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AWS: Change master to m3.medium by default

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m3.large for > 150 nodes.

t2.micro often runs out of memory.  The t2 class has very
difficult-to-understand behaviour when it runs out of CPU.  The
m3.medium is reasonably affordable, and avoids these problems.

Fix #21151

Issue #18975
This commit is contained in:
Justin Santa Barbara
2016-02-12 11:05:56 -05:00
parent b5c12d10b8
commit a16372ce40
3 changed files with 40 additions and 13 deletions
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8
cluster/aws/config-default.sh
View File

@@ -33,12 +33,10 @@ fi
# Dynamically set the master size by the number of nodes, these are guesses
# TODO: gather some data
if [[ -z ${MASTER_SIZE} ]]; then
if (( ${NUM_NODES} < 50 )); then
MASTER_SIZE="t2.micro"
elif (( ${NUM_NODES} < 150 )); then
MASTER_SIZE="t2.small"
if (( ${NUM_NODES} < 150 )); then
MASTER_SIZE="m3.medium"
else
MASTER_SIZE="t2.medium"
MASTER_SIZE="m3.large"
fi
fi

8
cluster/aws/config-test.sh
View File

@@ -34,12 +34,10 @@ fi
# Dynamically set the master size by the number of nodes, these are guesses
# TODO: gather some data
if [[ -z ${MASTER_SIZE} ]]; then
if (( ${NUM_NODES} < 50 )); then
MASTER_SIZE="t2.micro"
elif (( ${NUM_NODES} < 150 )); then
MASTER_SIZE="t2.small"
if (( ${NUM_NODES} < 150 )); then
MASTER_SIZE="m3.medium"
else
MASTER_SIZE="t2.medium"
MASTER_SIZE="m3.large"
fi
fi

37
docs/getting-started-guides/aws.md
View File

@@ -85,6 +85,7 @@ You can override the variables defined in [config-default.sh](http://releases.k8
```bash
export KUBE_AWS_ZONE=eu-west-1c
export NUM_NODES=2
export MASTER_SIZE=m3.medium
export NODE_SIZE=m3.medium
export AWS_S3_REGION=eu-west-1
export AWS_S3_BUCKET=mycompany-kubernetes-artifacts
@@ -92,14 +93,44 @@ export INSTANCE_PREFIX=k8s
...
```
If you don't specify master and minion sizes, the scripts will attempt to guess the correct size of the master and worker nodes based on `${NUM_NODES}`. In
particular, for clusters less than 50 nodes it will use a `t2.micro`, for clusters between 50 and 150 nodes it will use a `t2.small` and for clusters with
greater than 150 nodes it will use a `t2.medium`.
If you don't specify master and minion sizes, the scripts will attempt to guess
the correct size of the master and worker nodes based on `${NUM_NODES}`. In
version 1.2 these default are:
* For the master, for clusters of less than 150 nodes it will use an
`m3.medium`, for clusters of greater than 150 nodes it will use an
`m3.large`.
* For worker nodes, for clusters less than 50 nodes it will use a `t2.micro`,
for clusters between 50 and 150 nodes it will use a `t2.small` and for
clusters with greater than 150 nodes it will use a `t2.medium`.
WARNING: beware that `t2` instances receive a limited number of CPU credits per hour and might not be suitable for clusters where the CPU is used
consistently. As a rough estimation, consider 15 pods/node the absolute limit a `t2.large` instance can handle before it starts exhausting its CPU credits
steadily, although this number depends heavily on the usage.
In prior versions of kubernetes, we defaulted the master node to a t2-class
instance, but found that this sometimes gave hard-to-diagnose problems when the
master ran out of memory or CPU credits. If you are running a test cluster
and want to save money, you can specify `export MASTER_SIZE=t2.micro` but if
your master pauses do check the CPU credits in the AWS console.
For production usage, we recommend at least `export MASTER_SIZE=m3.medium` and
`export NODE_SIZE=m3.medium`. And once you get above a handful of nodes, be
aware that one m3.large instance has more storage than two m3.medium instances,
for the same price.
We generally recommend the m3 instances over the m4 instances, because the m3
instances include local instance storage. Historically local instance storage
has been more reliable than AWS EBS, and performance should be more consistent.
The ephemeral nature of this storage is a match for ephemeral container
workloads also!
If you use an m4 instance, or another instance type which does not have local
instance storage, you may want to increase the `NODE_ROOT_DISK_SIZE` value,
although the default value of 32 is probably sufficient for the smaller
instance types in the m4 family.
The script will also try to create or reuse a keypair called "kubernetes", and IAM profiles called "kubernetes-master" and "kubernetes-minion".
If these already exist, make sure you want them to be used here.