ci: login to Harbor before buildx

Jenkinsfile

@@ -37,6 +37,8 @@ spec:
           value: tcp://localhost:2375
         - name: DOCKER_TLS_CERTDIR
           value: ""
+        - name: DOCKER_CONFIG
+          value: /root/.docker
       volumeMounts:
         - name: workspace-volume
           mountPath: /home/jenkins/agent
@@ -138,6 +140,11 @@ PY
             apk add --no-cache bash git jq
             mkdir -p /root/.docker
             cp /docker-config/config.json /root/.docker/config.json
+            echo "Docker config: ${DOCKER_CONFIG:-unset} HOME=${HOME:-unset}"
+            REGISTRY_HOST="registry.bstein.dev"
+            USERNAME=$(jq -r ".auths[\\"${REGISTRY_HOST}\\"].username" /root/.docker/config.json)
+            PASSWORD=$(jq -r ".auths[\\"${REGISTRY_HOST}\\"].password" /root/.docker/config.json)
+            echo "${PASSWORD}" | docker login "${REGISTRY_HOST}" -u "${USERNAME}" --password-stdin
           '''
         }
       }