portainer: Duplicate resources with agent endpoint

Bug description

Sometimes (not always) the Containers page has duplicate entries for many containers. Not every container is duplicated. If I reload the page several times, the problem occurs for some page reloads only.

The links are also identical except for ?nodeName=... in the querystring. So Portainer thinks the same container (with the same task-id/slot) has been deployed to multiple nodes in the swarm.

When I click on one, I get the expected container detail page. When I click on another (with a different ?nodeName=... in the querystring, I get an error about being unable to retrieve the container.

Expected behavior One entry in the list per container.

Steps to reproduce the issue: Happens intermittently. When it happens, page refresh might or might not fix it. Even if it does, a few more reloads will show the problem again.

Technical details:

• Portainer version: agent-support
• Docker version (managed by Portainer): Docker for AWS 18.03.0-ce
• Platform (windows/linux): AWS/Linux
• Command used to start Portainer (docker run -p 9000:9000 portainer/portainer):

# Create networks for Docker services.
docker network create --driver overlay portainer-agent

# Create Portainer Agent service.
docker service create \
    --env AGENT_CLUSTER_ADDR='tasks.portainer-agent' \
    --limit-cpu 0.05 \
    --limit-memory 10M \
    --mode global \
    --mount type='bind',src='/var/run/docker.sock',dst='/var/run/docker.sock' \
    --name portainer-agent \
    --network portainer-agent \
    --reserve-cpu 0.01 \
    --reserve-memory 10M \
    portainer/agent:develop

# Create Portainer service.
docker service create \
    --env SERVICE_PORTS=9000 \
    --env VIRTUAL_HOST='https://portainer.*' \
    --limit-cpu 0.05 \
    --limit-memory 10M \
    --mount type='volume',volume-driver='cloudstor:aws',src='portainer-data',dst='/data'  \
    --name portainer \
    --network haproxy \
    --network portainer-agent \
    --reserve-cpu 0.01 \
    --reserve-memory 10M \
    portainer/portainer:agent-support -H 'tcp://tasks.portainer-agent:9001' --tlsskipverify

• Browser: Firefox