Network policy

A network policy resource (NetworkPolicy) represents an ordered set of rules which are applied to a collection of endpoints that match a label selector.

NetworkPolicy is a namespaced resource. NetworkPolicy in a specific namespace only applies to workload endpoint resources in that namespace. Two resources are in the same namespace if the namespace value is set the same on both. See global network policy resource for non-namespaced network policy.

NetworkPolicy resources can be used to define network connectivity rules between groups of Calico endpoints and host endpoints, and take precedence over profile resources if any are defined.

Sample YAML

This sample policy allows TCP traffic from frontend endpoints to port 6379 on database endpoints.

  1. apiVersion: projectcalico.org/v3
  2. kind: NetworkPolicy
  3. metadata:
  4. name: allow-tcp-6379
  5. namespace: production
  6. spec:
  7. selector: role == 'database'
  8. types:
  9. - Ingress
  10. - Egress
  11. ingress:
  12. - action: Allow
  13. metadata:
  14. annotations:
  15. from: frontend
  16. to: database
  17. protocol: TCP
  18. source:
  19. selector: role == 'frontend'
  20. destination:
  21. ports:
  22. - 6379
  23. egress:
  24. - action: Allow

Definition

Metadata

FieldDescriptionAccepted ValuesSchemaDefault
nameThe name of the network policy. Required.Alphanumeric string with optional ., _, or -.string
namespaceNamespace provides an additional qualification to a resource name.string“default”

Spec

FieldDescriptionAccepted ValuesSchemaDefault
orderControls the order of precedence. Calico applies the policy with the lowest value first.float
selectorSelects the endpoints to which this policy applies.selectorall()
typesApplies the policy based on the direction of the traffic. To apply the policy to inbound traffic, set to Ingress. To apply the policy to outbound traffic, set to Egress. To apply the policy to both, set to Ingress, Egress.Ingress, EgressList of stringsDepends on presence of ingress/egress rules*
ingressOrdered list of ingress rules applied by policy.List of Rule
egressOrdered list of egress rules applied by this policy.List of Rule
serviceAccountSelectorSelects the service account(s) to which this policy applies. Select a specific service account by name using the projectcalico.org/name label.selectorall()

* If types has no value, Calico defaults as follows.

Ingress Rules PresentEgress Rules PresentTypes value
NoNoIngress
YesNoIngress
NoYesEgress
YesYesIngress, Egress

Rule

A single rule matches a set of packets and applies some action to them. When multiple rules are specified, they are executed in order.

FieldDescriptionAccepted ValuesSchemaDefault
metadataPer-rule metadata.RuleMetadata
actionAction to perform when matching this rule.Allow, Deny, Log, Passstring
protocolPositive protocol match.TCP, UDP, ICMP, ICMPv6, SCTP, UDPLite, 1-255string | integer
notProtocolNegative protocol match.TCP, UDP, ICMP, ICMPv6, SCTP, UDPLite, 1-255string | integer
icmpICMP match criteria.ICMP
notICMPNegative match on ICMP.ICMP
ipVersionPositive IP version match.4, 6integer
sourceSource match parameters.EntityRule
destinationDestination match parameters.EntityRule
httpMatch HTTP request parameters. Application layer policy must be enabled to use this field.HTTPMatch

After a Log action, processing continues with the next rule; Allow and Deny are immediate and final and no further rules are processed.

An action of Pass in a NetworkPolicy or GlobalNetworkPolicy will skip over the remaining policies and jump to the first profile assigned to the endpoint, applying the policy configured in the profile; if there are no Profiles configured for the endpoint the default applied action is Deny.

RuleMetadata

Metadata associated with a specific rule (rather than the policy as a whole). The contents of the metadata does not affect how a rule is interpreted or enforced; it is simply a way to store additional information for use by operators or applications that interact with Calico.

FieldDescriptionSchemaDefault
annotationsArbitrary non-identifying metadata.map of string to string

Example:

  1. metadata:
  2. annotations:
  3. app: database
  4. owner: devops

Annotations follow the same rules as Kubernetes for valid syntax and character set.

On Linux with the iptables dataplane, rule annotations are rendered as comments in the form -m comment --comment "<key>=<value>" on the iptables rule(s) that correspond to the Calico rule.

ICMP

FieldDescriptionAccepted ValuesSchemaDefault
typeMatch on ICMP type.Can be integer 0-254integer
codeMatch on ICMP code.Can be integer 0-255integer

EntityRule

Entity rules specify the attributes of the source or destination of a packet that must match for the rule as a whole to match. Packets are matched on their IPs and ports. If the rule contains multiple match criteria (for example, an IP and a port) then all match criteria must match for the rule as a whole to match.

Selectors offer a powerful way to select the source or destination to match based on labels. Selectors can match workload endpoints, host endpoint and (namespaced or global) network sets.

FieldDescriptionAccepted ValuesSchemaDefault
netsMatch packets with IP in any of the listed CIDRs.List of valid IPv4 CIDRs or list of valid IPv6 CIDRs (IPv4 and IPv6 CIDRs shouldn’t be mixed in one rule)list of cidrs
notNetsNegative match on CIDRs. Match packets with IP not in any of the listed CIDRs.List of valid IPv4 CIDRs or list of valid IPv6 CIDRs (IPv4 and IPv6 CIDRs shouldn’t be mixed in one rule)list of cidrs
selectorPositive match on selected endpoints. If a namespaceSelector is also defined, the set of endpoints this applies to is limited to the endpoints in the selected namespaces.Valid selectorselector
notSelectorNegative match on selected endpoints. If a namespaceSelector is also defined, the set of endpoints this applies to is limited to the endpoints in the selected namespaces.Valid selectorselector
namespaceSelectorPositive match on selected namespaces. If specified, only workload endpoints in the selected Kubernetes namespaces are matched. Matches namespaces based on the labels that have been applied to the namespaces. Defines the scope that selectors will apply to, if not defined then selectors apply to the NetworkPolicy’s namespace. Match a specific namespace by name using the projectcalico.org/name label. Select the non-namespaced resources like GlobalNetworkSet(s), host endpoints to which this policy applies by using global() selector.Valid selectorselector
portsPositive match on the specified portslist of ports
notPortsNegative match on the specified portslist of ports
serviceAccountsMatch endpoints running under service accounts. If a namespaceSelector is also defined, the set of service accounts this applies to is limited to the service accounts in the selected namespaces.ServiceAccountMatch
servicesMatch the specified service(s). If specified on egress rule destinations, no other selection criteria can be set. If specified on ingress rule sources, only positive or negative matches on ports can be specified.ServiceMatch

When using selectors in network policy, remember that selectors only match (known) resources, but rules match packets. A rule with a selector all() won’t match “all packets”, it will match “packets from all in-scope endpoints and network sets”. To match all packets, do not include a selector in the rule at all.

Network policy - 图1note

notSelector is somewhat subtle because the not in notSelector negates the packet match rather than the selector:

  • selector: !has(foo) matches packets from/to endpoints and network sets that do not have the label “foo”.
  • notSelector: has(foo) matches packets from/to anywhere (including outside the cluster), except traffic from/to endpoints and network sets that have the label “foo”.

Selectors

A label selector is an expression which either matches or does not match a resource based on its labels.

Calico label selectors support a number of operators, which can be combined into larger expressions using the boolean operators and parentheses.

ExpressionMeaning
Logical operators
( <expression> )Matches if and only if <expression> matches. (Parentheses are used for grouping expressions.)
! <expression>Matches if and only if <expression> does not match. Tip: ! is a special character at the start of a YAML string, if you need to use ! at the start of a YAML string, enclose the string in quotes.
<expression 1> && <expression 2>“And”: matches if and only if both <expression 1>, and, <expression 2> matches
<expression 1> || <expression 2>“Or”: matches if and only if either <expression 1>, or, <expression 2> matches.
Match operators
all()Match all in-scope resources. To match no resources, combine this operator with ! to form !all().
global()Match all non-namespaced resources. Useful in a namespaceSelector to select global resources such as global network sets.
k == ‘v’Matches resources with the label ‘k’ and value ‘v’.
k != ‘v’Matches resources without label ‘k’ or with label ‘k’ and value not equal to v
has(k)Matches resources with label ‘k’, independent of value. To match pods that do not have label k, combine this operator with ! to form !has(k)
k in { ‘v1’, ‘v2’ }Matches resources with label ‘k’ and value in the given set
k not in { ‘v1’, ‘v2’ }Matches resources without label ‘k’ or with label ‘k’ and value not in the given set
k contains ‘s’Matches resources with label ‘k’ and value containing the substring ‘s’
k starts with ‘s’Matches resources with label ‘k’ and value starting with the substring ‘s’
k ends with ‘s’Matches resources with label ‘k’ and value ending with the substring ‘s’

Operators have the following precedence:

  • Highest: all the match operators
  • Parentheses ( ... )
  • Negation with !
  • Conjunction with &&
  • Lowest: Disjunction with ||

For example, the expression

  1. ! has(my-label) || my-label starts with 'prod' && role in {'frontend','business'}

Would be “bracketed” like this:

  1. ((!(has(my-label)) || ((my-label starts with 'prod') && (role in {'frontend','business'}))

It would match:

  • Any resource that did not have label “my-label”.
  • Any resource that both:
    • Has a value for my-label that starts with “prod”, and,
    • Has a role label with value either “frontend”, or “business”.

Understanding scopes and the all() and global() operators: selectors have a scope of resources that they are matched against, which depends on the context in which they are used. For example:

  • The nodeSelector in an IPPool selects over Node resources.

  • The top-level selector in a NetworkPolicy selects over the workloads in the same namespace as the NetworkPolicy.

  • The top-level selector in a GlobalNetworkPolicy doesn’t have the same restriction, it selects over all endpoints including namespaced WorkloadEndpoints and non-namespaced HostEndpoints.

  • The namespaceSelector in a NetworkPolicy (or GlobalNetworkPolicy) rule selects over the labels on namespaces rather than workloads.

  • The namespaceSelector determines the scope of the accompanying selector in the entity rule. If no namespaceSelector is present then the rule’s selector matches the default scope for that type of policy. (This is the same namespace for NetworkPolicy and all endpoints/network sets for GlobalNetworkPolicy)

  • The global() operator can be used (only) in a namespaceSelector to change the scope of the main selector to include non-namespaced resources such as GlobalNetworkSet. This allows namespaced NetworkPolicy resources to refer to global non-namespaced resources, which would otherwise be impossible.

Ports

Calico supports the following syntaxes for expressing ports.

SyntaxExampleDescription
int80The exact (numeric) port specified
start:end6040:6050All (numeric) ports within the range start <= x <= end
stringnamed-portA named port, as defined in the ports list of one or more endpoints

An individual numeric port may be specified as a YAML/JSON integer. A port range or named port must be represented as as a string. For example, this would be a valid list of ports:

  1. ports: [8080, '1234:5678', 'named-port']

Named ports

Using a named port in an EntityRule, instead of a numeric port, gives a layer of indirection, allowing for the named port to map to different numeric values for each endpoint.

For example, suppose you have multiple HTTP servers running as workloads; some exposing their HTTP port on port 80 and others on port 8080. In each workload, you could create a named port called http-port that maps to the correct local port. Then, in a rule, you could refer to the name http-port instead of writing a different rule for each type of server.

Network policy - 图2note

Since each named port may refer to many endpoints (and Calico has to expand a named port into a set of endpoint/port combinations), using a named port is considerably more expensive in terms of CPU than using a simple numeric port. We recommend that they are used sparingly, only where the extra indirection is required.

ServiceAccountMatch

A ServiceAccountMatch matches service accounts in an EntityRule.

FieldDescriptionSchema
namesMatch service accounts by namelist of strings
selectorMatch service accounts by labelselector

ServiceMatch

A ServiceMatch matches a service in an EntityRule.

FieldDescriptionSchema
nameThe service’s name.string
namespaceThe service’s namespace.string

Application layer policy

Application layer policy is an optional feature of Calico and must be enabled in order to use the following match criteria.

Network policy - 图3note

Application layer policy match criteria are supported with the following restrictions.

  • Only ingress policy is supported. Egress policy must not contain any application layer policy match clauses.
  • Rules must have the action Allow if they contain application layer policy match clauses.

HTTPMatch

An HTTPMatch matches attributes of an HTTP request. The presence of an HTTPMatch clause on a Rule will cause that rule to only match HTTP traffic. Other application layer protocols will not match the rule.

Example:

  1. http:
  2. methods: ['GET', 'PUT']
  3. paths:
  4. - exact: '/projects/calico'
  5. - prefix: '/users'
FieldDescriptionSchema
methodsMatch HTTP methods. Case sensitive. Standard HTTP method descriptions.list of strings
pathsMatch HTTP paths. Case sensitive.list of HTTPPathMatch

HTTPPathMatch

SyntaxExampleDescription
exactexact: “/foo/bar”Matches the exact path as written, not including the query string or fragments.
prefixprefix: “/keys”Matches any path that begins with the given prefix.

Supported operations

Datastore typeCreate/DeleteUpdateGet/ListNotes
etcdv3YesYesYes
Kubernetes API datastoreYesYesYes