreating 0 1s
concourse-worker-0 0/1 Init:0/1 0 1s
concourse-worker-1 0/1 Init:0/1 0 1s
==> v1/Secret
NAME TYPE DATA AGE
concourse-concourse Opaque 8 1s
concourse-postgresql Opaque 1 1s
==> v1/Service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
concourse-postgresql ClusterIP 10.100.200.32 <none> 5432/TCP 1s
concourse-web LoadBalancer 10.100.200.87 <pending> 80:32264/TCP,443:31098/TCP,2222:31294/TCP 1s
concourse-worker ClusterIP None <none> <none> 1s
==> v1/ServiceAccount
NAME SECRETS AGE
concourse-web 1 1s
concourse-worker 1 1s
==> v1beta1/ClusterRole
NAME AGE
concourse-web 1s
==> v1beta1/Deployment
NAME READY UP-TO-DATE AVAILABLE AGE
concourse-postgresql 0/1 1 0 1s
concourse-web 0/1 1 0 1s
==> v1beta1/PodDisruptionBudget
NAME MIN AVAILABLE MAX UNAVAILABLE ALLOWED DISRUPTIONS AGE
concourse-worker 1 N/A 0 1s
==> v1beta1/Role
NAME AGE
concourse-worker 1s
==> v1beta1/RoleBinding
NAME AGE
concourse-web-main 1s
concourse-worker 1s
==> v1beta1/StatefulSet
NAME READY AGE
concourse-worker 0/2 1s
NOTES:
* Concourse can be accessed:
* Within your cluster, at the following DNS name at port 80:
concourse-web.default.svc.cluster.local
* From outside the cluster, run these commands in the same shell:
NOTE: It may take a few minutes for the LoadBalancer IP to be available.
You can watch the status of by running 'kubectl get svc -w concourse-web'
export SERVICE_IP=$(kubectl get svc --namespace default concourse-web -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
echo http://$SERVICE_IP:80
* If this is your first time using Concourse, follow the tutorials at https://concourse-ci.org/tutorials.html

You can run helm status concourse to keep an eye on it. Eventually, the v1/Service block will look like this:

==> v1/Service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
concourse-postgresql ClusterIP 10.100.200.32 <none> 5432/TCP 27s
concourse-web LoadBalancer 10.100.200.87 10.197.59.143... 80:32264/TCP,443:31098/TCP,2222:31294/TCP 27s
concourse-worker ClusterIP None <none> <none> 27s

You can then take that EXTERNAL-IP and create a DNS A record from your hostname defined in concourse.web.externalUrl.

If you ever want to change any of the deployment values, including what auth mechanism you use for the main team, update your concourse-config.yml and run helm upgrade -f concourse-config.yml concourse stable/concourse and it will make your changes, except for secrets. See below on how to do that.

Changing Secrets

If you need to change your secrets — your certificate is expiring! you need to change your admin password — you can use standard kubectl commands to do this.

First, you need to edit the secret itself. To do this, run kubectl edit secret concourse-concourse. Note that in that name, the first concourse is the name of the release you specified in helm install. The second concourse is static. This will open in your editor of choice. Under the data: block, edit your values. You need to base-64 encode the value before putting it into the file, and do so only on one line. Once you save the file and close the editor, the secrets will be updated.

This is not enough, unfortunately, to trigger Concourse to pick up the new secrets. To do so, you need to edit the deployment. To do so, run kubectl edit deployment concourse-web --record, where concourse is your release name. It will also open in your editor. You need to change something under the spec block to trigger an update. I personally suggest adding a label under spec.template.metadata.labels. Mine looks like this:

spec:
progressDeadlineSeconds: 2147483647
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
app: concourse-web
release: concourse
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: concourse-web
last-updated: 2019-03-20T12.46.00 # My addition
release: concourse

When you save the file, because spec.strategy.type is set to RollingUpdate, it will trigger an update to the concourse-web deployment. You can watch the status of the update by running kubectl rollout status deployment concourse-web. Once it’s complete, you can verify that the change was made by running kubectl get pods. You will see a pod named concourse-web-xxxx-yyyy. It should have a lower age than your other concourse-* pods.

Conclusion

It may look like a lot of work went into this, but I began this process as an absolute Kubernetes neophyte, but with the help of Éamon, I went from an empty PKS cluster to a working Concourse in the span of about 2 hours, and at least half of that was spent with trial and error, fixing values and redeploying.

Happy Concourse-ing!