8.3 KiB
CRI-O Tutorial
This tutorial will walk you through the installation of CRI-O, an Open Container Initiative-based implementation of Kubernetes Container Runtime Interface, and the creation of Redis server running in a Pod.
Prerequisites
A Linux machine is required to download and build the CRI-O components and run the commands in this tutorial.
Create a machine running Ubuntu 16.10:
gcloud compute instances create cri-o \
--machine-type n1-standard-2 \
--image-family ubuntu-1610 \
--image-project ubuntu-os-cloud
SSH into the machine:
gcloud compute ssh cri-o
Installation
This section will walk you through installing the following components:
- crio - The implementation of the Kubernetes CRI, which manages Pods.
- crictl - The CRI client for testing.
- cni - The Container Network Interface
- runc - The OCI runtime to launch the container
runc
Download the runc release binary:
wget https://github.com/opencontainers/runc/releases/download/v1.0.0-rc4/runc.amd64
Set the executable bit and copy the runc binary into your PATH:
chmod +x runc.amd64
sudo mv runc.amd64 /usr/bin/runc
Print the runc version:
runc -version
runc version 1.0.0-rc4
commit: 2e7cfe036e2c6dc51ccca6eb7fa3ee6b63976dcd
spec: 1.0.0
crio
The crio project does not ship binary releases so you'll need to build it from source.
Install the Go runtime and tool chain
Download the Go 1.8.5 binary release:
wget https://storage.googleapis.com/golang/go1.8.5.linux-amd64.tar.gz
Install Go 1.8.5:
sudo tar -xvf go1.8.5.linux-amd64.tar.gz -C /usr/local/
mkdir -p $HOME/go/src
export GOPATH=$HOME/go
export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin
At this point the Go 1.8.5 tool chain should be installed:
go version
go version go1.8.5 linux/amd64
Get crictl
go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
Build crio from source
sudo apt-get update && apt-get install -y libglib2.0-dev \
libseccomp-dev \
libapparmor-dev \
libgpgme11-dev \
libdevmapper-dev \
make \
git
go get -d github.com/kubernetes-incubator/cri-o
cd $GOPATH/src/github.com/kubernetes-incubator/cri-o
make install.tools
make
sudo make install
If you are installing for the first time, generate and install configuration files with:
sudo make install.config
Start the crio system daemon
sudo sh -c 'echo "[Unit]
Description=OCI-based implementation of Kubernetes Container Runtime Interface
Documentation=https://github.com/kubernetes-incubator/cri-o
[Service]
ExecStart=/usr/local/bin/crio --log-level debug
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target" > /etc/systemd/system/crio.service'
sudo systemctl daemon-reload
sudo systemctl enable crio
sudo systemctl start crio
Ensure the crio service is running
sudo crictl --runtime-endpoint /var/run/crio/crio.sock info
Version: 0.1.0
RuntimeName: cri-o
RuntimeVersion: 1.10.0-dev
RuntimeApiVersion: v1alpha1
to avoid set --runtime-endpoint when call crictl, you can export $CRI_RUNTIME_ENDPOINT=/var/run/crio/crio.sock or cp crictl.yaml /etc/crictl.yaml from this repo
CNI plugins
This tutorial will use the latest version of CNI plugins from the master branch and build it from source.
Download the CNI plugins source tree:
go get -d github.com/containernetworking/plugins
cd $GOPATH/src/github.com/containernetworking/plugins
Build the CNI plugins:
./build.sh
Output:
Building API
Building reference CLI
Building plugins
flannel
tuning
bridge
ipvlan
loopback
macvlan
ptp
dhcp
host-local
noop
Install the CNI plugins:
sudo mkdir -p /opt/cni/bin
sudo cp bin/* /opt/cni/bin/
Configure CNI
sudo mkdir -p /etc/cni/net.d
sudo sh -c 'cat >/etc/cni/net.d/10-mynet.conf <<-EOF
{
"cniVersion": "0.2.0",
"name": "mynet",
"type": "bridge",
"bridge": "cni0",
"isGateway": true,
"ipMasq": true,
"ipam": {
"type": "host-local",
"subnet": "10.88.0.0/16",
"routes": [
{ "dst": "0.0.0.0/0" }
]
}
}
EOF'
sudo sh -c 'cat >/etc/cni/net.d/99-loopback.conf <<-EOF
{
"cniVersion": "0.2.0",
"type": "loopback"
}
EOF'
Install skopeo-containers package from ppa:projectatomic/ppa
sudo add-apt-repository ppa:projectatomic/ppa
sudo apt-get update
sudo apt-get install skopeo-containers -y
Restart crio in order to apply CNI config
systemctl restart crio
At this point CNI is installed and configured to allocation IP address to containers from the 10.88.0.0/16 subnet.
Pod Tutorial
Now that the CRI-O components have been installed and configured we are ready to create a Pod. This section will walk you through launching a Redis server in a Pod. Once the Redis server is running we'll use telnet to verify it's working, then we'll stop the Redis server and clean up the Pod.
Creating a Pod
First we need to setup a Pod sandbox using a Pod configuration, which can be found in the cri-o source tree:
cd $GOPATH/src/github.com/kubernetes-incubator/cri-o
Next create the Pod and capture the Pod ID for later use:
POD_ID=$(sudo crictl runp test/testdata/sandbox_config.json)
sudo crictl runp test/testdata/sandbox_config.json
Use the crictl command to get the status of the Pod:
sudo crictl inspectp --output table $POD_ID
Output:
ID: cd6c0883663c6f4f99697aaa15af8219e351e03696bd866bc3ac055ef289702a
Name: podsandbox1
UID: redhat-test-crio
Namespace: redhat.test.crio
Attempt: 1
Status: SANDBOX_READY
Created: 2016-12-14 15:59:04.373680832 +0000 UTC
Network namespace: /var/run/netns/cni-bc37b858-fb4d-41e6-58b0-9905d0ba23f8
IP Address: 10.88.0.2
Labels:
group -> test
Annotations:
owner -> hmeng
security.alpha.kubernetes.io/seccomp/pod -> unconfined
security.alpha.kubernetes.io/sysctls -> kernel.shm_rmid_forced=1,net.ipv4.ip_local_port_range=1024 65000
security.alpha.kubernetes.io/unsafe-sysctls -> kernel.msgmax=8192
Create a Redis container inside the Pod
Use the crictl command to pull the redis image, create a redis container from a container configuration and attach it to the Pod created earlier:
sudo crictl pull redis:alpine
CONTAINER_ID=$(sudo crictl create $POD_ID test/testdata/container_redis.json test/testdata/sandbox_config.json)
sudo crictl create $POD_ID test/testdata/container_redis.json test/testdata/sandbox_config.json
The crictl create command will take a few seconds to return because the redis container needs to be pulled.
Start the Redis container:
sudo crictl start $CONTAINER_ID
Get the status for the Redis container:
sudo crictl inspect $CONTAINER_ID
Output:
ID: d0147eb67968d81aaddbccc46cf1030211774b5280fad35bce2fdb0a507a2e7a
Name: podsandbox1-redis
Status: CONTAINER_RUNNING
Created: 2016-12-14 16:00:42.889089352 +0000 UTC
Started: 2016-12-14 16:01:56.733704267 +0000 UTC
Test the Redis container
Connect to the Pod IP on port 6379:
telnet 10.88.0.2 6379
Trying 10.88.0.2...
Connected to 10.88.0.2.
Escape character is '^]'.
At the prompt type MONITOR:
Trying 10.88.0.2...
Connected to 10.88.0.2.
Escape character is '^]'.
MONITOR
+OK
Exit the telnet session by typing ctrl-] and quit at the prompt:
^]
telnet> quit
Connection closed.
Viewing the Redis logs
The Redis logs are logged to the stderr of the crio service, which can be viewed using journalctl:
sudo journalctl -u crio --no-pager
Stop the redis container and delete the Pod
sudo crictl stop $CONTAINER_ID
sudo crictl rm $CONTAINER_ID
sudo crictl stopp $POD_ID
sudo crictl rmp $POD_ID
sudo crictl pods
sudo crictl ps