Controllers

The Controllers in this package leverage the controller-runtime package to define controllers that handle our custom resources (PodAccessRequest, PodAccessTemplate, ExecAccessRequest, ExecAccessTemplate). There are also controllers in this package that handle inbound webhooks via the Admission Controllers system.

Reconcilers

Our Reconciler controllers handle operating in a loop to ensure that our Custom Resources are consistently in the desired state. These controllers all implement a reconcile() function that is triggered by Watch... requests against the Kubernetes API.

Generally speaking, we try to keep the reconcile() functions short and easy to read/understand. The heavy lifting is actually done by our Builder structs.

ExecAccessTemplateReconciler

The ExecAccessTemplateReconciler is a very simple controller whose job is to make sure that the ExecAccessTemplate is valid and available for use. It primarily validates that the template has valid AccessConfig settings, and a valid TargetRef pointing to a real Pod controller (Deployment, etc).

sequenceDiagram
  participant Kubernetes
  participant Oz
  participant ExecAccessTemplateReconciler
  
  Note over Oz,Kubernetes: The Oz Controller begins to watch for resources
  Oz->>Kubernetes: Watch ExecAccessTemplate{} Resources...
  Kubernetes->>Oz: New ExecAccessTemplate{} Created
  
  loop Reconcile Loop...
    Note over Oz,ExecAccessTemplateReconciler: Runtime calls Reconciler function
    Oz->>ExecAccessTemplateReconciler: reconcile(...)
    
    Note over ExecAccessTemplateReconciler: Verify Target Reference Exists
    ExecAccessTemplateReconciler->>Kubernetes: Get Deployment{Name: foo}
    Kubernetes->>ExecAccessTemplateReconciler: 
    
    Note over ExecAccessTemplateReconciler: Verify Access Configurations Settings are Valid
    ExecAccessTemplateReconciler-->ExecAccessTemplateReconciler: api.VerifyMiscSettings()
    
    Note over ExecAccessTemplateReconciler: Write ready state back into resource
    ExecAccessTemplateReconciler->>Kubernetes: Update .Status.IsReady=True
  end

ExecAccessRequestReconciler

The ExecAccessRequestReconciler handles creating a Role and RoleBinding that grant an engineer kubectl exec ... access into an already existing Pod for a particular target deploymnt.

The reconciler logic itself is fairly simple, and most of the heavy lifting is actually handled by a ExecAccessBuilder.

sequenceDiagram
  participant Kubernetes
  participant Oz
  participant ExecAccessRequestReconciler
  participant ExecAccessBuilder
  participant ExecAccessTemplate

  Oz->>Kubernetes: Watch ExecAccessRequest{} Resources...
  Kubernetes->>Oz: New ExecAccessRequest{} Created

  loop Reconcile Loop...
    Note over Oz,ExecAccessRequestReconciler: Runtime calls Reconciler function
    Oz-->>ExecAccessRequestReconciler: reconcile(...)

    Note over ExecAccessRequestReconciler: Verify `ExecAccessTemplate` Exists
    ExecAccessRequestReconciler->>Kubernetes: Get ExecAccessTemplate{Name: foo}
    Kubernetes->>ExecAccessRequestReconciler: 

    Note over ExecAccessRequestReconciler: Verify AccessConfiguration Settings are Valid
    ExecAccessRequestReconciler-->>ExecAccessRequestReconciler: verifyDuration()
    ExecAccessRequestReconciler-->>ExecAccessRequestReconciler: isAccessExpired()

    Note over ExecAccessRequestReconciler,ExecAccessBuilder: Begin Building Access Resources
    ExecAccessRequestReconciler-->>ExecAccessBuilder: verifyAccessResourcesBuilt()

    ExecAccessBuilder->>Kubernetes: Get Deployment{Name: foo..}
    Kubernetes->>ExecAccessBuilder: 

    Note over ExecAccessBuilder: Create the Resources
    ExecAccessBuilder->>Kubernetes: Create Role{Name: foo...}
    ExecAccessBuilder->>Kubernetes: Create RoleBinding{Name: foo...}

    Note over ExecAccessRequestReconciler: Write ready state back into resource
    ExecAccessRequestReconciler->>Kubernetes: Update .Status.IsReady=True
  end

PodAccessTemplateReconciler

The PodAccessTemplateReconciler is a very simple controller whose job is to make sure that the PodAccessTemplate is valid and available for use. It primarily validates that the template has valid AccessConfig settings, and a valid TargetRef pointing to a real Pod controller (Deployment, etc).

sequenceDiagram
  participant Kubernetes
  participant Oz
  participant PodAccessTemplateReconciler
  
  Note over Oz,Kubernetes: The Oz Controller begins to watch for resources
  Oz->>Kubernetes: Watch PodAccessTemplate{} Resources...
  Kubernetes->>Oz: New PodAccessTemplate{} Created
  
  loop Reconcile Loop...
    Note over Oz,PodAccessTemplateReconciler: Runtime calls Reconciler function
    Oz->>PodAccessTemplateReconciler: reconcile(...)
    
    Note over PodAccessTemplateReconciler: Verify Target Reference Exists
    PodAccessTemplateReconciler->>Kubernetes: Get Deployment{Name: foo}
    Kubernetes->>PodAccessTemplateReconciler: 
    
    Note over PodAccessTemplateReconciler: Verify Access Configurations Settings are Valid
    PodAccessTemplateReconciler-->PodAccessTemplateReconciler: api.VerifyMiscSettings()
    
    Note over PodAccessTemplateReconciler: Write ready state back into resource
    PodAccessTemplateReconciler->>Kubernetes: Update .Status.IsReady=True
  end

PodAccessRequestReconciler

The PodAccessRequestReconciler handles the creation of a dedicated workload Pod for an engineer on-demand based on the configuration of a PodAccessTemplate. The reconciler logic itself is fairly simple, and most of the heavy lifting is actually handled by a PodAccessBuilder.

sequenceDiagram
  participant Kubernetes
  participant Oz
  participant PodAccessRequestReconciler
  participant PodAccessBuilder
  participant PodAccessTemplate
  
  Oz->>Kubernetes: Watch PodAccessRequest{} Resources...
  Kubernetes->>Oz: New PodAccessRequest{} Created

  loop Reconcile Loop...
    Note over Oz,PodAccessRequestReconciler: Runtime calls Reconciler function
    Oz-->>PodAccessRequestReconciler: reconcile(...)
    
    Note over PodAccessRequestReconciler: Verify `PodAccessTemplate` Exists
    PodAccessRequestReconciler->>Kubernetes: Get PodAccessTemplate{Name: foo}
    Kubernetes->>PodAccessRequestReconciler: 
    
    Note over PodAccessRequestReconciler: Verify AccessConfiguration Settings are Valid
    PodAccessRequestReconciler-->>PodAccessRequestReconciler: verifyDuration()
    PodAccessRequestReconciler-->>PodAccessRequestReconciler: isAccessExpired()
    
    Note over PodAccessRequestReconciler,PodAccessBuilder: Begin Building Access Resources
    PodAccessRequestReconciler-->>PodAccessBuilder: verifyAccessResourcesBuilt()
    
    PodAccessBuilder->>Kubernetes: Get Deployment{Name: foo..}
    Kubernetes->>PodAccessBuilder: 
    PodAccessBuilder-->>PodAccessTemplate: GenerateMutatedPodSpec(Deployment{}...)

    Note over PodAccessBuilder: Create the Resources
    PodAccessBuilder->>Kubernetes: Create Pod{Name: foo...}
    PodAccessBuilder->>Kubernetes: Create Role{Name: foo...}
    PodAccessBuilder->>Kubernetes: Create RoleBinding{Name: foo...}
    

    Note over PodAccessBuilder: Verify Resources Ready
    PodAccessRequestReconciler-->>PodAccessBuilder: verifyAccessResourcesReady()
    
    PodAccessBuilder->>Kubernetes: Get Pod{}.Status.Ready
    Kubernetes->>PodAccessBuilder: Pod{}.Status.Ready=True
    PodAccessBuilder-->>PodAccessRequestReconciler: Pod Is Ready

    Note over PodAccessRequestReconciler: Write ready state back into resource
    PodAccessRequestReconciler->>Kubernetes: Update .Status.IsReady=True
  end