# Upstream Load Balancing

This article covers Pomerium built-in load balancing capabilities in presence of multiple upstreams.

# Multiple Upstreams

You may specify multiple servers for your upstream application, and Pomerium would load balance user requests between them.

policy:
  - from: https://myapp.localhost.pomerium.io
    to:
      - http://myapp-srv-1:8080
      - http://myapp-srv-2:8080

TIP

In the presence of multiple upstreams, make sure to specify either an active or passive health check, or both, to avoid requests being served to an unhealthy backend.

# Active Health Checks

Active health checks issue periodic requests to each upstream to determine its health. See Health Checking (opens new window) for a comprehensive overview.

# HTTP Example

policy:
  - from: https://myapp.localhost.pomerium.io
    to:
      - http://myapp-srv-1:8080
      - http://myapp-srv-2:8080
    health_checks:
      - timeout: 10s
        interval: 60s
        healthy_threshold: 1
        unhealthy_threshold: 2
        http_health_check:
          path: "/"

# TCP Example

policy:
  - from: tcp+https://tcp-service.localhost.pomerium.io
    to:
      - tcp://tcp-1.local
      - tcp://tcp-2.local
    health_checks:
      - timeout: 1s
        interval: 5s
        unhealthy_threshold: 3
        healthy_threshold: 1
        tcp_health_check:
          send:
            text: "50494E47" #PING
          receive:
            text: "504F4E47" #PONG

# Passive Health Checks

Passive health check tries to deduce upstream server health based on recent observed responses. See Outlier Detection (opens new window) for comprehensive overview.

policy:
  - from: https://myapp.localhost.pomerium.io
    to:
      - http://myapp-srv-1:8080
      - http://myapp-srv-2:8080
    outlier_detection: {}

# Load Balancing Method

lb_policy should be set to one of the values (opens new window):

# Example

policy:
  - from: https://myapp.localhost.pomerium.io
    to:
      - http://myapp-srv-1:8080
      - http://myapp-srv-2:8080
      - http://myapp-srv-3:8080
      - http://myapp-srv-4:8080
      - http://myapp-srv-5:8080
    lb_policy: LEAST_REQUEST
    least_request_lb_config:
      choice_count: 2 # current envoy default

# Load Balancing Weight

When a list of upstream URLs is specified in the to field, you may append an optional load balancing weight parameter. The individual lb_policy settings will take this weighting into account when making routing decisions.

# Example

This configuration uses the default round_robin load balancer policy but specifies different frequency of selection be applied to the upstreams.

policy:
  - from: https://myapp.localhost.pomerium.io
    to:
      - http://myapp-srv-1:8080,10
      - http://myapp-srv-2:8080,20
      - http://myapp-srv-3:8080,30
      - http://myapp-srv-4:8080,20
      - http://myapp-srv-5:8080,10

# Further reading

Last Updated: 6/1/2021, 3:35:38 AM



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