feat(cluster): Add support for request proxying for scale out (#2385)

* feat(cluster): initial commit for scale-out cluster

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

* feat(cluster): support shared storage scale out

This change introduces support for shared storage backed
zot cluster scale out.

New feature
Multiple stateless zot instances can run using the same shared
storage backend where each instance looks at a specific set
of repositories based on a siphash of the repository name to improve
scale as the load is distributed across multiple instances.
For a given config, there will only be one instance that can perform
dist-spec read/write on a given repository.

What's changed?
- introduced a transparent request proxy for dist-spec endpoints based on
siphash of repository name.
- new config for scale out cluster that specifies list of
cluster members.

Signed-off-by: Vishwas Rajashekar <vrajashe@cisco.com>

---------

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>
Signed-off-by: Vishwas Rajashekar <vrajashe@cisco.com>
Co-authored-by: Ramkumar Chinchani <rchincha@cisco.com>

.github/workflows/ecosystem-tools.yaml

@@ -27,7 +27,7 @@ jobs:
           go install github.com/swaggo/swag/cmd/swag@v1.16.2
           go mod download
           sudo apt-get update
-          sudo apt-get install libgpgme-dev libassuan-dev libbtrfs-dev libdevmapper-dev pkg-config rpm uidmap
+          sudo apt-get install libgpgme-dev libassuan-dev libbtrfs-dev libdevmapper-dev pkg-config rpm uidmap haproxy jq
           # install skopeo
           git clone -b v1.12.0 https://github.com/containers/skopeo.git
           cd skopeo
@@ -80,4 +80,37 @@ jobs:
         env:
           AWS_ACCESS_KEY_ID: fake
           AWS_SECRET_ACCESS_KEY: fake
+      - name: Run cloud scale-out tests
+        id: scale
+        run: |
+          make run-cloud-scale-out-tests
+        env:
+          AWS_ACCESS_KEY_ID: fake
+          AWS_SECRET_ACCESS_KEY: fake
+        continue-on-error: true
+      - name: print service logs for scale-out
+        run: |
+          find /tmp/zot-ft-logs -name '*.log' -print0 | xargs -0 cat
+      - name: multi-hop detection
+        id: multihop
+        run: |
+          if find /tmp/zot-ft-logs -name '*.log' -print0 | xargs -0 cat | grep 'cannot proxy an already proxied request'; then
+            echo "detected multi-hop"
+            exit 1
+          else
+            exit 0
+          fi
+        continue-on-error: true
+      - name: clean up scale-out logs
+        run: |
+          rm -r /tmp/zot-ft-logs
+      - name: fail job if error
+        if: ${{ steps.scale.outcome != 'success' || steps.multihop.outcome != 'success' }}
+        run: |
+          exit 1
+      - name: Upload zb test results zip as build artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: zb-cloud-scale-out-functional-results-${{ github.sha }}
+          path: ./zb-results/
       - uses: ./.github/actions/teardown-localstack