open-nomad/command/agent/consul/catalog_testing.go
Seth Hoenig 0e44094d1a client: enable configuring enable_tag_override for services
Consul provides a feature of Service Definitions where the tags
associated with a service can be modified through the Catalog API,
overriding the value(s) configured in the agent's service configuration.

To enable this feature, the flag enable_tag_override must be configured
in the service definition.

Previously, Nomad did not allow configuring this flag, and thus the default
value of false was used. Now, it is configurable.

Because Nomad itself acts as a state machine around the the service definitions
of the tasks it manages, it's worth describing what happens when this feature
is enabled and why.

Consider the basic case where there is no Nomad, and your service is provided
to consul as a boring JSON file. The ultimate source of truth for the definition
of that service is the file, and is stored in the agent. Later, Consul performs
"anti-entropy" which synchronizes the Catalog (stored only the leaders). Then
with enable_tag_override=true, the tags field is available for "external"
modification through the Catalog API (rather than directly configuring the
service definition file, or using the Agent API). The important observation
is that if the service definition ever changes (i.e. the file is changed &
config reloaded OR the Agent API is used to modify the service), those
"external" tag values are thrown away, and the new service definition is
once again the source of truth.

In the Nomad case, Nomad itself is the source of truth over the Agent in
the same way the JSON file was the source of truth in the example above.
That means any time Nomad sets a new service definition, any externally
configured tags are going to be replaced. When does this happen? Only on
major lifecycle events, for example when a task is modified because of an
updated job spec from the 'nomad job run <existing>' command. Otherwise,
Nomad's periodic re-sync's with Consul will now no longer try to restore
the externally modified tag values (as long as enable_tag_override=true).

Fixes #2057
2020-02-10 08:00:55 -06:00

221 lines
5.2 KiB
Go

package consul
import (
"fmt"
"sync"
"github.com/hashicorp/consul/api"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/helper"
)
// MockCatalog can be used for testing where the CatalogAPI is needed.
type MockCatalog struct {
logger hclog.Logger
}
func NewMockCatalog(l hclog.Logger) *MockCatalog {
return &MockCatalog{logger: l.Named("mock_consul")}
}
func (m *MockCatalog) Datacenters() ([]string, error) {
dcs := []string{"dc1"}
m.logger.Trace("Datacenters()", "dcs", dcs, "error", "nil")
return dcs, nil
}
func (m *MockCatalog) Service(service, tag string, q *api.QueryOptions) ([]*api.CatalogService, *api.QueryMeta, error) {
m.logger.Trace("Services()", "service", service, "tag", tag, "query_options", q)
return nil, nil, nil
}
// MockAgent is a fake in-memory Consul backend for ServiceClient.
type MockAgent struct {
// maps of what services and checks have been registered
services map[string]*api.AgentServiceRegistration
checks map[string]*api.AgentCheckRegistration
// hits is the total number of times agent methods have been called
hits int
// mu guards above fields
mu sync.Mutex
// when UpdateTTL is called the check ID will have its counter inc'd
checkTTLs map[string]int
// What check status to return from Checks()
checkStatus string
}
// NewMockAgent that returns all checks as passing.
func NewMockAgent() *MockAgent {
return &MockAgent{
services: make(map[string]*api.AgentServiceRegistration),
checks: make(map[string]*api.AgentCheckRegistration),
checkTTLs: make(map[string]int),
checkStatus: api.HealthPassing,
}
}
// getHits returns how many Consul Agent API calls have been made.
func (c *MockAgent) getHits() int {
c.mu.Lock()
defer c.mu.Unlock()
return c.hits
}
// SetStatus that Checks() should return. Returns old status value.
func (c *MockAgent) SetStatus(s string) string {
c.mu.Lock()
old := c.checkStatus
c.checkStatus = s
c.mu.Unlock()
return old
}
func (c *MockAgent) Self() (map[string]map[string]interface{}, error) {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
s := map[string]map[string]interface{}{
"Member": {
"Addr": "127.0.0.1",
"DelegateCur": 4,
"DelegateMax": 5,
"DelegateMin": 2,
"Name": "rusty",
"Port": 8301,
"ProtocolCur": 2,
"ProtocolMax": 5,
"ProtocolMin": 1,
"Status": 1,
"Tags": map[string]interface{}{
"build": "0.8.1:'e9ca44d",
},
},
}
return s, nil
}
func (c *MockAgent) Services() (map[string]*api.AgentService, error) {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
r := make(map[string]*api.AgentService, len(c.services))
for k, v := range c.services {
r[k] = &api.AgentService{
ID: v.ID,
Service: v.Name,
Tags: make([]string, len(v.Tags)),
Meta: helper.CopyMapStringString(v.Meta),
Port: v.Port,
Address: v.Address,
EnableTagOverride: v.EnableTagOverride,
}
copy(r[k].Tags, v.Tags)
}
return r, nil
}
// Checks implements the Agent API Checks method.
func (c *MockAgent) Checks() (map[string]*api.AgentCheck, error) {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
r := make(map[string]*api.AgentCheck, len(c.checks))
for k, v := range c.checks {
r[k] = &api.AgentCheck{
CheckID: v.ID,
Name: v.Name,
Status: c.checkStatus,
Notes: v.Notes,
ServiceID: v.ServiceID,
ServiceName: c.services[v.ServiceID].Name,
}
}
return r, nil
}
// CheckRegs returns the raw AgentCheckRegistrations registered with this mock
// agent.
func (c *MockAgent) CheckRegs() []*api.AgentCheckRegistration {
c.mu.Lock()
defer c.mu.Unlock()
regs := make([]*api.AgentCheckRegistration, 0, len(c.checks))
for _, check := range c.checks {
regs = append(regs, check)
}
return regs
}
func (c *MockAgent) CheckRegister(check *api.AgentCheckRegistration) error {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
c.checks[check.ID] = check
// Be nice and make checks reachable-by-service
scheck := check.AgentServiceCheck
c.services[check.ServiceID].Checks = append(c.services[check.ServiceID].Checks, &scheck)
return nil
}
func (c *MockAgent) CheckDeregister(checkID string) error {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
delete(c.checks, checkID)
delete(c.checkTTLs, checkID)
return nil
}
func (c *MockAgent) ServiceRegister(service *api.AgentServiceRegistration) error {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
c.services[service.ID] = service
return nil
}
func (c *MockAgent) ServiceDeregister(serviceID string) error {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
delete(c.services, serviceID)
return nil
}
func (c *MockAgent) UpdateTTL(id string, output string, status string) error {
c.mu.Lock()
defer c.mu.Unlock()
c.hits++
check, ok := c.checks[id]
if !ok {
return fmt.Errorf("unknown check id: %q", id)
}
// Flip initial status to passing
check.Status = "passing"
c.checkTTLs[id]++
return nil
}
// a convenience method for looking up a registered service by name
func (c *MockAgent) lookupService(name string) []*api.AgentServiceRegistration {
c.mu.Lock()
defer c.mu.Unlock()
var services []*api.AgentServiceRegistration
for _, service := range c.services {
if service.Name == name {
services = append(services, service)
}
}
return services
}