►
From YouTube: Let's Build Kubernetes, With a Spreadsheet and Volunteers! - Justin Garrison, Independent
Description
Let's Build Kubernetes, With a Spreadsheet and Volunteers! - Justin Garrison, Independent
An introduction to the core responsibilities of Kubernetes. A visual representation of how Kubernetes works and what each component does. Building from nothing until we have a fully functional Kubernetes cluster built from people.
Our Kubernetes in meat space will teach you where to look when things break and help you remember what every component does. We'll show you how the system behaves when components fail and what you can do to fix it.
About Justin Garrison
Justin is the co-author of Cloud Native Infrastructure and has his name in multiple movie credits. What he enjoys most is helping people and learning new things. He likes to teach with unconventional approaches and being part of community.
Join us for KubeCon + CloudNativeCon in Barcelona May 20 - 23, Shanghai June 24 - 26, and San Diego November 18 - 21! Learn more at https://kubecon.io. The conference features presentations from developers and end users of Kubernetes, Prometheus, Envoy and all of the other CNCF-hosted projects.
A
A
Hopefully,
I'm
really
hoping
this
gonna
be
the
funnest
talk
you
go
to.
I
was
like
there's
a
lot
of
information
and
that's
flashing
is
gonna,
be
great,
but
I
really
just
hope
to
101
intro.
Everyone
gets
a
better
idea
of
how
kubernetes
works
fundamentals
that
would
be
bad
I
kind
of
need
that
one
Oh,
that's
because
I'm
not
plugged
in
but
okay
I'll
just
have
to
keep
doing
that.
Yeah.
I
really
hope
that
this
is
gonna,
be
just
a
fun
talk.
A
We
we
are
going
to
build
kubernetes
up
here
and
it
not
build
like
compile
like
you'll,
see
functionally
what
kubernetes
does
when
you
do
things.
So
that's
me
I'm
on
Twitter
a
lot.
If
you
want
to
DM
me,
I've,
diems,
open
or
or
ping
me
and
you
feedback
I
am
also
a
CNC
F
ambassador.
Nobody
really
knows
what
that
means,
but
I'm
in
the
group
of
ambassadors
that
kind
of
promote
cloud
native
computing
foundations
tools
as
being
one
of
them
and
a
lot
of
other
ones,
so
we're
here
we
do
there's
a
decent
size
group.
A
We
do
meetups
all
over
the
place,
but
it's
kind
of
a
fun
thing
to
do.
I
also
wrote
a
book
with
Chris
Nova
about
cloud
native
infrastructure.
So,
if
you
haven't
picked
that
up,
they
were
giving
them
away
yesterday,
a
little
bit
see
and
I
booked.
That
info
has
all
the
links.
If
you
actually
want
to
go,
get
one
really
appreciating
feedback
on
that.
A
I
actually
was
partially
inspired
by
the
quote
that
Sarah
had
in
the
keynote
today
from
Benjamin
Franklin,
where
it
was
tell
me
and
I
will
forget,
teach
me
and
I
may
remember
and
involve
me
and
I
will
learn,
and
so
that's
really
kind
of
like
getting
people
involved
and
how
this
stuff
works
and
visually
seen
it.
Now.
A
You
can
look
at
diagrams
all
day,
but
seeing
how,
where
the
failure
modes
are,
what
actually
happens,
I
think
is
really
powerful,
and
so
to
do
that,
you
know
what
LARPing
is
yeah,
so
it's
live
action,
role-playing
and
basically
you
dress
up.
You
go
somewhere
and
you
act
out
something
whether
it's
Civil,
War,
reenactments
or
corgis,
doing
the
great
battle
of
core
coppola
s--
whatever
whenever
that
took
place,
and
so
we're
gonna
we're
gonna
do
that
here,
live
on
stage.
I
already
have
some
some
plants
in
the
audience.
A
Thank
you
for
volunteering,
and
then
this
is
my
last
slide.
Everything
else
is
gonna
be
up
here,
but
this
is
just
kind
of
a
really
basic
overview
of
some
of
the
components
we're
gonna
go
over
and
some,
but
we're
not
going
to
go
over.
Mainly
the
control
plane
is,
is
the
backend
of
kubernetes.
What
really
involved,
what
kubernetes
deals
with
to
make
stuff
happen
inside
the
cluster
and
then
we're
also
gonna
have
nodes
or
super
important.
A
Anyone
remember
when
nodes
used
to
be
called
minions,
I
used
to
love
that
I,
don't
know
why
just
minions
sounded
so
cool
and
the
things
we're
not
gonna
go
over
are
those
add-ons
there.
Those
are
all
kind
of
implementation
details
a
lot
of
times
it's
some
of
them
like
DNS,
is
a
critical
piece
of
the
infrastructure,
but
a
that's
really
hard
to
represent
as
a
that
person
and
be
you
can
kind
of
switch
it
out.
You
don't
have
to
use
the
internal
kubernetes
dns
to
kind
of
solve
some
of
these
problems.
A
Almost
every
cluster
will
bring
one
for
you,
but
again
you
don't
have
to
so
with
that
I'm
gonna
go
ahead
and
show
you
how
we're
gonna
do
this
actually
wait?
Sorry,
let
me
skip
back
think
you
want
come
up,
so
Vic
has
graciously
volunteered
to
be
one
of
my
cubelets
and
and
the
cubelet
is
the
process
that
runs
on
a
node
we're
not
treating
nodes
as
cattle
today,
there's
no,
it
is
Texas,
but
there's
no
guns
allowed.
Where
gonna
take
care
of
this.
A
We
like
Vic
so
Vic's
job
as
a
cubelet,
is
to
run
pods,
and
that
is
his
main
job
he
needs
to.
Whenever
someone
tells
him
here's
a
pod
Vic
makes
sure
that
that's
the
thing
that
he
runs
and
he
makes
sure
that
always
runs
and
that's
it.
He
does
other
things
when
there's
a
cluster
but
as
a
standalone
cubelet
like
you,
can
take
a
server
and
run
the
cubelet
on
it
and
you're
fine,
you
can
just
okay.
Here
you
go.
Here's
your
here's,
your
stuff
I
mean
it's.
It's
not
a
lot
different
than
just
running.
A
Docker
docker
makes
sure
that
the
containers
that
it
runs
are
always
running
so
in
this
case,
with
with
Vic
we're
actually
starting
off
with.
We
have
what
we're
gonna
represent
as
pawns,
and
so
oh
I
told
you
it's
visual
come
on
we're.
This
is
gonna,
be
good,
and
let
me
tell
you
having
it:
oh,
no,
it
has
a
whole
weight
now.
We're
good
I
mean
a
bag
full
of
balloons
like
TSA.
It's
just
all
sorts
of
fun.
A
So
anyone
know
what
what
we're
doing
here.
What
is
this
app
Python
anyone
come
on,
went
through
a
lot
of
effort
to
get
that
there
we
go.
Thank
you.
This
is
like
their
color
as
a
whole.
See
I'm,
not
that
good,
no
wait,
wait,
I,
know
they're,
not
here
or
you
know,
if
I
have
a
bag,
so
it
doesn't
matter
so
we're
good,
but
this
isn't
just
any
it.
Yeah
I
think
we're
good.
A
So
this
is
actually
gonna
be
super
special
because
I
don't
use
Django
and
for
some
reason,
I
always
just
imagine
that
Django
was
like
a
dog
I.
Don't
know
why
it
just
seemed
like
a
good
dog
name,
so
we're
actually
gonna
have
Vic,
run
Django
and
keep
it
running
for
as
long
as
he
can
and
if
something
happens
to
it
at
your
job,
so
the
cubelet
again
you
keep
it
running
whatever
it
takes.
In
this
case,
this
is
gonna,
be
a
static
pod.
A
Static
pods
are
just
to
find
my
skills
doing
this,
while
talking
we're
not
super
practiced,
just
just
FYI,
it's
like
typing,
but
a
whole
nother
level
wait.
Okay,
his
legs
are
upside
down
there.
We
go
there's
the
dock
they're
staying
his
neck
pop,
but
that's
alright.
Okay,
it
actually
Django
2.0
came
out
so
there
we
go
special
little
in
for
ya.
So
as
a
static
pod,
you
can
define
these
on
the
node
as
just
gamelan
disk.
The
cubelet
comes
up.
He
reads
from
disk
and
says:
oh
look:
I
have
a
pod
to
run.
A
I'm
gonna
run
that
thing,
so
he
fetches
it
from
the
the
container
images
from
the
registry
which
is
going
to
be
my
bag
here,
full
of
balloons
for
when
other
people
come
up,
so
they
can
get
their
containers
out
of
the
container
registry.
Okay,
that's
even
talker
branded,
so
we,
but
it
can
be
whatever
you
want.
You
can
tell
it
what
registry
to
get
the
images
from,
and
he
just
runs
that
container
and
that's
his
job.
Alright,
we
just
built
kubernetes
right.
A
This
is
it
kind
of
it's
not
really
a
cluster
right
like
like
this
is
a
server
doing
this
thing.
This
is
no
different
than
when
people
used
to
go,
but
people
still
go
and
docker
run
some
thing
on
a
box
and-
and
it
runs
right-
that's
like
okay!
That's
not
very
special,
so
the
complexity
comes
when
we
now
want
to
VIX
right.
We
want
to
servers
to
run
containers
and
we're
gonna
not
manually.
Do
this
stuff
and
it's
not
going
to
be
things
on
disk.
It's
gonna
be
we're
gonna
dynamically.
Put
these
pods
everywhere.
A
A
We're
gonna
use
a
database
in
the
cloud
right.
That's
it
like
that's
your
thing.
It's
a
database
running
in
the
cloud
right
there.
So
talk
about
Alang
Alang
is
also
gonna,
be
one
of
my
nodes.
He
has
graciously
volunteered.
So
what
we
first
need
to
do
here
actually
I
take
out
my
notes
to
make
sure
I
do
this
right,
cuz
I
forget
things
so
much
there.
We
go
so
just
to
make
sure
so
we're
just
to
keep
a
database
of
typing
node.
In
order
to
identify
these
nodes,
we
don't
want
just
do
host
names.
A
That's
not
that's
not
really
special,
it's
not
always
unique,
so
we're
actually
gonna
sign
labels.
It's
how
pretty
much
we
do
everything
inside
of
kubernetes
there's
labels
everywhere.
If
you
don't
like
labels
product
you
something
else,
and
then
we're
just
gonna
track
what
pods
are
on?
There
will
paralyze
it
because
we
might
want
more
than
one
pod
later
on
so
first
off
we
have
Vic
and
we're
gonna.
Do
the
label
of
hop
out
hoodie?
Oh
wait!
I
got
and
beard
beard
I
like
it.
Okay
and
he's
running
our
she.
B
A
Pod
right
so
along
here,
he
is
can't
you
tell
he's
one
of
the
new
Amazon
metal
surfers.
So
he's
he's
a
metal
server,
we're
just
gonna
say
that
or
bear
handle
whatever
you
want,
he's
not
running
any
pods
right
now,
that's
fine!
He
you
know
we
haven't
scheduled
anything.
He
didn't
have
any
static,
pods
we're
fine!
So
let
me
just
add
a
divider
here,
so
it's
a
little
easier
to
track.
A
A
And
in
last
thing
we
need
to
check
is
where
they're
from
where
they're
actually
running
so
pods
also
have
labels
and
we
track
what
nodes
they
run
on.
In
this
case,
the
static
pod
never
actually
made
it
into
this
database
because
it
was
just
a
thing
on
disk
that
we
didn't
really
care
about.
So
if
we
want
to,
if
we
have
these
nodes
now
we
have
a
database.
How
did
they
know
how
to
talk
to
this
database?
How
do
they
get
their
information?
How
do
they
read
what
I
should
do
an
API
server?
A
They
they're
gonna,
not
talk
directly,
don't
hard-code
your
stuff
back
to
the
database
right,
don't
do
that,
so
we
have
an
API
server
that
sits
in
between
I'm
gonna
play
the
API
server
in
this
in
this
place,
I
am
the
only
one
that's
allowed
to
write
to
the
database.
They're
not
allowed
to
know
other
component
of
kubernetes
can
write
to
the
database,
only
the
API
servers
and
so
anything
that
they
need
they
they
read
through
me
and
then
they
they
can
write
back
any
component
unfortunate.
A
You
can't
really
see
the
screen,
but
hopefully
will
fill
you
in
on
some
of
this.
So
let's
go
ahead
and
run
another
application.
Someone
give
me
a
language
showers
coming
up.
I'm
gonna
do
Ruby
all
right,
let's
just
let's
just
do
Ruby
just
because
I
have
red
balloons
so
Ruby
as
the
label
Rhett.
Now
what
happens?
A
Nothing
they're,
not!
They
need
to
look
at
the
database
and
know
hey
what
pod
should
I
run,
but
how
do
I
get
a
pod
assigned
to
a
node
I
just
get
a
new
scheduler
I
need
something
that
actually
tells
me.
Oh,
that
goes
here
and
so
right
come
up
so
I'm
gonna,
add
another
divider
over
here.
Actually
here
cube
list
on
that
side.
If
you
can't
stand
right
over
here,
just
so
keep
it
visually.
A
Say:
hey
what's
assigned
to
me
what's
assigned
to
me:
if
there's
nothing,
they
do
nothing.
If
there's
something,
then
they
say
they
look
at
what
they're
currently
doing
and
what's
assigned-
and
they
say
hey-
is
that
right
and
they
they
reconcile.
They
say:
oh
I
need
to
do
something
or
I
don't
and
that's
it
and
that's
really
like
the
function
of
the
cubelet.
There
are
other
things
that
they'll
do
like.
They'll
have
ping
checks,
they'll
kind
of
notify
through
the
API
servers,
say
what
their
health
is
say.
What
features
they
have.
A
So
again,
who's
actually
creating
pods
inside
the
cluster.
Does
anyone
actually
like,
like
I,
want
this
pod?
It's
not
a
really
good
thing
to
do
inside
of
kubernetes,
because
it
doesn't.
If
you
want
to
scale
it,
you
gotta,
like
you
manually,
do
all
these
things.
So
when
you
actually
want
to
make
something
that
dynamically
scales,
you
typically
make
a
deployment
and
what
deployments
do
under
the
hood?
Is
they
make
what's
called
a
replica
set
replica?
Sets
you
sell
it,
how
many
it
wants,
and
then
that
creates
more
of
those
pods
and
it's
it's
super
awesome.
A
Labels
are
big
and
blue.
How
many
replicas
I
just
I'm,
just
gonna,
do
one
cuz,
I
wanna
kill
anyone
yet
so
we
now
have
someone
told
the
API
server
hey.
This
is
what
we
want
running.
This
should
always
be
running
in
this
cluster,
but
now
what
happens?
Nothing?
We!
We
don't
have
anything
that
creates
those
pods.
We
just
I
stored.
This
object
as
the
API
server
it's
in
the
database,
but
Chris
go
ahead
and
come
up
and
you'll
be
my
controller
manager.
You
can
stand
there
stand
here.
A
It's
either
way,
so
the
controller
manager
does
a
lot
of
unique
things
in
the
cluster.
It's
actually
like
four
or
five
different
things.
It's
hard
to
name
things.
One
of
the
things
the
controller
manager
does
is
looks
at
replicas
or
replicas
sets
and
just
figures
out
how
many
were
desired
and
how
many
are
running.
So
he
kind
of
keeps
track
of
what
the
actually
I
forgot,
you're
running,
that
Ruby
container
now
so
or
the
Ruby
pod.
So
there
you
go
I
almost
forgot
good
job,
so
he
needs
it
actually
creates
replicas
in
the
cluster.
A
Because
we
have,
we
have,
he
can
look
at
how
many
Java
replicas
we
wanted
and
how
many
pods
are
actually
used.
Those
same
labels
and
then
figure
out
like
oh
hey,
I
need
to
reconcile
that
state.
He
does
nothing
else.
He
creates
a
replicas
and
then
scheduler
over
here
will
then
assign
those
so
get
go
ahead.
We're
gonna,
say
Java,
give
me
a
name
will
is
randomly
name
these
things?
B
A
A
So
replication
controller
created
these
replicas
also
responsible
for
helping
out
when
nodes
come
and
go
inside
the
cluster.
So
so,
when
a
node
comes
up,
Ian's
you
want
when
a
node
comes
or
controller
manager
is
now
responsible
for
kind
of
making
sure
that
this
this
state
of
how
many
nodes
we
have
and
how
many
are
actually
declared
in
the
database,
matches
again
reconcile
state
just
figure
out
what's
different
and
see
what
was
desired
and
what's
different
Ian
now
came
up
he's
a
cubelet
in
the
cluster
and
so
we're
gonna
go
and
add
him.
A
A
Another
name
not
over
your
controller
manager.
You
need
to
tell
me
what
you're
creating
these
replicas
Jenny
Jenny
okay,
so
we
still
got
big
blue
same
labels
and
scheduler.
Obviously,
okay,
we're
gonna
go
to
ian's,
it's
really
hard
with
to
so
go
ahead.
Your
turn,
you
get
Java,
it's
it's
a
big
blue
one,
so
yeah
we're
just
going
through
the
cycle.
A
The
other
thing
that
the
controller
manager
is
responsible
for
whenever
there's
a
namespace
in
kubernetes.
There
are
default,
authentication
and
tokens-
don't
really
go
over
that
here,
but
it's
really
just
how
what
pods
can
talk
to
the
API
server
gives
access
to
other
things
inside
the
cluster
controller
manager
is
responsible
for
that.
The
other
thing
we
also
want
to
do
is
you're
gonna,
create
services.
Services
are
how
you
kind
of
route.
A
Cuz
pods
come
and
go
so
you
don't
really
so
service
you're
not
going
to
route
to
a
pod,
because
a
can
is
a
what's
up.
What's
that?
Oh
right,
thank
you
controller
manager.
What's
up
so
that's!
That's
a
good
point.
Let's
say:
nodes
came
up,
something
got
out
of
sync
on
the
API
and
you
say
what
what
happened
like?
What
where's
the
failure
points?
Okay,
like
all
sudden,
no
I,
if
I
look
at
the
cluster
I
have
this
mini,
but
something
else
is
wrong.
You
can
know
who
to
blame
right.
A
B
A
Good
point:
what
happens
if
sed
goes
away?
What
happens?
Has
anyone
ever
had
that
happen?
I?
Did
it
yeah
yeah?
It's
amazing,
you
know
what
happens
nothing.
They
keep
running,
they
know
what
they're
supposed
to
do.
They
had
to
do
nothing
else.
It's
fine!
No
one
can
talk
to
me.
I
can't
talk
to
the
database,
you
know
I'm
gonna
return,
404
loud
I,
don't
know
I
500
errors
like
I,
can't
do
it
right
now.
That's
okay!
Edd
can
go
away.
You
can't
change
anything.
The
cluster
will
stay
up,
I
had
it
down
for
days.
A
It
was
amazing
and
and
like
no
one
knew
no
one.
No
one
deploy
didn't
think
it
was.
It
was
amazing.
I
see
these
backups
back
awesome,
so
you're
right,
so
we
need.
We
need.
Java.
F
is
over
here
and
Java.
Jenny
is
here
so
now
back
to
our
services.
Of
course,
they
also
have
labels
trying
to
connect.
Alright,
that's
that's.
Fine
at
CDs,
gonna,
take
a
little
break
and
back
with
us
shortly.
So
in
the
meantime,.
A
Java
got
you
killed
right,
anyone
it's
like
who
knew
that
could
happen.
You
know,
what's
the
cubelets
job,
cublas
job
run
it
again
right,
go
fetch
that
image.
If
it
is
yeah,
that's
all
you
got
to
do
is
a
cube
list.
Yeah.
Luckily,
I
think
I
only
have
four
of
those.
So
but
that's
it.
The
cube
was
just
gonna,
go
back
in
and
and
run
this
thing,
because
that's
the
responsibility
of
the
cubelet
and
make
sure
what's
assigned
to
you
is
what
you're
doing
if
NCD
doesn't
come
back.
We're
gonna
have
a
hard
time.
Wait.
A
One
thing
I
will
say:
the
Wi-Fi
here
has
been
very
successful
for
me
overall
when
you
get
the
like
above
the
snowline
in
this
room
like
maybe
not
so
much
but
anyway,
so
labels
again
have
our
services
have
labels,
one
anything
that
services
have.
Is
they
actually
have
what
they
want
to
match
because
lay
the
service
itself
has
a
label.
That's
how
things
like
ingress
rules
and
other
things
will
match,
says:
they'll
find
a
service
which
is
a
stable
IP
address.
But
then
we
need
to
know
what
it
was.
A
So
we
know
controller
manager
again
is
responsible
to
that.
For
this
he
looks
at
the
cluster.
He
figures
out,
which
pods
have
those
labels
that
were
trying
to
match,
and
then
he
tells
the
API
server.
Oh
everything
with
this
this.
These
are
the
pods
that
match
that
label
so
which,
which
pod
is
it
they?
We
only
have
one.
Oh
it's
I'm.
Sorry,
it's
good!
It's
only
Ruby
at
this
point.
Yes
yeah
cuz.
We
didn't
create
that
for
a
replica
set.
That
was
just
connecting
every
time.
I
just
like
glance
at
the
Wi-Fi.
A
A
A
Yes,
if
at
CDs
down
and
that's
what
happened
before,
yeah
that
the
cubelet
already
knows,
this
is
my
definition.
He
can't
get
a
new
definition.
You
can't
change
what
he
knows,
but
he'll
look
at
the
API
server
and
say
like
well:
I'm
just
keep
earning
him.
What
I'm
doing
if
I
then
start
returning
five
hundreds
to
all
these
things,
then
they'll
just
say:
look
how
much
I
can
change
I'm
fine,
like
I,
know
what
I
had
to
run
last
time.
A
A
If
you
lose
the
node
yeah,
you
can't
change
the
state
of
the
cluster
so
yeah.
That
is
a
problem
going
on
vacation
for
a
little
bit.
But
so
what
happens?
Cuz
Django
is
out
of
the
cluster
right,
but
Django
wasn't
a
it
wasn't
actually
in
the
in
part
of
a
TV,
because
it
was
a
static
pod.
So
that's,
okay,
so
we're
not
gonna
rebalance
anything
we're
not
gonna
change
where
they
are
running.
It's
just
that's
fine
Vicks!
On
vacation.
We
don't
really
care
about
Django
in
this
play.
In
this
case.
A
A
Depends
depends
on
with
the
implementation
detail.
Your
your
container,
runtime
interface
determines
that
and
all
I
cases
defaults
docker.
If
it's
cryo,
it's
gonna
run
different
command.
If
it's
rocket
whatever
it
is
the
that
interface,
the
container
runtime
interface,
tells
the
cubelet
how
to
interact
and
how
to
do
something
with
this
pod.
A
And
so,
if
you
notice
on,
if
you're
running
docker,
you
have
at
least
pause
containers,
because
docker
doesn't
actually
have
a
default
way
to
make
a
group
of
containers
in
one
thing,
so
they
have
this
pause
container
and
they
layer
all
the
containers
on
top
of
it.
If
you're
using
something
like
rocket
or
cryo,
they
do
that
by
default.
You're
not
gonna
have
a
pause
container
because
it
just
it
can
do
that
already.
So
it
looks
a
little
bit
different
depending
on
the
implementation.
A
Right
we're
taking
it
to
the
offline
we're
not
running
in
the
cloud
anymore.
That
was
databases
in
the
cloud.
Maybe
not
so
much
do
I
have
Excel
installed.
I!
Think
I
do
okay,
we're
gonna,
leave
it
right
now,
defecated
nodes,
yes,
don't
run
in
the
cluster,
so
another!
Another
thought
is
how
do
you?
How
do
you
have
highly
available
API
server?
What
do
you
do
sure
now?
You
start.
A
Clusters
over
Wi-Fi
bad
idea,
so
second
API
server.
That's
all
you
have
to
do
create
another
one.
I'm
just
gonna,
Kelsey
doesn't
even
know
I'm
doing
this.
I'm
gonna
share
it
with
Kelsey
he's
gonna,
be
my
other
API
server
all
right
and
if
I
share
with
him
any
any
one
of
these
components
can
now
talk
directly
to
Kelsey.
He
has
write
access
to
this
database.
Still.
No
one
else
does,
but
that's
all
you
do
and
then
you
load
balance
your
API
servers.
I,
don't
need
to
know
Kelsey
state.
A
If
he's
down
that's
fine
people,
people
will
fail
when
they
talk
to
him
and
and
succeed.
For
me,
that's
totally
fine
same
thing
with
your
actual
components.
How
do
you
load
balance
a
API
server?
Sorry,
the
scheduler
and
controller
manager?
It
it's
slightly
different.
You
can
add
one
right
in
those
cases
they
can't
they
can't
directly
nct's
gonna
handle
locks
for
them,
but
they
can
actually
figure
out
master
election
in
SED,
so
they
can
say:
hey
I'm
the
leader
right
now.
A
Everyone
else
you
can
only
read,
and
so,
if
you
have
one
or
five
it'll,
get
a
lock
in
net
CD
and
say:
hey
I'm,
the
master
scheduler
right
now.
No
one
else
can
schedule
anything
and
that's
fine,
because
it
you
only
want
one
thing
doing
that
scheduling.
You
can
have
multiple
schedulers.
You
can
assign
those
things
with
annotations
and
and
run
these
things,
but
per
schedule
type
or
whatever.
You
can
only
have
one
scheduler.
A
We're
gonna
do
one
more
thing
here
and
I
want
to
show
Michael.
Can
you
come
up?
You're
gonna,
be
my
there's
other
things
that
a
lot
of
things
that
we're
just
trying
to
I'm
just
trying
to
give
some
basics
here.
Michael
is
gonna,
actually
be
my
initializer.
Anyone
know
what
an
initializer
does
it
initializes
pods
it
changes
them
in
some
way.
There
are
other
things
called
pod,
presets
and
admission
controllers.
Those
are
built
into
the
API
server.
A
So
when
someone
says
I
want
to
run
this
application,
the
API
server
will
change
it
somehow
by
either
saying
like
no
you're
not
allowed
like
I.
Don't
accept
that
container
like
I,
don't
want
Java
in
my
cluster,
I
can
say
no
Java
and
the
API
server
just
won't,
allow
it.
It
says
nope
that
you're
not
allowed
to
do
that.
A
Their
pod,
presets
and
and
the
ignition
controllers
are
really
cool,
but
they're
hard-coded
in
the
API
server.
And
if
you
want
to
change
them
free
boot,
the
API
server
you
have
to
or
compile
your
own,
it
wasn't
super
flexible.
It
was
kind
of
a
v1
of
being
able
to
modify
things
as
they
came
into
the
cluster,
so
they
introduced
recently
initializers,
which
I
think
are
alpha
and
one
night.
But
anyone
go
into
an
sto
talk,
that's
what
it
uses.
It's
an
initializer
in
the
cluster.
A
So
when
something
comes
in
one
thing
that
we
add
to
these
pods
right,
as
we
add
an
annotation,
so
someone
I
heard
go
earlier,
so
we're
gonna
say
we
got
another
one,
let's
just
say
we'll
make
it
read
to
and
we're
gonna
say
we
want
two
of
those.
So
you
have
go
names
Bob
and
go
not
Bob,
awesome,
red
red
scheduler.
B
B
B
A
A
Literally,
that's
what
we're
gonna
do
when
I
create
this
thing.
Now
the
API
server
says:
hey
I
created
this
thing:
I
haven't
config
for
initializer,
so
I
need
the
initializer
to
tell
me
if
it's
ready
or
not,
you
can
have
multiple
of
these.
You
can
chain
them
and
say:
oh
here's,
initializer
1
&
2,
&
3.
A
B
A
We
got
don't
worry,
we
got
this
Java
containers
in
each
one,
but
then
Michael
here
is
gonna
say
it's
go
and
it's
envoy
going
envoy.
So
now
the
containers
in
there
so
do
we
assign
it
yeah
you're
good,
wait,
wait,
wait,
wait,
hold
on
initializer,
then
tells
me,
is
it
initialized?
Well
I
mean
it
isn't.
In
is
the
object
in
the
database
initialized,
it's
yeah.
A
Okay,
we
are
we're.
Initialized
go
there's
a.
There
are
pink
balloons
in
there.
That
is
envoy
color
coding
is.
This
is
good.
If
you
rub
it
on
your
head,
really
good,
you
can
probably
get
this
go.
Oh,
we
didn't
begin
to
color.
There
were
no
go
for
balloons,
you
know
how
much
I
looked
for
gopher
balloons
and
I
could
not
find
the
ones
oh
no.
So
this
is
what
we're
doing
sure
yeah
yeah
we
got
to
schedule
so
go
ahead
and
blow
those
up
clusters.
A
It's
only
one
left,
so
one
other
thing
that
I
noticed
here
was
see
these
labels
on
on
go.
We
labeled
it
red.
We
wanted
to
match
red
for
our
service
right,
so
what's
gonna
happen,
controller
manager
does
that
match
this
thing?
Well,
no,
the
the
go.
App
is
labeled
red
and
we
wanted
to
match
label
red.
So
now
we
have
go
Bob
and
go,
but
that's
a
problem,
because
the
service
doesn't
know
that
it's
a
different
app.
The
service
is
just
matching
on
labels.
A
So
really-
and
that's
that
is
the
job
of
initializer
and
again
careful
with
initializers.
If
you
make
another
slider
config
and
you
try
to
start
your
initializer
guess
what
he
can't
initialize
himself.
So
there
are
some
of
those
chicken
X's
you
need
to
worry
about.
You
can
tell
it
I,
don't
ever
want
initialize
this
namespace
or
this
this
pod
or
whatever
it
is,
but
that's
literally,
here's
our
cubelets,
here's
initializer
controller
manager
and
API
server
and
that's
kubernetes.
Thank
you.
A
B
A
Pod
gets
deleted
and
then
the
controller
manager
says
hey.
I
need
two
of
those
things:
they're
not
I,
don't
have
to.
It
creates
another
one.
The
scheduler
then
looks
and
says:
oh
I
have
a
new
thing
which
cubelets
are
available
and
schedules
them
it's
the
same
process.
It
just
deletes
a
pod.
It
says:
oh
as
they're,
evacuating
we're
just
gonna
delete
those
things.
The
cubelet
then
says:
I
don't
have
to
do.
This
drop
some
fine
I'm
out
yeah.
B
A
A
Ideally,
four
so
a
custom
resource
definitions
ideally
would
have
their
own
scheduler
or
their
own
controller,
and
so
those
would
you
would
apply
an
annotation
that
says
I
want
to
use.
This
is
a
custom
resource
definition
and
your
scheduler
inside
of
it
is
only
going
to
look
at
those
definitions,
and
so
the
default
scheduler
doesn't
know
anything
about
your
CR
DS.
So
it's
not
gonna
do
anything
with
it.
It's
just
gonna
say:
hey.
Do
I
have
anything
that
is
they
actually
will
get
an
annotation.
That's
like
hey.
A
If
it
doesn't
have
an
annotation
here
for
a
different
scheduler,
then
I
will
look
at
it,
but
if
it
does
I
don't
care
I'm,
not
gonna,
look
at
it.
They
only
look
at
their
specific
thing
and
they
do
control
loops
on
that.
They
just
reconcile
all
right.
Please
give
the
cluster
a
hand
and
thanks
for
coming.