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. The contained Python script is working from Kubernetes API 1.10.
This is our simple way to provide files from configmaps or secrets to a service and keep them updated during runtime.
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.
Images are available at:
Both are identical multi-arch images built for amd64, arm64, arm/v7, ppc64le and s390x
- Extract files from config maps and secrets
- Filter based on label
- Update/Delete on change of configmap or secret
- Enforce unique filenames
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.
| 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 |
SCRIPT |
Absolute path to shell script to execute after a configmap got reloaded. It runs before calls to REQ_URI |
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 |
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 |