open-nomad/client/allocrunner/taskrunner/logmon_hook_test.go
Mahmood Ali 0b7085ba3a driver: allow disabling log collection
Operators commonly have docker logs aggregated using various tools and
don't need nomad to manage their docker logs.  Worse, Nomad uses a
somewhat heavy docker api call to collect them and it seems to cause
problems when a client runs hundreds of log collections.

Here we add a knob to disable log aggregation completely for nomad.
When log collection is disabled, we avoid running logmon and
docker_logger for the docker tasks in this implementation.

The downside here is once disabled, `nomad logs ...` commands and API
no longer return logs and operators must corrolate alloc-ids with their
aggregated log info.

This is meant as a stop gap measure.  Ideally, we'd follow up with at
least two changes:

First, we should optimize behavior when we can such that operators don't
need to disable docker log collection.  Potentially by reverting to
using pre-0.9 syslog aggregation in linux environments, though with
different trade-offs.

Second, when/if logs are disabled, nomad logs endpoints should lookup
docker logs api on demand.  This ensures that the cost of log collection
is paid sparingly.
2019-12-08 14:15:03 -05:00

108 lines
3.2 KiB
Go

package taskrunner
import (
"context"
"encoding/json"
"io/ioutil"
"net"
"os"
"testing"
plugin "github.com/hashicorp/go-plugin"
"github.com/hashicorp/nomad/client/allocrunner/interfaces"
"github.com/hashicorp/nomad/helper"
"github.com/hashicorp/nomad/helper/testlog"
"github.com/hashicorp/nomad/nomad/mock"
pstructs "github.com/hashicorp/nomad/plugins/shared/structs"
"github.com/stretchr/testify/require"
)
// Statically assert the logmon hook implements the expected interfaces
var _ interfaces.TaskPrestartHook = (*logmonHook)(nil)
var _ interfaces.TaskStopHook = (*logmonHook)(nil)
// TestTaskRunner_LogmonHook_LoadReattach unit tests loading logmon reattach
// config from persisted hook state.
func TestTaskRunner_LogmonHook_LoadReattach(t *testing.T) {
t.Parallel()
// No hook data should return nothing
cfg, err := reattachConfigFromHookData(nil)
require.Nil(t, cfg)
require.NoError(t, err)
// Hook data without the appropriate key should return nothing
cfg, err = reattachConfigFromHookData(map[string]string{"foo": "bar"})
require.Nil(t, cfg)
require.NoError(t, err)
// Create a realistic reattach config and roundtrip it
addr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:0")
require.NoError(t, err)
orig := &plugin.ReattachConfig{
Protocol: plugin.ProtocolGRPC,
Addr: addr,
Pid: 4,
}
origJSON, err := json.Marshal(pstructs.ReattachConfigFromGoPlugin(orig))
require.NoError(t, err)
cfg, err = reattachConfigFromHookData(map[string]string{
logmonReattachKey: string(origJSON),
})
require.NoError(t, err)
require.Equal(t, orig, cfg)
}
// TestTaskRunner_LogmonHook_StartStop asserts that a new logmon is created the
// first time Prestart is called, reattached to on subsequent restarts, and
// killed on Stop.
func TestTaskRunner_LogmonHook_StartStop(t *testing.T) {
t.Parallel()
alloc := mock.BatchAlloc()
task := alloc.Job.TaskGroups[0].Tasks[0]
dir, err := ioutil.TempDir("", "nomadtest")
require.NoError(t, err)
defer func() {
require.NoError(t, os.RemoveAll(dir))
}()
hookConf := newLogMonHookConfig(task.Name, dir)
runner := &TaskRunner{logmonHookConfig: hookConf}
hook := newLogMonHook(runner, testlog.HCLogger(t))
req := interfaces.TaskPrestartRequest{
Task: task,
}
resp := interfaces.TaskPrestartResponse{}
// First prestart should set reattach key but never be Done as it needs
// to rerun on agent restarts to reattach.
require.NoError(t, hook.Prestart(context.Background(), &req, &resp))
defer hook.Stop(context.Background(), nil, nil)
require.False(t, resp.Done)
origHookData := resp.State[logmonReattachKey]
require.NotEmpty(t, origHookData)
// Running prestart again should effectively noop as it reattaches to
// the running logmon.
req.PreviousState = map[string]string{
logmonReattachKey: origHookData,
}
require.NoError(t, hook.Prestart(context.Background(), &req, &resp))
require.False(t, resp.Done)
origHookData = resp.State[logmonReattachKey]
require.Equal(t, origHookData, req.PreviousState[logmonReattachKey])
// Running stop should shutdown logmon
stopReq := interfaces.TaskStopRequest{
ExistingState: helper.CopyMapStringString(resp.State),
}
require.NoError(t, hook.Stop(context.Background(), &stopReq, nil))
}