HiK8s daemons

This repository contains small background programs (daemons) that run in your cluster and provide data to HiK8s:

• rs/logd/README.md (log daemon)
• rs/watchd/README.md (watch daemon)

Local development

The code in this program is specific to Linux and requires a development container to be compiled on macOS. To do this, we create a Docker image and run a container from this image in which the relevant files are mounted as volumes:

1. Build the image

   IMAGE_NAME="hik8s/daemons-dev-container"
   docker build -t $IMAGE_NAME -f Dockerfile.dev .

2. Run a container

   IMAGE_NAME="hik8s/daemons-dev-container"
   WORKDIR=$(grep 'WORKDIR' Dockerfile.dev | awk '{print $2}') && echo $WORKDIR
   
   docker run -it \
   --volume "$(pwd)/rs:$WORKDIR/rs" \
   --volume "$(pwd)/Cargo.toml:$WORKDIR/Cargo.toml" \
   --volume "$(pwd)/.env:$WORKDIR/.env" \
   $IMAGE_NAME

3. Inside the container, run:

   cargo watch -x run

This runs logd and recompiles when you make changes in your IDE.

System diagram

The main components are log-daemon and watch-daemon. This is how they interact with your Kubernetes cluster:

graph TB
    subgraph "Kubernetes Cluster"
        subgraph "Node 2"
            LD1[logd]
            FS1[(Host Filesystem)]
            LD1 -->|reads 
            /var/log/pods/*| FS1
        end
        
        subgraph "Node 1"
            LD2[logd]
            FS2[(Host Filesystem)]
            LD2 -->|reads 
            /var/log/pods/*| FS2
        end

        subgraph "Control Plane"
            API[kube-apiserver]
            WD[watchd]
            WD -->|watches
            resources
            & CRs| API
        end
    end

    HK[api.hik8s.ai]
    LD1 -->|sends
    logs| HK
    LD2 -->|sends
    logs| HK
    WD -->|sends 
    events & 
    manifests| HK

    classDef daemon fill:#e1bee7,stroke:#8e24aa
    classDef api fill:#bbdefb,stroke:#1976d2
    classDef backend fill:#c8e6c9,stroke:#388e3c
    classDef storage fill:#fff3e0,stroke:#f57c00

    class LD1,LD2 daemon
    class API api
    class HK backend
    class FS1,FS2 storage

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CRs=custom resources, i.e. instances of CRDs