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modify ipvs readme

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Lion-Wei 2018-06-07 14:36:29 +08:00
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pkg/proxy/ipvs/README.md
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@ -30,174 +30,233 @@ and UDP-based services to the real servers, and make services of real servers ap
IPVS mode was introduced in Kubernetes v1.8 and goes beta in v1.9. IPTABLES mode was added in v1.1 and become the default operating mode since v1.2. Both IPVS and IPTABLES are based on `netfilter`.
Differences between IPVS mode and IPTABLES mode are as follows:
1. IPVS provides better scalability and performance for large clusters.
1. IPVS provides better scalability and performance for large clusters.
2. IPVS supports more sophisticated load balancing algorithms than iptables (least load, least connections, locality, weighted, etc.).
2. IPVS supports more sophisticated load balancing algorithms than iptables (least load, least connections, locality, weighted, etc.).
3. IPVS supports server health checking and connection retries, etc.
### When ipvs falls back to iptables
IPVS proxier will employ iptables in doing packet filtering, SNAT and supporting NodePort type service. Specifically, ipvs proxier will fall back on iptables in the following 4 scenarios.
IPVS proxier will employ iptables in doing packet filtering, SNAT or masquerade.
Specifically, ipvs proxier will use ipset to store source or destination address of traffics that need DROP or do masquared, to make sure the number of iptables rules be constant, no metter how many services we have.
Here is the table of ipset sets that ipvs proxier used.
| set name | members | usage |
| :----------------------------- | ---------------------------------------- | ---------------------------------------- |
| KUBE-CLUSTER-IP | All service IP + port | Mark-Masq for cases that `masquerade-all=true` or `clusterCIDR` specified |
| KUBE-LOOP-BACK | All service IP + port + IP | masquerade for solving hairpin purpose |
| KUBE-EXTERNAL-IP | service external IP + port | masquerade for packages to external IPs |
| KUBE-LOAD-BALANCER | load balancer ingress IP + port | masquerade for packages to load balancer type service |
| KUBE-LOAD-BALANCER-LOCAL | LB ingress IP + port with `externalTrafficPolicy=local` | accept packages to load balancer with `externalTrafficPolicy=local` |
| KUBE-LOAD-BALANCER-FW | load balancer ingress IP + port with `loadBalancerSourceRanges` | package filter for load balancer with `loadBalancerSourceRanges` specified |
| KUBE-LOAD-BALANCER-SOURCE-CIDR | load balancer ingress IP + port + source CIDR | package filter for load balancer with `loadBalancerSourceRanges` specified |
| KUBE-NODE-PORT-TCP | nodeport type service TCP port | masquerade for packets to nodePort(TCP) |
| KUBE-NODE-PORT-LOCAL-TCP | nodeport type service TCP port with `externalTrafficPolicy=local` | accept packages to nodeport service with `externalTrafficPolicy=local` |
| KUBE-NODE-PORT-UDP | nodeport type service UDP port | masquerade for packets to nodePort(UDP) |
| KUBE-NODE-PORT-LOCAL-UDP | nodeport type service UDP port with `externalTrafficPolicy=local` | accept packages to nodeport service with `externalTrafficPolicy=local` |
IPVS proxier will fall back on iptables in the following scenarios.
**1. kube-proxy starts with --masquerade-all=true**
If kube-proxy starts with `--masquerade-all=true`, ipvs proxier will masquerade all traffic accessing service Cluster IP, which behaves the same as what iptables proxier. Suppose there is a service with Cluster IP `10.244.5.1` and port `8080`, then the iptables installed by ipvs proxier should be like what is shown below.
If kube-proxy starts with `--masquerade-all=true`, ipvs proxier will masquerade all traffic accessing service Cluster IP, which behaves the same as what iptables proxier. Suppose kube-proxy have flag `--masquerade-all=true` specified, then the iptables installed by ipvs proxier should be like what is shown below.
```shell
# iptables -t nat -nL
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
Chain KUBE-MARK-DROP (0 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x8000
Chain KUBE-MARK-MASQ (6 references)
target prot opt source destination
Chain KUBE-MARK-MASQ (2 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ tcp -- 0.0.0.0/0 10.244.5.1 /* default/foo:http cluster IP */ tcp dpt:8080
target prot opt source destination
KUBE-MARK-MASQ all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst
```
**2. Specify cluster CIDR in kube-proxy startup**
If kube-proxy starts with `--cluster-cidr=<cidr>`, ipvs proxier will masquerade off-cluster traffic accessing service Cluster IP, which behaves the same as what iptables proxier. Suppose kube-proxy is provided with the cluster cidr `10.244.16.0/24`, and service Cluster IP is `10.244.5.1` and port is `8080`, then the iptables installed by ipvs proxier should be like what is shown below.
If kube-proxy starts with `--cluster-cidr=<cidr>`, ipvs proxier will masquerade off-cluster traffic accessing service Cluster IP, which behaves the same as what iptables proxier. Suppose kube-proxy is provided with the cluster cidr `10.244.16.0/24`, then the iptables installed by ipvs proxier should be like what is shown below.
```shell
# iptables -t nat -nL
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
Chain KUBE-MARK-DROP (0 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x8000
Chain KUBE-MARK-MASQ (6 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ tcp -- !10.244.16.0/24 10.244.5.1 /* default/foo:http cluster IP */ tcp dpt:8080
```
**3. Load Balancer Source Ranges is specified for LB type service**
When service's `LoadBalancerStatus.ingress.IP` is not empty and service's `LoadBalancerSourceRanges` is specified, ipvs proxier will install iptables which looks like what is shown below.
Suppose service's `LoadBalancerStatus.ingress.IP` is `10.96.1.2` and service's `LoadBalancerSourceRanges` is `10.120.2.0/24`.
```shell
# iptables -t nat -nL
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
Chain KUBE-MARK-DROP (0 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x8000
Chain KUBE-MARK-MASQ (6 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-SERVICES (2 references)
target prot opt source destination
ACCEPT tcp -- 10.120.2.0/24 10.96.1.2 /* default/foo:http loadbalancer IP */ tcp dpt:8080
DROP tcp -- 0.0.0.0/0 10.96.1.2 /* default/foo:http loadbalancer IP */ tcp dpt:8080
```
**4. Support NodePort type service**
For supporting NodePort type service, ipvs will recruit the existing implementation in iptables proxier. For example,
```shell
# kubectl describe svc nginx-service
Name: nginx-service
...
Type: NodePort
IP: 10.101.28.148
Port: http 3080/TCP
NodePort: http 31604/TCP
Endpoints: 172.17.0.2:80
Session Affinity: None
# iptables -t nat -nL
[root@100-106-179-225 ~]# iptables -t nat -nL
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ tcp -- !172.16.0.0/16 10.101.28.148 /* default/nginx-service:http cluster IP */ tcp dpt:3080
KUBE-SVC-6IM33IEVEEV7U3GP tcp -- 0.0.0.0/0 10.101.28.148 /* default/nginx-service:http cluster IP */ tcp dpt:3080
KUBE-NODEPORTS all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service nodeports; NOTE: this must be the last rule in this chain */ ADDRTYPE match dst-type LOCAL
Chain KUBE-NODEPORTS (1 references)
target prot opt source destination
KUBE-MARK-MASQ tcp -- 0.0.0.0/0 0.0.0.0/0 /* default/nginx-service:http */ tcp dpt:31604
KUBE-SVC-6IM33IEVEEV7U3GP tcp -- 0.0.0.0/0 0.0.0.0/0 /* default/nginx-service:http */ tcp dpt:31604
Chain KUBE-SVC-6IM33IEVEEV7U3GP (2 references)
target prot opt source destination
KUBE-SEP-Q3UCPZ54E6Q2R4UT all -- 0.0.0.0/0 0.0.0.0/0 /* default/nginx-service:http */
Chain KUBE-SEP-Q3UCPZ54E6Q2R4UT (1 references)
target prot opt source destination
KUBE-MARK-MASQ all -- 172.17.0.2 0.0.0.0/0 /* default/nginx-service:http */
DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 /* default/nginx-service:http */ tcp to:172.17.0.2:80
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-MARK-MASQ (3 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ all -- !10.244.16.0/24 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst
```
**3. Load Balancer type service**
For loadBalancer type service, ipvs proxier will install iptables with match of ipset `KUBE-LOAD-BALANCER`.
Specially when service's `LoadBalancerSourceRanges` is specified or specified `externalTrafficPolicy=local`,
ipvs proxier will create ipset sets `KUBE-LOAD-BALANCER-LOCAL`/`KUBE-LOAD-BALANCER-FW`/`KUBE-LOAD-BALANCER-SOURCE-CIDR`
and install iptables accordingly, which should looks like what is shown below.
```shell
# iptables -t nat -nL
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-FIREWALL (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOAD-BALANCER-SOURCE-CIDR dst,dst,src
KUBE-MARK-DROP all -- 0.0.0.0/0 0.0.0.0/0
Chain KUBE-LOAD-BALANCER (1 references)
target prot opt source destination
KUBE-FIREWALL all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOAD-BALANCER-FW dst,dst
RETURN all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOAD-BALANCER-LOCAL dst,dst
KUBE-MARK-MASQ all -- 0.0.0.0/0 0.0.0.0/0
Chain KUBE-MARK-DROP (1 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x8000
Chain KUBE-MARK-MASQ (2 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-LOAD-BALANCER all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOAD-BALANCER dst,dst
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOAD-BALANCER dst,dst
```
**4. NodePort type service**
For NodePort type service, ipvs proxier will install iptables with match of ipset `KUBE-NODE-PORT-TCP/KUBE-NODE-PORT-UDP`.
When specified `externalTrafficPolicy=local`,ipvs proxier will create ipset sets `KUBE-NODE-PORT-LOCAL-TC/KUBE-NODE-PORT-LOCAL-UDP`
and install iptables accordingly, which should looks like what is shown below.
Suppose service with TCP type nodePort.
```shell
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-MARK-MASQ (2 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-NODE-PORT (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-NODE-PORT-LOCAL-TCP dst
KUBE-MARK-MASQ all -- 0.0.0.0/0 0.0.0.0/0
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-NODE-PORT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-NODE-PORT-TCP dst
```
**5. Service with externalIPs specified**
For service with `externalIPs` specified, ipvs proxier will install iptables with match of ipset `KUBE-EXTERNAL-IP`,
Suppose we have service with `externalIPs` specified, iptables rules should looks like what is shown below.
```shell
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
Chain KUBE-MARK-MASQ (2 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000
Chain KUBE-POSTROUTING (1 references)
target prot opt source destination
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-EXTERNAL-IP dst,dst
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-EXTERNAL-IP dst,dst PHYSDEV match ! --physdev-is-in ADDRTYPE match src-type !LOCAL
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-EXTERNAL-IP dst,dst ADDRTYPE match dst-type LOCAL
```
## Run kube-proxy in ipvs mode
Currently, local-up scripts, GCE scripts and kubeadm support switching IPVS proxy mode via exporting environment variables or specifying flags.
Currently, local-up scripts, GCE scripts and kubeadm support switching IPVS proxy mode via exporting environment variables or specifying flags.
### Prerequisite
Ensure IPVS required kernel modules
@ -248,13 +307,13 @@ lsmod | grep -e ipvs -e nf_conntrack_ipv4
cut -f1 -d " " /proc/modules | grep -e ip_vs -e nf_conntrack_ipv4
```
Packages such as `ipset` should also be installed on the node before using IPVS mode.
Packages such as `ipset` should also be installed on the node before using IPVS mode.
Kube-proxy will fall back to IPTABLES mode if those requirements are not met.
### Local UP Cluster
Kube-proxy will run in iptables mode by default in a [local-up cluster](https://github.com/kubernetes/community/blob/master/contributors/devel/running-locally.md).
Kube-proxy will run in iptables mode by default in a [local-up cluster](https://github.com/kubernetes/community/blob/master/contributors/devel/running-locally.md).
To use IPVS mode, users should export the env `KUBE_PROXY_MODE=ipvs` to specify the ipvs mode before [starting the cluster](https://github.com/kubernetes/community/blob/master/contributors/devel/running-locally.md#starting-the-cluster):
```shell
@ -275,7 +334,7 @@ export KUBE_PROXY_MODE=ipvs
### Cluster Created by Kubeadm
Kube-proxy will run in iptables mode by default in a cluster deployed by [kubeadm](https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/).
Kube-proxy will run in iptables mode by default in a cluster deployed by [kubeadm](https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/).
If you are using kubeadm with a [configuration file](https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-init/#config-file), you can specify the ipvs mode adding `SupportIPVSProxyMode: true` below the `kubeProxy` field.
@ -301,7 +360,7 @@ kubeadm init --feature-gates=SupportIPVSProxyMode=true
to specify the ipvs mode before deploying the cluster.
**Notes**
**Notes**
If ipvs mode is successfully on, you should see ipvs proxy rules (use `ipvsadm`) like
```shell
# ipvsadm -ln
@ -316,7 +375,7 @@ or similar logs occur in kube-proxy logs (for example, `/tmp/kube-proxy.log` for
Using ipvs Proxier.
```
While there is no ipvs proxy rules or the following logs ocuurs indicate that the kube-proxy fails to use ipvs mode:
While there is no ipvs proxy rules or the following logs ocuurs indicate that the kube-proxy fails to use ipvs mode:
```
Can't use ipvs proxier, trying iptables proxier
Using iptables Proxier.
@ -352,7 +411,7 @@ UDP 10.0.0.10:53 rr
### Why kube-proxy can't start IPVS mode
Use the following check list to help you solve the problems:
Use the following check list to help you solve the problems:
**1. Enable IPVS feature gateway**