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hang the runner, agent=new sheriff (#270)

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* fix docker build

this is trivially incorrect since glide doesn't actually provide reproducible
builds. the idea is to build with the deps that we have checked into git, so
that we actually know what code is executing so that we might debug it...

all for multi stage build instead of what we had, but adding the glide step is
wrong. i added a loud warning so as to discourage this behavior in the future.

* hang the runner, agent=new sheriff

tl;dr agent is now runner, with a hopefully saner api

the general idea is get rid of all the various 'task' structs now, change our
terminology to only be 'calls' now, push a lot of the http construction of a
call into the agent, allow calls to mutate their state around their execution
easily and to simplify the number of code paths, channels and context timeouts
in something [hopefully] easy to understand.

this introduces the idea of 'slots' which are either hot or cold and are
separate from reserving memory (memory is denominated in 'tokens' now).
a 'slot' is essentially a container that is ready for execution of a call, be
it hot or cold (it just means different things based on hotness). taking a
look into Submit should make these relatively easy to grok.

sorry, things were pretty broken especially wrt timings. I tried to keep good
notes (maybe too good), to highlight stuff so that we don't make the same
mistakes again (history repeating itself blah blah quote). even now, there is
lots of work to do :)

I encourage just reading the agent.go code, Submit is really simple and
there's a description of how the whole thing works at the head of the file
(after TODOs). call.go contains code for constructing calls, as well as Start
/ End (small atm). I did some amount of code massaging to try to make things
simple / straightforward / fit reasonable mental model, but as always am open
to critique (the more negative the better) as I'm just one guy and wth do i
know...

-----------------------------------------------------------------------------

below enumerates a number of changes as briefly as possible (heh..):

models.Call all the things

removes models.Task as models.Call is now what it previously was.
models.FnCall is now rid of in favor of models.Call, despite the datastore
only storing a few fields of it [for now]. we should probably store entire
calls in the db, since app & route configurations can change at any given
moment, it would be nice to see the parameters of each call (costs db space,
obviously).

this removes the endpoints for getting & deleting messages, we were just
looping back to localhost to call the MQ (wtf? this was for iron integration i
think) and just calls the MQ.

changes the name of the FnLog to LogStore, confusing cause there's also a
`FuncLogger` which uses the Logstore (punting). removes other `Fn` prefixed
structs (redundant naming convention).

removes some unused and/or weird structs (IDStatus, CompleteTime)

updates the swagger

makes the db methods consistent to use 'Call' nomenclature.

remove runner nuisances:

* push down registry stuff to docker driver
* remove Environment / Stats stuff of yore
* remove unused writers (now in FuncLogger)
* remove 2 of the task types, old hot stuff, runner, etc

fixes ram available calculation on startup to not always be 300GB (helps a lot
on a laptop!)

format for DOCKER_AUTH env now is not a list but a map (there are no docs,
would prefer to get rid of this altogether anyway). the ~/.docker/cfg expected
format is unchanged.

removes arbitrary task queue, if a machine is out of ram we can probably just
time out without queueing... (can open separate discussion) in any case the
old one didn't really account well for hot tasks, it just lined everyone up in
the task queue if there wasn't a place to run hot and then timed them out
[even if a slot became free].

removes HEADER_ prefixing on any headers in the request to a invoke a call.
(this was inconsistent with cli for test anyway)

removes TASK_ID header sent in to hot only (this is a dupe of FN_CALL_ID,
which has not been removed)

now user functions can reply directly to the client. this means that for
cold containers if they write to stdout it will send a 200 + headers. for
hot containers, the user can reply directly to the client from the container,
i.e. with its preferred status code / headers (vs. always getting a 200).
the dispatch itself is a little http specific atm, i think we can add an
interchange format but the current version is easily extended to add json for
now, separate discussion. this eliminates a lot of the request/response
rewriting and buffering we were doing (yey). now Dispatch ONLY does input and
output, vs. managing the call timeout and having access to a call's fields.

cache is pushed down into agent now instead of in the front end, would like to
push it down to the datastore actually but it's here for now anyway. cache
delete functions removed (b/c fn is distributed anyway?). added app caching,
should help with latency.

in general, a lot of server/runner.go got pushed down into the agent. i think
it will be useful in testing to be able to construct calls without having to
invoke http handlers + async also needs to construct calls without a handler.

safe shutdown actually works now for everything (leaked / didn't wait on
certain things before)

now we're waiting for hot slots to open up while we're attempting to get ram
to launch a container if we didn't find any hot slots to run the call in
immediately. we can change this policy really easily now (no more channel
jungle; still some channels). also looking for somewhere else to go while the
container is launching now. slots now get sent _out_ of a container, vs.
a container receiving calls, which makes this kind of policy easier to
implement. this fixes a number of bugs around things like trying to execute
calls against containers that have not and may never start and trying to
launch a bazillion containers when there are no free containers. the driver api
underwent some changes to make this possible (relatively minimal, added Wait).
the easiest way to think about this is that allocating ram has moved 'up'
instead of just wrapping launching containers, so that we can select on a
channel trying to find ram.

not dispatching hot calls to containers that died anymore either...

the timeout is now started at the beginning of Submit, rather than Dispatch or
the container itself having to manage the call timeout, which was an
inaccurate way of doing things since finding a slot / allocating ram / pulling
image can all take a non-trivial (timeout amount, even!) amount of time. this
makes for much more reasonable response times from fn under load, there's
still a little TODO about handling cold+timeout container removal response
times but it's much improved.

if call.Start is called with < call.timeout/2 time left, then the call will
not be executed and return a timeout. we can discuss. this makes async play
_a lot_ nicer, specifically. for large timeouts / 2 makes less sense.

env is no longer getting upper cased (admittedly, this can look a little weird
now). our whole route.Config/app.Config/env/headers stuff probably deserves a
whole discussion...

sync output no longer has the call id in json if there's an error / timeout.
we could add this back to signify that it's _us_ writing these but this was
out of place. FN_CALL_ID is still shipped out to get the id for sync calls,
and async [server] output remains unchanged.

async logs are now an entire raw http request (so that a user can write a 400
or something from their hot async container)

async hot now 'just works'

cold sync calls can now reply to the client before container removal, which
shaves a lot of latency off of those (still eat start). still need to figure
out async removal if timeout or something.

-----------------------------------------------------------------------------

i've located a number of bugs that were generally inherited, and also added
a number of TODOs in the head of the agent.go file according to robustness we
probably need to add. this is at least at parity with the previous
implementation, to my knowledge (hopefully/likely a good bit ahead). I can
memorialize these to github quickly enough, not that anybody searches before
adding bugs anyway (sigh).

the big thing to work on next imo is async being a lot more robust,
specifically to survive fn server failures / network issues.

thanks for review (gulp)
This commit is contained in:
Reed Allman
2017-09-05 10:32:51 -07:00
committed by Denis Makogon
parent 1b1b64436f
commit 71a88a991c
100 changed files with 2151 additions and 4121 deletions
Download Patch File Download Diff File Expand all files Collapse all files

269
api/agent/drivers/driver.go Normal file
View File

@@ -0,0 +1,269 @@
// Interface for all container drivers
package drivers
import (
"context"
"errors"
"io"
"strings"
"time"
)
// A DriverCookie identifies a unique request to run a task.
//
// Clients should always call Close() on a DriverCookie after they are done
// with it.
type Cookie interface {
// Close should clean up any resources the cookie was using, or was going to use.
Close(ctx context.Context) error
// Run should execute task on the implementation.
// RunResult captures the result of task execution. This means if task
// execution fails due to a problem in the task, Run() MUST return a valid
// RunResult and nil as the error. The RunResult's Error() and Status()
// should be used to indicate failure.
// If the implementation itself suffers problems (lost of network, out of
// disk etc.), a nil RunResult and an error message is preferred.
//
// Run() MUST monitor the context. task cancellation is indicated by
// cancelling the context.
Run(ctx context.Context) (WaitResult, error)
}
type WaitResult interface {
// Wait may be called to await the result of a container's execution. If the
// provided context is canceled and the container does not return first, the
// resulting status will be 'canceled'. If the provided context times out
// then the resulting status will be 'timeout'.
Wait(context.Context) (RunResult, error)
}
type Driver interface {
// Prepare can be used in order to do any preparation that a specific driver
// may need to do before running the task, and can be useful to put
// preparation that the task can recover from into (i.e. if pulling an image
// fails because a registry is down, the task doesn't need to be failed). It
// returns a cookie that can be used to execute the task.
// Callers should Close the cookie regardless of whether they run it.
//
// The returned cookie should respect the task's timeout when it is run.
Prepare(ctx context.Context, task ContainerTask) (Cookie, error)
}
// RunResult indicates only the final state of the task.
type RunResult interface {
// Error is an actionable/checkable error from the container.
error
// Status should return the current status of the task.
// Only valid options are {"error", "success", "timeout", "killed", "cancelled"}.
Status() string
}
// The ContainerTask interface guides task execution across a wide variety of
// container oriented runtimes.
// This interface is unstable.
//
// FIXME: This interface is large, and it is currently a little Docker specific.
type ContainerTask interface {
// Command returns the command to run within the container.
Command() string
// EnvVars returns environment variable key-value pairs.
EnvVars() map[string]string
// Input feeds the container with data
Input() io.Reader
// The id to assign the container
Id() string
// Image returns the runtime specific image to run.
Image() string
// Timeout specifies the maximum time a task is allowed to run. Return 0 to let it run forever.
Timeout() time.Duration
// Driver will write output log from task execution to these writers. Must be
// non-nil. Use io.Discard if log is irrelevant.
Logger() (stdout, stderr io.Writer)
// WriteStat writes a single Stat, implementation need not be thread safe.
WriteStat(Stat)
// Volumes returns an array of 2-element tuples indicating storage volume mounts.
// The first element is the path on the host, and the second element is the
// path in the container.
Volumes() [][2]string
// Memory determines the max amount of RAM given to the container to use.
// 0 is unlimited.
Memory() uint64
// WorkDir returns the working directory to use for the task. Empty string
// leaves it unset.
WorkDir() string
// Close is used to perform cleanup after task execution.
// Close should be safe to call multiple times.
Close()
}
// Stat is a bucket of stats from a driver at a point in time for a certain task.
type Stat struct {
Timestamp time.Time
Metrics map[string]uint64
}
// Set of acceptable errors coming from container engines to TaskRunner
var (
// ErrOutOfMemory for OOM in container engine
ErrOutOfMemory = userError(errors.New("out of memory error"))
)
// TODO agent.UserError should be elsewhere
func userError(err error) error { return &ue{err} }
type ue struct {
error
}
func (u *ue) UserVisible() bool { return true }
// TODO: ensure some type is applied to these statuses.
const (
// task statuses
StatusRunning = "running"
StatusSuccess = "success"
StatusError = "error"
StatusTimeout = "timeout"
StatusKilled = "killed"
StatusCancelled = "cancelled"
)
type Config struct {
Docker string `json:"docker"`
// TODO CPUShares should likely be on a per container basis
CPUShares int64 `json:"cpu_shares"`
}
// for tests
func DefaultConfig() Config {
return Config{
Docker: "unix:///var/run/docker.sock",
CPUShares: 0,
}
}
func average(samples []Stat) (Stat, bool) {
l := len(samples)
if l == 0 {
return Stat{}, false
} else if l == 1 {
return samples[0], true
}
s := Stat{
Metrics: samples[0].Metrics, // Recycle Metrics map from first sample
}
t := samples[0].Timestamp.UnixNano() / int64(l)
for _, sample := range samples[1:] {
t += sample.Timestamp.UnixNano() / int64(l)
for k, v := range sample.Metrics {
s.Metrics[k] += v
}
}
s.Timestamp = time.Unix(0, t)
for k, v := range s.Metrics {
s.Metrics[k] = v / uint64(l)
}
return s, true
}
// Decimate will down sample to a max number of points in a given sample by
// averaging samples together. i.e. max=240, if we have 240 samples, return
// them all, if we have 480 samples, every 2 samples average them (and time
// distance), and return 240 samples. This is relatively naive and if len(in) >
// max, <= max points will be returned, not necessarily max: length(out) =
// ceil(length(in)/max) -- feel free to fix this, setting a relatively high max
// will allow good enough granularity at higher lengths, i.e. for max of 1 hour
// tasks, sampling every 1s, decimate will return 15s samples if max=240.
// Large gaps in time between samples (a factor > (last-start)/max) will result
// in a shorter list being returned to account for lost samples.
// Decimate will modify the input list for efficiency, it is not copy safe.
// Input must be sorted by timestamp or this will fail gloriously.
func Decimate(maxSamples int, stats []Stat) []Stat {
if len(stats) <= maxSamples {
return stats
} else if maxSamples <= 0 { // protect from nefarious input
return nil
}
start := stats[0].Timestamp
window := stats[len(stats)-1].Timestamp.Sub(start) / time.Duration(maxSamples)
nextEntry, current := 0, start // nextEntry is the index tracking next Stats record location
for x := 0; x < len(stats); {
isLastEntry := nextEntry == maxSamples-1 // Last bin is larger than others to handle imprecision
var samples []Stat
for offset := 0; x+offset < len(stats); offset++ { // Iterate through samples until out of window
if !isLastEntry && stats[x+offset].Timestamp.After(current.Add(window)) {
break
}
samples = stats[x : x+offset+1]
}
x += len(samples) // Skip # of samples for next window
if entry, ok := average(samples); ok { // Only record Stat if 1+ samples exist
stats[nextEntry] = entry
nextEntry++
}
current = current.Add(window)
}
return stats[:nextEntry] // Return slice of []Stats that was modified with averages
}
// https://github.com/fsouza/go-dockerclient/blob/master/misc.go#L166
func parseRepositoryTag(repoTag string) (repository string, tag string) {
parts := strings.SplitN(repoTag, "@", 2)
repoTag = parts[0]
n := strings.LastIndex(repoTag, ":")
if n < 0 {
return repoTag, ""
}
if tag := repoTag[n+1:]; !strings.Contains(tag, "/") {
return repoTag[:n], tag
}
return repoTag, ""
}
func ParseImage(image string) (registry, repo, tag string) {
repo, tag = parseRepositoryTag(image)
// Officially sanctioned at https://github.com/moby/moby/blob/master/registry/session.go#L319 to deal with "Official Repositories".
// Without this, token auth fails.
// Registries must exist at root (https://github.com/moby/moby/issues/7067#issuecomment-54302847)
// This cannot support the `library/` shortcut for private registries.
parts := strings.Split(repo, "/")
switch len(parts) {
case 1:
repo = "library/" + repo
case 2:
if strings.Contains(repo, ".") {
registry = parts[0]
repo = parts[1]
}
case 3:
registry = parts[0]
repo = parts[1] + "/" + parts[2]
}
if tag == "" {
tag = "latest"
}
return registry, repo, tag
}