ArgoCD: an overview, SSL configuration, and an application deploy

By | 11/22/2020
 

ArgoCD helps to deliver applications to Kubernetes by using the GitOps approach, i.e. when a Git-repository is used as a source of trust, thus all manifest, configs and other data are stored in a repository.

It can b used with Kubernetes manifest, kustomize, ksonnet, jsonnet, and what we are using in our project – Helm-charts.

ArgoCD spins up its controller in the cluster and watches for changes in a repository to compare it with resources deployed in the cluster, synchronizing their states.

Some additional features which are really useful are SSO with SAML, so we can integrate it with our Okta, it can deploy to multiple clusters, Kubernetes RBAC support, great WebUI and CLI, Github, GitLab, etc webhooks integration, plus Prometheus metrics out of the box, and awesome documentation.

I’m planning to us eArgoCD to replace our current deployment process with Jenkins and Helm, see the Helm: пошаговое создание чарта и деплоймента из Jenkins post (Rus).

Components

ArgoCD consists of the three main components – API server, Repository Server, and Application Controller.

  • API server (pod: argocd-server): controls the whole ArgoCD instance, all its operations, authentification, and secrets access which are stored as Kubernetes Secrets, etc
  • Repository Server (pod: argocd-repo-server): stores and synchronizes data from configured Git-repositories and generates Kubernetes manifests
  • Application Controller (pod: argocd-application-controller): used to monitor applications in a Kubernetes cluster to make them the same as they are described in a repository, and controls PreSync, Sync, PostSync hooks

ArgoCD CLI installation

In macOS:

brew install argocd

In Linux – from the Github repository:

VERSION=$(curl --silent "https://api.github.com/repos/argoproj/argo-cd/releases/latest" | grep '"tag_name"' | sed -E 's/.*"([^"]+)".*/\1/')
sudo curl -sSL -o /usr/local/bin/argocd https://github.com/argoproj/argo-cd/releases/download/$VERSION/argocd-linux-amd64
sudo chmod +x /usr/local/bin/argocd

Check it:

argocd version
argocd: v1.7.9+f6dc8c3
BuildDate: 2020-11-17T23:18:20Z
GitCommit: f6dc8c389a00d08254f66af78d0cae1fdecf7484
GitTreeState: clean
GoVersion: go1.14.12
Compiler: gc
Platform: linux/amd64

Running ArgoCD in Kubernetes

And let’s spin up an ArgoCD instance. We can use a manifest from the documentation which will create all necessary resources such as CRD, ServiceAccounts, RBAC roles and bindingConfigMaps, Secrets, Services, and Deployments.

I’m pretty sure there is an existing Helm chart for ArgoCD, but this time let’s use the manifest as it is described in the  Getting Started.

The documentation suggests to use the argocd namespace and it will be simpler, but we are not looking for simplicity so let’s create own namespace:

kubectl create namespace dev-1-devops-argocd-ns
namespace/dev-1-devops-argocd-ns created

Deploy resources:

kubectl apply -n dev-1-devops-argocd-ns -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Edit the argcd-server Service – change its type to the LoadBalancer to get access to the WebUI from the world:

kubectl -n dev-1-devops-argocd-ns patch svc argocd-server -p '{"spec": {"type": "LoadBalancer"}}'
service/argocd-server patched

Find its URL:

kubectl -n dev-1-devops-argocd-ns get svc argocd-server
NAME            TYPE           CLUSTER-IP      EXTERNAL-IP                                                              PORT(S)                      AGE
argocd-server   LoadBalancer   172.20.142.44   ada***585.us-east-2.elb.amazonaws.com   80:32397/TCP,443:31693/TCP   4m21s

A password for the ArgoCD is generated automatically is set to the name of its pod’s name, get it with the next command:

kubectl -n dev-1-devops-argocd-ns get pods -l app.kubernetes.io/name=argocd-server -o name | cut -d'/' -f 2
argocd-server-794857c8fb-xqgmv

Log in via CLI, don’t pay attention to the certificate error:

argocd login ada***585.us-east-2.elb.amazonaws.com
WARNING: server certificate had error: x509: certificate is valid for localhost, argocd-server, argocd-server.dev-1-devops-argocd-ns, argocd-server.dev-1-devops-argocd-ns.svc, argocd-server.dev-1-devops-argocd-ns.svc.cluster.local, not ada***585.us-east-2.elb.amazonaws.com. Proceed insecurely (y/n)? y
Username: admin
Password:
'admin' logged in successfully
Context 'ada***585.us-east-2.elb.amazonaws.com' updated

Change the password:

argocd account update-password
*** Enter current password:
*** Enter new password:
*** Confirm new password:
Password updated

Open WebUI, again ignore the SSL warning, we will set it up in a moment, and log in:

LoadBalancer, SSL, and DNS

Cool – we have all services running, now let’s configure a DNS name and an SSL certificate.

AWS ALB and ELB didn’t support gRPC, see AWS Application Load Balancers (ALBs) And Classic ELB (HTTP Mode), thus we can not use the ALB Ingress Controller here.

Let’s leave the Service with the LoadBalancer type as we did it above – it creates an AWS Classic LoadBalancer.

SSL certificate can be issued with the AWS Certificate Manager in the same region as our cluster and load balancer are created and save its ARN.

Download the manifest file:

wget https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Find the argocd-server Service:

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/component: server
    app.kubernetes.io/name: argocd-server
    app.kubernetes.io/part-of: argocd
  name: argocd-server
spec:
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 8080
  - name: https
    port: 443
    protocol: TCP
    targetPort: 8080
  selector:
    app.kubernetes.io/name: argocd-server

To the annotations add the service.beta.kubernetes.io/aws-load-balancer-ssl-cert, in the spec.type – the LoadBalancer type, and limit access with the  loadBalancerSourceRanges:

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/component: server
    app.kubernetes.io/name: argocd-server
    app.kubernetes.io/part-of: argocd
  name: argocd-server
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-ssl-cert: "arn:aws:acm:us-east-1:534***385:certificate/ddaf55b0-***-53d57c5ca706"
spec:
  type: LoadBalancer
  loadBalancerSourceRanges:
  - "31.***.***.117/32"
  - "194.***.***.24/29"
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 8080
  - name: https
    port: 443
    protocol: TCP
    targetPort: 8080
  selector:
    app.kubernetes.io/name: argocd-server

Deploy it:

kubectl -n dev-1-devops-argocd-ns apply -f install.yaml

Check the ELB’s SSL:

Create a DNS record:

Open the URL – and get the ERR_TOO_MANY_REDIRECTS error:

ArgoCD SSL: ERR_TOO_MANY_REDIRECTS

Go to the Google and find this topic – https://github.com/argoproj/argo-cd/issues/2953.

Go back to the install.yaml, in the Deployment argocd-server add the --insecure flag:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/component: server
    app.kubernetes.io/name: argocd-server
    app.kubernetes.io/part-of: argocd
  name: argocd-server
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name: argocd-server
  template:
    metadata:
      labels:
        app.kubernetes.io/name: argocd-server
    spec:
      containers:
      - command:
        - argocd-server
        - --staticassets
        - /shared/app
        - --insecure
...

Deploy it over, and check:

Okay – we are done here.

ArgoCD: deploy from a Github repository

And let’s proceed with the example from the Getting started guide – Helm deployment will be observed in the following part.

Click on the New App, specify a name, and set Project == default:

In the Git set the https://github.com/argoproj/argocd-example-apps.git URL  and a path inside of the repo – guestbook:

In the Destination – https://kubernetes.default.svc and the default namespace, click on the Create:

Looks like it was created, but why its Sync Status is Unknown?

Somethig went wrong:

argocd app get guestbook
Name:               guestbook
Project:            default
Server:             https://kubernetes.default.svc
Namespace:          default
...
CONDITION        MESSAGE                                                                                                                                                                                                                                                                    LAST TRANSITION
ComparisonError  failed to load initial state of resource PersistentVolumeClaim: persistentvolumeclaims is forbidden: User "system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller" cannot list resource "persistentvolumeclaims" in API group "" at the cluster scope  2020-11-19 15:35:51 +0200 EET
ComparisonError  failed to load initial state of resource PersistentVolumeClaim: persistentvolumeclaims is forbidden: User "system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller" cannot list resource "persistentvolumeclaims" in API group "" at the cluster scope  2020-11-19 15:35:51 +0200 EET

Try the synccommand from the CLI  – also didn’t work:

argocd app sync guestbook
Name:               guestbook
Project:            default
Server:             https://kubernetes.default.svc
Namespace:          default
...
Sync Status:        Unknown
Health Status:      Healthy
Operation:          Sync
Sync Revision:
Phase:              Error
Start:              2020-11-19 15:37:01 +0200 EET
Finished:           2020-11-19 15:37:01 +0200 EET
Duration:           0s
Message:            ComparisonError: failed to load initial state of resource Pod: pods is forbidden: User "system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller" cannot list resource "pods" in API group "" at the cluster scope;ComparisonError: failed to load initial state of resource Pod: pods is forbidden: User "system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller" cannot list resource "pods" in API group "" at the cluster scope
FATA[0001] Operation has completed with phase: Error

ArgocD: ComparisonError failed to load initial state of resource

Actually, better consider the “User “system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller” cannot list resource “pods” in API group “” at the cluster scope” error.

Check the argocd-application-controller ServiceAccount (really helpful here the Kubernetes: ServiceAccounts, JWT-tokens, authentication, and RBAC authorization post):

kubectl -n dev-1-devops-argocd-ns get serviceaccount argocd-application-controller
NAME                            SECRETS   AGE
argocd-application-controller   1         36m

Yup, we have the User system:serviceaccount:dev1-devops-argocd-ns:argocd-application-controller user created.

And it has the argocd-application-controller ClusterRoleBinding mapped:

kubectl -n dev-1-devops-argocd-ns get clusterrolebinding argocd-application-controller
NAME                            AGE
argocd-application-controller   24h

But it can’t perform the list pods action:

kubectl auth can-i list pods -n dev-1-devops-argocd-ns --as system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller
no

Although its ClusterRole gives all the permissions:

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    app.kubernetes.io/component: application-controller
    app.kubernetes.io/name: argocd-application-controller
    app.kubernetes.io/part-of: argocd
  name: argocd-application-controller
rules:
- apiGroups:
  - '*'
  resources:
  - '*'
  verbs:
  - '*'
- nonResourceURLs:
  - '*'
  verbs:
  - '*'

Check the ClusterRoleBinding again, but this time with the -o yaml output:

kubectl get clusterrolebinding argocd-application-controller -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
...
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: argocd-application-controller
subjects:
- kind: ServiceAccount
name: argocd-application-controller
namespace: argocd

namespace: argocd – aha, here we are.

Find two ClusterRoleBinding in the install.yamlargocd-application-controller and argocd-server, update their namespaces:

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    app.kubernetes.io/component: application-controller
    app.kubernetes.io/name: argocd-application-controller
    app.kubernetes.io/part-of: argocd
  name: argocd-application-controller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: argocd-application-controller
subjects:
- kind: ServiceAccount
  name: argocd-application-controller
  namespace: dev-1-devops-argocd-ns
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    app.kubernetes.io/component: server
    app.kubernetes.io/name: argocd-server
    app.kubernetes.io/part-of: argocd
  name: argocd-server
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: argocd-server
subjects:
- kind: ServiceAccount
  name: argocd-server
  namespace: dev-1-devops-argocd-ns

Well, that’s why I told about the default argocd namespace and why it’s simpler to use it, as if you are using a custom namespace then you’ll have to update those bindings.

So, fix it, deploy again:

kubectl auth can-i list pods -n dev-1-devops-argocd-ns --as system:serviceaccount:dev-1-devops-argocd-ns:argocd-application-controller
yes

Try to execute the sync one more time:

argocd app sync guestbook
TIMESTAMP  GROUP        KIND   NAMESPACE                  NAME    STATUS   HEALTH        HOOK  MESSAGE
2020-11-19T15:47:08+02:00            Service     default          guestbook-ui   Running   Synced              service/guestbook-ui unchanged
2020-11-19T15:47:08+02:00   apps  Deployment     default          guestbook-ui   Running   Synced              deployment.apps/guestbook-ui unchanged
Name:               guestbook
Project:            default
Server:             https://kubernetes.default.svc
...
Sync Status:        Synced to HEAD (6bed858)
Health Status:      Healthy
Operation:          Sync
Sync Revision:      6bed858de32a0e876ec49dad1a2e3c5840d3fb07
Phase:              Succeeded
Start:              2020-11-19 15:47:06 +0200 EET
Finished:           2020-11-19 15:47:08 +0200 EET
Duration:           2s
Message:            successfully synced (all tasks run)
GROUP  KIND        NAMESPACE  NAME          STATUS  HEALTH   HOOK  MESSAGE
Service     default    guestbook-ui  Synced  Healthy        service/guestbook-ui unchanged
apps   Deployment  default    guestbook-ui  Synced  Healthy        deployment.apps/guestbook-ui unchanged

And it’s working:

A pod’s logs:

The next step will be to deploy a Helm chart and figure out how to work with Helm Secrets.



Also published on Medium.