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 an HTTP 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.

Why?

This is our simple way to provide files from configmaps or secrets to a service and keep them updated during runtime.

How?

Run the container created by this repo together with your application in a 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 an HTTP request to specified URL.

Where?

Images are available at:

All are identical multi-arch images built for amd64, arm64, arm/v7, ppc64le and s390x

Features

Extract files from config maps and secrets
Filter based on label
Update/Delete on change of configmap or secret
Enforce unique filenames
CI tests for k8s v1.21-v1.28
Support binaryData for both Secret and ConfigMap kinds
- Binary data content is base64 decoded before generating the file on disk
- Values can also be base64 encoded URLs that download binary data e.g. executables
  - The key in the ConfigMap/Secret must end with ".url" (see)

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)

One can override the default directory that files are copied into using a configmap annotation defined by the environment variable FOLDER_ANNOTATION (if not present it will default to k8s-sidecar-target-directory). The sidecar will attempt to create directories defined by configmaps if they are not present. Example configmap annotation:

metadata:
  annotations:
    k8s-sidecar-target-directory: "/path/to/target/directory"

If the filename ends with .url suffix, the content will be processed as a URL which the target file contents will be downloaded from.

Configuration Environment Variables

name	description	required	default	type
`LABEL`	Label that should be used for filtering	true	-	string
`LABEL_VALUE`	The value for the label you want to filter your resources on. Don't set a value to filter by any value	false	-	string
`FOLDER`	Folder where the files should be placed	true	-	string
`FOLDER_ANNOTATION`	The annotation the sidecar will look for in configmaps to override the destination folder for files. The annotation value can be either an absolute or a relative path. Relative paths will be relative to `FOLDER`.	false	`k8s-sidecar-target-directory`	string
`NAMESPACE`	Comma separated list of namespaces. If specified, the sidecar will search for config-maps inside these namespaces. It's also possible to specify `ALL` to search in all namespaces.	false	namespace in which the sidecar is running	string
`RESOURCE`	Resource type, which is monitored by the sidecar. Options: `configmap`, `secret`, `both`	false	`configmap`	string
`METHOD`	If `METHOD` is set to `LIST`, the sidecar will just list config-maps/secrets and exit. With `SLEEP` it will list all config-maps/secrets, then sleep for `SLEEP_TIME` seconds. Anything else will continuously watch for changes (see https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes).	false	-	string
`SLEEP_TIME`	How many seconds to wait before updating config-maps/secrets when using `SLEEP` method.	false	`60`	integer
`REQ_URL`	URL to which send a request after a configmap/secret got reloaded	false	-	URI
`REQ_METHOD`	Request method `GET` or `POST` for requests tp `REQ_URL`	false	`GET`	string
`REQ_PAYLOAD`	If you use `REQ_METHOD=POST` you can also provide json payload	false	-	json
`REQ_RETRY_TOTAL`	Total number of retries to allow for any http request (`*.url` triggered requests, requests to `REQ_URI` and k8s api requests)	false	`5`	integer
`REQ_RETRY_CONNECT`	How many connection-related errors to retry on for any http request (`*.url` triggered requests, requests to `REQ_URI` and k8s api requests)	false	`10`	integer
`REQ_RETRY_READ`	How many times to retry on read errors for any http request (`.url` triggered requests, requests to `REQ_URI` and k8s api requests)	false	`5`	integer
`REQ_RETRY_BACKOFF_FACTOR`	A backoff factor to apply between attempts after the second try for any http request (`.url` triggered requests, requests to `REQ_URI` and k8s api requests)	false	`1.1`	float
`REQ_TIMEOUT`	How many seconds to wait for the server to send data before giving up for `.url` triggered requests or requests to `REQ_URI` (does not apply to k8s api requests)	false	`10`	float
`REQ_USERNAME`	Username to use for basic authentication for requests to `REQ_URL` and for `*.url` triggered requests	false	-	string
`REQ_PASSWORD`	Password to use for basic authentication for requests to `REQ_URL` and for `*.url` triggered requests	false	-	string
`REQ_BASIC_AUTH_ENCODING`	Which encoding to use for username and password as by default it's undefined (e.g. `utf-8`).	false	`latin1`	string
`SCRIPT`	Absolute path to a script to execute after a configmap got reloaded. It runs before calls to `REQ_URI`. If the file is not executable it will be passed to `sh`. Otherwise it's executed as is. Shebangs known to work are `#!/bin/sh` and `#!/usr/bin/env python`	false	-	string
`ERROR_THROTTLE_SLEEP`	How many seconds to wait before watching resources again when an error occurs	false	`5`	integer
`SKIP_TLS_VERIFY`	Set to `true` to skip tls verification for kube api calls	false	-	boolean
`REQ_SKIP_TLS_VERIFY`	Set to `true` to skip tls verification for all HTTP requests (except the Kube API server, which are controlled by `SKIP_TLS_VERIFY`).	false	-	boolean
`UNIQUE_FILENAMES`	Set to true to produce unique filenames where duplicate data keys exist between ConfigMaps and/or Secrets within the same or multiple Namespaces.	false	`false`	boolean
`DEFAULT_FILE_MODE`	The default file system permission for every file. Use three digits (e.g. '500', '440', ...)	false	-	string
`KUBECONFIG`	if this is given and points to a file or `~/.kube/config` is mounted k8s config will be loaded from this file, otherwise "incluster" k8s configuration is tried.	false	-	string
`ENABLE_5XX`	Set to `true` to enable pulling of 5XX response content from config map. Used in case if the filename ends with `.url` suffix (Please refer to the `*.url` feature here.)	false	-	boolean
`WATCH_SERVER_TIMEOUT`	polite request to the server, asking it to cleanly close watch connections after this amount of seconds (#85)	false	`60`	integer
`WATCH_CLIENT_TIMEOUT`	If you have a network outage dropping all packets with no RST/FIN, this is how many seconds your client waits on watches before realizing & dropping the connection. You can keep this number low. (#85)	false	`66`	integer
`IGNORE_ALREADY_PROCESSED`	Ignore already processed resource version. Avoid numerous checks on same unchanged resource. req kubernetes api >= v1.19	false	`false`	boolean
`LOG_LEVEL`	Set the logging level. (DEBUG, INFO, WARN, ERROR, CRITICAL)	false	`INFO`	string
`LOG_FORMAT`	Set a log format. (JSON or LOGFMT)	false	`JSON`	string
`LOG_TZ`	Set the log timezone. (LOCAL or UTC)	false	`LOCAL`	string
`LOG_CONFIG`	Log configuration file path. If not configured, uses the default log config for backward compatibility support. When not configured `LOG_LEVEL, LOG_FORMAT and LOG_TZ` would be used. Refer to Python logging for log configuration. For sample configuration file refer to file examples/example_logconfig.yaml	false	-	string