diff --git a/rfcs/0004-insecure-http/README.md b/rfcs/0004-insecure-http/README.md new file mode 100644 index 00000000..73bc2058 --- /dev/null +++ b/rfcs/0004-insecure-http/README.md @@ -0,0 +1,91 @@ +# RFC-0004 Block insecure HTTP connections across Flux + +**Status:** provisional + +**Creation Date:** 2022-09-08 + +## Summary +Flux should have a consistent way of disabling insecure HTTP connections. + +At the controller level, a flag should be present which would disable all outgoing HTTP connections. +At the object level, a field should be provided which would enable the use of non-TLS endpoints. + +If the use of a non-TLS endpoint is not supported, it should be made clear to users through the use of +logs and status conditions. + +## Motivation +Today the use of non-TLS based connections is inconsistent across Flux controllers. + +Controllers that deal only with `http` and `https` schemes have no way to block use of the `http` scheme at controller-level. +Some Flux objects provide a `.spec.insecure` field to enable the use of non-TLS based endpoints, but they don't clearly notify users when the option is not supported (e.g. Azure/GCP Buckets). + +### Goals +* Provide a flag across all Flux controllers which disables all outgoing HTTP connections. +* Add a field which enables the use of non-TLS endpoints to appropriate Flux objects. +* Provide a way for users to be made aware that their use of non-TLS endpoints is not supported if that is the case. + +### Non-Goals +* Break Flux's current behavior of allowing HTTP connections. + +## Proposal + +### Controllers +Flux users should be able to enforce that controllers are using HTTPS connections only. +This shall be enabled by adding a new boolean flag `--allow-insecure-http` to the following controllers: +* source-controller +* notification-controller +* image-automation-controller +* image-reflector-controller + +> Note: The flag shall not be added to the following controllers: +> * kustomize-controller: This flag is excluded from this controller, as the upstream `kubenetes-sigs/kustomize` project +> does not support disabling HTTP connections while fetching resources from remote bases. We can revisit this if the +> upstream project adds support for this at a later point in time. +> * helm-controller: This flag does not serve a purpose in this controller, as the controller does not make any HTTP calls. +> Furthermore although both controllers can also do remote applies, serving `kube-apiserver` over plain +> HTTP is disabled by default. While technically this can be enabled, the option for this configuration was also disabled +> quite a while back (ref: https://github.com/kubernetes/kubernetes/pull/65830/). + +The default value of this flag shall be `true`. This would ensure that there is no breaking change with controllers +still being able to access non-TLS endpoints. To disable this behavior and enforce the use of HTTPS connections, users would +have to explicitly pass the flag to the controller: + +```yaml +spec: + template: + spec: + containers: + - name: manager + image: fluxcd/source-controller + args: + - --watch-all-namespaces + - --log-level=info + - --log-encoding=json + - --enable-leader-election + - --storage-path=/data + - --storage-adv-addr=source-controller.$(RUNTIME_NAMESPACE).svc.cluster.local. + - --allow-insecure-http=false +``` + +### Objects +Some Flux objects, like `GitRepository`, provide a field for specifying a URL, and the URL would contain the scheme. +In such cases, the scheme can be used for inferring the transport type of the connection and consequently, +whether to use HTTP or HTTPS connections for that object. +But there are a few objects that don't allow such behavior, for example: + +* `ImageRepository`: It provides a field, `.spec.image`, which is used for specifying the URL of the image present on +a container registry. But any URL containing a scheme is considered invalid and HTTPS is the default transport used. +This prevents users from using images present on insecure registries. +* OCI `HelmRepository`: When using an OCI registry as a Helm repository, the `.spec.url` is expected to begin with `oci://`. +Since the scheme part of the URL is used to specify the type of `HelmRepository`, there is no way for users to specify +that the registry is hosted at a non-TLS endpoint. + +For such objects, we shall introduce a new boolean field `.spec.insecure`, which shall be `false` by default. Users that +need their object to point to an HTTP endpoint, can set this to `true`. + +### Precedence & Validity +Objects with `.spec.insecure` as `true ` will only be allowed if HTTP connections are allowed at the controller level. +Similarly, an object can have `.spec.insecure` as `true` only if the Saas/Cloud provider allows HTTP connections. +For example, using a `Bucket` with its `.spec.provider` set to `azure` would be invalid since Azure doesn't allow +HTTP connections. +