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 # container-update-checker
+[![status-badge](https://woodpecker.narvas.tech/api/badges/vista/container-update-checker/status.svg)](https://woodpecker.narvas.tech/vista/container-update-checker)
 
 check if a container needs rebuilding  
-[![status-badge](https://woodpecker.narvas.tech/api/badges/vista/container-update-checker/status.svg)](https://woodpecker.narvas.tech/vista/container-update-checker)
+
+## Environment variables
+| Name            | Requered                        | Comment 
+|-----------------|---------------------------------|---------
+| BASE            | Yes                             | the image the Dockerfile is based on
+| TARGET          | Yes                             | the image thats based of `$BASE`
+| DOCKER_USERNAME | No<br>*used for private images* | the username for logging in into docker hub
+| DOCKER_PASSWORD | No<br>*used for private images* | the password for logging in into docker hub<br>(*you probaly want to use a token here*)
+
+## Exit codes
+
+| State                           | Exit code | Comment
+|---------------------------------|-----------|--------
+| BASE is more recent than TARGET | 0         | An update is needed
+| TARGET is more recent than BASE | 1         | No update is needed<br>(*the pipeline wil "fail" but that is wat we want* )
+| An error occured                | 0         | So the pipeline can continue
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