open-nomad/scheduler/system_util.go

349 lines
11 KiB
Go

package scheduler
// The structs and helpers in this file are split out of scheduler_system.go and
// shared by the system and sysbatch scheduler. No code in the generic scheduler
// or reconciler should use anything here! If you need something here for
// service/batch jobs, double-check it's safe to use for all scheduler types
// before moving it into util.go
import (
"fmt"
"time"
"github.com/hashicorp/nomad/nomad/structs"
)
// materializeSystemTaskGroups is used to materialize all the task groups
// a system or sysbatch job requires.
func materializeSystemTaskGroups(job *structs.Job) map[string]*structs.TaskGroup {
out := make(map[string]*structs.TaskGroup)
if job.Stopped() {
return out
}
for _, tg := range job.TaskGroups {
for i := 0; i < tg.Count; i++ {
name := fmt.Sprintf("%s.%s[%d]", job.Name, tg.Name, i)
out[name] = tg
}
}
return out
}
// diffSystemAllocsForNode is used to do a set difference between the target allocations
// and the existing allocations for a particular node. This returns 8 sets of results,
// the list of named task groups that need to be placed (no existing allocation), the
// allocations that need to be updated (job definition is newer), allocs that
// need to be migrated (node is draining), the allocs that need to be evicted
// (no longer required), those that should be ignored, those that are lost
// that need to be replaced (running on a lost node), those that are running on
// a disconnected node but may resume, and those that may still be running on
// a node that has resumed reconnected.
func diffSystemAllocsForNode(
job *structs.Job, // job whose allocs are going to be diff-ed
nodeID string,
eligibleNodes map[string]*structs.Node,
notReadyNodes map[string]struct{}, // nodes that are not ready, e.g. draining
taintedNodes map[string]*structs.Node, // nodes which are down (by node id)
required map[string]*structs.TaskGroup, // set of allocations that must exist
allocs []*structs.Allocation, // non-terminal allocations that exist
terminal structs.TerminalByNodeByName, // latest terminal allocations (by node, id)
serverSupportsDisconnectedClients bool, // flag indicating whether to apply disconnected client logic
) *diffResult {
result := new(diffResult)
// Scan the existing updates
existing := make(map[string]struct{}) // set of alloc names
for _, exist := range allocs {
// Index the existing node
name := exist.Name
existing[name] = struct{}{}
// Check for the definition in the required set
tg, ok := required[name]
// If not required, we stop the alloc
if !ok {
result.stop = append(result.stop, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
supportsDisconnectedClients := exist.SupportsDisconnectedClients(serverSupportsDisconnectedClients)
reconnect := false
expired := false
// Only compute reconnect for unknown and running since they need to go
// through the reconnect process.
if supportsDisconnectedClients &&
(exist.ClientStatus == structs.AllocClientStatusUnknown ||
exist.ClientStatus == structs.AllocClientStatusRunning) {
reconnect = exist.NeedsToReconnect()
if reconnect {
expired = exist.Expired(time.Now())
}
}
// If we have been marked for migration and aren't terminal, migrate
if !exist.TerminalStatus() && exist.DesiredTransition.ShouldMigrate() {
result.migrate = append(result.migrate, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
// If we are a sysbatch job and terminal, ignore (or stop?) the alloc
if job.Type == structs.JobTypeSysBatch && exist.TerminalStatus() {
result.ignore = append(result.ignore, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
// Expired unknown allocs are lost. Expired checks that status is unknown.
if supportsDisconnectedClients && expired {
result.lost = append(result.lost, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
// Ignore unknown allocs that we want to reconnect eventually.
if supportsDisconnectedClients &&
exist.ClientStatus == structs.AllocClientStatusUnknown &&
exist.DesiredStatus == structs.AllocDesiredStatusRun {
result.ignore = append(result.ignore, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
node, nodeIsTainted := taintedNodes[exist.NodeID]
// Filter allocs on a node that is now re-connected to reconnecting.
if supportsDisconnectedClients &&
!nodeIsTainted &&
reconnect {
// Record the new ClientStatus to indicate to future evals that the
// alloc has already reconnected.
reconnecting := exist.Copy()
reconnecting.AppendState(structs.AllocStateFieldClientStatus, exist.ClientStatus)
result.reconnecting = append(result.reconnecting, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: reconnecting,
})
continue
}
// If we are on a tainted node, we must migrate if we are a service or
// if the batch allocation did not finish
if nodeIsTainted {
// If the job is batch and finished successfully, the fact that the
// node is tainted does not mean it should be migrated or marked as
// lost as the work was already successfully finished. However for
// service/system jobs, tasks should never complete. The check of
// batch type, defends against client bugs.
if exist.Job.Type == structs.JobTypeSysBatch && exist.RanSuccessfully() {
goto IGNORE
}
// Filter running allocs on a node that is disconnected to be marked as unknown.
if node != nil &&
supportsDisconnectedClients &&
node.Status == structs.NodeStatusDisconnected &&
exist.ClientStatus == structs.AllocClientStatusRunning {
disconnect := exist.Copy()
disconnect.ClientStatus = structs.AllocClientStatusUnknown
disconnect.AppendState(structs.AllocStateFieldClientStatus, structs.AllocClientStatusUnknown)
disconnect.ClientDescription = allocUnknown
result.disconnecting = append(result.disconnecting, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: disconnect,
})
continue
}
if !exist.TerminalStatus() && (node == nil || node.TerminalStatus()) {
result.lost = append(result.lost, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
} else {
goto IGNORE
}
continue
}
// For an existing allocation, if the nodeID is no longer
// eligible, the diff should be ignored
if _, ineligible := notReadyNodes[nodeID]; ineligible {
goto IGNORE
}
// Existing allocations on nodes that are no longer targeted
// should be stopped
if _, eligible := eligibleNodes[nodeID]; !eligible {
result.stop = append(result.stop, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
// If the definition is updated we need to update
if job.JobModifyIndex != exist.Job.JobModifyIndex {
result.update = append(result.update, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
continue
}
// Everything is up-to-date
IGNORE:
result.ignore = append(result.ignore, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: exist,
})
}
// Scan the required groups
for name, tg := range required {
// Check for an existing allocation
if _, ok := existing[name]; !ok {
// Check for a terminal sysbatch allocation, which should be not placed
// again unless the job has been updated.
if job.Type == structs.JobTypeSysBatch {
if alloc, termExists := terminal.Get(nodeID, name); termExists {
// the alloc is terminal, but now the job has been updated
if job.JobModifyIndex != alloc.Job.JobModifyIndex {
result.update = append(result.update, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: alloc,
})
} else {
// alloc is terminal and job unchanged, leave it alone
result.ignore = append(result.ignore, allocTuple{
Name: name,
TaskGroup: tg,
Alloc: alloc,
})
}
continue
}
}
// Require a placement if no existing allocation. If there
// is an existing allocation, we would have checked for a potential
// update or ignore above. Ignore placements for tainted or
// ineligible nodes
// Tainted and ineligible nodes for a non existing alloc
// should be filtered out and not count towards ignore or place
if _, tainted := taintedNodes[nodeID]; tainted {
continue
}
if _, eligible := eligibleNodes[nodeID]; !eligible {
continue
}
termOnNode, _ := terminal.Get(nodeID, name)
allocTuple := allocTuple{
Name: name,
TaskGroup: tg,
Alloc: termOnNode,
}
// If the new allocation isn't annotated with a previous allocation
// or if the previous allocation isn't from the same node then we
// annotate the allocTuple with a new Allocation
if allocTuple.Alloc == nil || allocTuple.Alloc.NodeID != nodeID {
allocTuple.Alloc = &structs.Allocation{NodeID: nodeID}
}
result.place = append(result.place, allocTuple)
}
}
return result
}
// diffSystemAllocs is like diffSystemAllocsForNode however, the allocations in the
// diffResult contain the specific nodeID they should be allocated on.
func diffSystemAllocs(
job *structs.Job, // jobs whose allocations are going to be diff-ed
readyNodes []*structs.Node, // list of nodes in the ready state
notReadyNodes map[string]struct{}, // list of nodes in DC but not ready, e.g. draining
taintedNodes map[string]*structs.Node, // nodes which are down or drain mode (by node id)
allocs []*structs.Allocation, // non-terminal allocations
terminal structs.TerminalByNodeByName, // latest terminal allocations (by node id)
serverSupportsDisconnectedClients bool, // flag indicating whether to apply disconnected client logic
) *diffResult {
// Build a mapping of nodes to all their allocs.
nodeAllocs := make(map[string][]*structs.Allocation, len(allocs))
for _, alloc := range allocs {
nodeAllocs[alloc.NodeID] = append(nodeAllocs[alloc.NodeID], alloc)
}
eligibleNodes := make(map[string]*structs.Node)
for _, node := range readyNodes {
if _, ok := nodeAllocs[node.ID]; !ok {
nodeAllocs[node.ID] = nil
}
eligibleNodes[node.ID] = node
}
// Create the required task groups.
required := materializeSystemTaskGroups(job)
result := new(diffResult)
for nodeID, allocs := range nodeAllocs {
diff := diffSystemAllocsForNode(job, nodeID, eligibleNodes, notReadyNodes, taintedNodes, required, allocs, terminal, serverSupportsDisconnectedClients)
result.Append(diff)
}
return result
}
// evictAndPlace is used to mark allocations for evicts and add them to the
// placement queue. evictAndPlace modifies both the diffResult and the
// limit. It returns true if the limit has been reached.
func evictAndPlace(ctx Context, diff *diffResult, allocs []allocTuple, desc string, limit *int) bool {
n := len(allocs)
for i := 0; i < n && i < *limit; i++ {
a := allocs[i]
ctx.Plan().AppendStoppedAlloc(a.Alloc, desc, "", "")
diff.place = append(diff.place, a)
}
if n <= *limit {
*limit -= n
return false
}
*limit = 0
return true
}