com.yahoo.vespa.hosted.provision.lb.LoadBalancer Maven / Gradle / Ivy

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Keeps track of node assignment in a multi-application setup.
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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.provision.lb;

import com.yahoo.config.provision.ClusterSpec;
import com.yahoo.vespa.applicationmodel.InfrastructureApplication;
import com.yahoo.vespa.hosted.provision.maintenance.LoadBalancerExpirer;

import java.time.Instant;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;

/**
 * Represents a load balancer for an application's cluster. This is immutable.
 *
 * @author mpolden
 */
public class LoadBalancer {

    private final LoadBalancerId id;
    private final String idSeed;
    private final Optional instance;
    private final State state;
    private final Instant changedAt;

    public LoadBalancer(LoadBalancerId id, String idSeed, Optional instance, State state, Instant changedAt) {
        this.id = Objects.requireNonNull(id, "id must be non-null");
        this.idSeed = Objects.requireNonNull(idSeed, "idSeed must be non-null");
        this.instance = Objects.requireNonNull(instance, "instance must be non-null");
        this.state = Objects.requireNonNull(state, "state must be non-null");
        this.changedAt = Objects.requireNonNull(changedAt, "changedAt must be non-null");
        if (state == State.active && instance.isEmpty()) {
            throw new IllegalArgumentException("Load balancer instance is required in state " + state);
        }
        if (id.application().equals(InfrastructureApplication.CONFIG_SERVER.id()) &&
            Set.of(State.inactive, State.removable).contains(state)) {
            throw new IllegalArgumentException("The config server load balancer is managed by Terraform - therefore the state cannot be '" + state + "'");
        }
    }

    /** An identifier for this load balancer. The ID is unique inside the zone */
    public LoadBalancerId id() {
        return id;
    }

    /** Seed to use for generating resource IDs for provisioned resources in this. */
    public String idSeed() {
        return idSeed;
    }

    /** The instance associated with this */
    public Optional instance() {
        return instance;
    }

    /** The current state of this */
    public State state() {
        return state;
    }

    /** Returns when this was last changed */
    public Instant changedAt() {
        return changedAt;
    }

    /** Returns a copy of this with state set to given state */
    public LoadBalancer with(State state, Instant changedAt) {
        if (changedAt.isBefore(this.changedAt)) {
            throw new IllegalArgumentException("Invalid changeAt: '" + changedAt + "' is before existing value '" +
                                               this.changedAt + "'");
        }
        if (this.state != State.reserved && state == State.reserved) {
            throw new IllegalArgumentException("Invalid state transition: " + this.state + " -> " + state);
        }
        return new LoadBalancer(id, idSeed, instance, state, changedAt);
    }

    /** Returns a copy of this with instance set to given instance */
    public LoadBalancer with(LoadBalancerInstance instance) {
        return new LoadBalancer(id, idSeed, Optional.of(instance), state, changedAt);
    }

    @Override
    public String toString() {
        return "LoadBalancer{" +
               "id=" + id +
               ", idSeed='" + idSeed + '\'' +
               ", instance=" + instance +
               ", state=" + state +
               ", changedAt=" + changedAt +
               '}';
    }

    /** Returns the effective container ID of given cluster. For combined clusters this returns the ID of the container cluster */
    public static ClusterSpec.Id containerId(ClusterSpec cluster) {
        return cluster.combinedId().orElse(cluster.id());
    }

    public enum State {

        /** The load balancer has been provisioned and reserved for an application */
        reserved,

        /**
         * The load balancer has been deactivated and is ready to be removed. Inactive load balancers are eventually
         * removed by {@link LoadBalancerExpirer}. Inactive load balancers may be reactivated if a deleted cluster is
         * redeployed.
         */
        inactive,

        /** The load balancer is in active use by an application */
        active,

        /** The load balancer should be removed immediately by {@link LoadBalancerExpirer} */
        removable,

    }

}