ananace/k8s-sidecar repository overview

⁠What?

This is a docker container intended to run inside a kubernetes cluster to collect config maps with a specified label and store the included files in an local folder. It can also send a html request to a specified URL after a configmap change. The main target is to be run as a sidecar container to supply an application with information from the cluster. The contained python script is working with the Kubernetes API 1.10

⁠Why?

Currently (April 2018) there is no simple way to hand files in configmaps to a service and keep them updated during runtime.

⁠How?

Run the container created by this repo together you application in an single pod with a shared volume. Specify which label should be monitored and where the files should be stored. By adding additional env variables the container can send a html request to specified URL.

⁠Features

• Extract files from config maps
• Filter based on label
• Update/Delete on change of configmap
• Concatenate into a single file

⁠Usage

Example for a simple deployment can be found in example.yaml. Depending on the cluster setup you have to grant yourself admin rights first: kubectl create clusterrolebinding cluster-admin-binding --clusterrole cluster-admin --user $(gcloud config get-value account)

⁠Configuration Environment Variables

• LABEL

  • description: Label that should be used for filtering.
  • required: true
  • type: string

• FOLDER

  • description: Folder where the files should be placed.
  • required: true
  • type: string

• CONCAT

  • description: File to concatenate result into.
  • required: false
  • type: string

• CONCAT_HEADER

  • description: Prepend source file as a header for each concat, prefixed with the given string. (a suitable comment character is recommended)
  • required: false
  • type: string

• NAMESPACE

  • description: If specified, the sidecar will search for config-maps inside this namespace. Otherwise the namespace in which the sidecar is running will be used. It's also possible to specify ALL to search in all namespaces.
  • required: false
  • type: string

• CONSIDERATE_UPDATE

  • description: When activated, the sidecar will agressively cache data to attempt to avoid causing unnecessary updates or requests.
  • default: true
  • required false
  • type: boolean

• TIMEOUT

  • description: If specified, the sidecar will time out and restart its watches after the given amount of seconds.
  • required false
  • type: integer

• REQ_URL

  • description: URL to which send a request after a configmap got reloaded.
  • required: false
  • type: URI

• REQ_METHOD

  • description: Request method GET(default) or POST.
  • required: false
  • type: string

• REQ_PAYLOAD

  • description: If you use POST you can also provide json payload.
  • required: false
  • type: json