[TASK] Properly containerize backend component

[andyatmiami]

Description

Presently, attempting to run make docker-build in the workspaces/backend component results in the following:

$ gmake docker-build
docker build -t nbv2-backend:latest .
DEPRECATED: The legacy builder is deprecated and will be removed in a future release.
            Install the buildx component to build images with BuildKit:
            https://docs.docker.com/go/buildx/

Sending build context to Docker daemon  262.7kB
[1/2] STEP 1/12: FROM golang:1.22 AS builder
[1/2] STEP 2/12: ARG TARGETOS
--> Using cache 07e5d0adf0bc19d071694e9fa1f7104f2f635be94c70dfad1f4c456807986d8e
--> 07e5d0adf0bc
[1/2] STEP 3/12: ARG TARGETARCH
--> Using cache 8a19f25cfe94e0ee6691c78fb9a9b97975260c8d7d7af58f6437164b582abadd
--> 8a19f25cfe94
[1/2] STEP 4/12: WORKDIR /workspace
--> Using cache cf6fa1ec0ee33598cd258803a96d9c2a1dce1006e8a21150495838e8cc9bf46f
--> cf6fa1ec0ee3
[1/2] STEP 5/12: COPY go.mod go.sum ./
--> Using cache 58e7f699896bb9c388ece82b31b36c999d685e63df3049242736d5c3d47aec81
--> 58e7f699896b
[1/2] STEP 6/12: RUN go mod download
go: github.com/kubeflow/notebooks/workspaces/controller@v0.0.0 (replaced by ../controller): reading /controller/go.mod: open /controller/go.mod: no such file or directory
building at STEP "RUN go mod download": while running runtime: exit status 1

gmake: *** [Makefile:94: docker-build] Error 1

As the error indicates - this stems from the replace directive defined in go.mod

You can see the directive states:

replace github.com/kubeflow/notebooks/workspaces/controller => ../controller

HOWEVER - in the docker-build Makefile target - we are only passing the current directory as build context

• Please note a similar issue also exists in the docker-buildx Makefile target

As ../controller then isn't part of the build context - there is no way this will currently ever succeed.

Acceptance Criteria

• docker-build can produce a container image of the backend component
• docker-buildx can produce a container image of the backend component
• The resulting container image can be run with a container engine (podman / docker ) and be at parity with functionality available when running locally

[andyatmiami]

/area v2
/area backend

[liavweiss]

/assign