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Diffstat (limited to 'middleware/kubernetes/README.md')
| -rw-r--r-- | middleware/kubernetes/README.md | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/middleware/kubernetes/README.md b/middleware/kubernetes/README.md index 0ae9681d4..024e448db 100644 --- a/middleware/kubernetes/README.md +++ b/middleware/kubernetes/README.md @@ -44,6 +44,13 @@ This is the default kubernetes setup, with everything specified in full: template {service}.{namespace}.{zone} # Only expose the k8s namespace "demo" namespaces demo + # Only expose the records for kubernetes objects + # that matches this label selector. The label + # selector syntax is described in the kubernetes + # API documentation: http://kubernetes.io/docs/user-guide/labels/ + # Example selector below only exposes objects tagged as + # "application=nginx" in the staging or qa environments. + #labels environment in (staging, qa),application=nginx } # Perform DNS response caching for the coredns.local zone # Cache timeout is provided by the integer in seconds @@ -51,10 +58,13 @@ This is the default kubernetes setup, with everything specified in full: } ~~~ -Notes: +Defaults: * If the `namespaces` keyword is omitted, all kubernetes namespaces are exposed. * If the `template` keyword is omitted, the default template of "{service}.{namespace}.{zone}" is used. * If the `resyncperiod` keyword is omitted, the default resync period is 5 minutes. +* The `labels` keyword is only used when filtering of results based on kubernetes label selector syntax + is required. The label selector syntax is described in the kubernetes API documentation at: + http://kubernetes.io/docs/user-guide/labels/ ### Basic Setup @@ -191,7 +201,7 @@ mynginx.demo.coredns.local. 0 IN A 10.0.0.10 ## Implementation Notes/Ideas -### Basic Zone Mapping (implemented) +### Basic Zone Mapping The middleware is configured with a "zone" string. For example: "zone = coredns.local". @@ -200,8 +210,8 @@ to: "myservice.mynamespace.coredns.local". The middleware should publish an A record for that service and a service record. -Initial implementation just performs the above simple mapping. Subsequent -revisions should allow different namespaces to be published under different zones. +If multiple zone names are specified, the records for kubernetes objects are +exposed in all listed zones. For example: @@ -262,11 +272,6 @@ return the IP addresses for all services with "nginx" in the service name. TBD: * How does this relate the the k8s load-balancer configuration? -* Do wildcards search across namespaces? (Yes) -* Initial implementation assumes that a namespace maps to the first DNS label - below the zone managed by the kubernetes middleware. This assumption may - need to be revised. (Template scheme for record names removes this assumption.) - ## TODO * SkyDNS compatibility/equivalency: @@ -318,19 +323,19 @@ TBD: * Additional features: * Reverse IN-ADDR entries for services. (Is there any value in supporting reverse lookup records?) (need tests, functionality should work based on @aledbf's code.) - * How to support label specification in Corefile to allow use of labels to - indicate zone? (Is this even useful?) For example, the following + * (done) ~~How to support label specification in Corefile to allow use of labels to + indicate zone? For example, the following configuration exposes all services labeled for the "staging" environment and tenant "customerB" in the zone "customerB.stage.local": kubernetes customerB.stage.local { # Use url for k8s API endpoint endpoint http://localhost:8080 - label "environment" : "staging", "tenant" : "customerB" + labels environment in (staging),tenant=customerB } Note: label specification/selection is a killer feature for segmenting - test vs staging vs prod environments. + test vs staging vs prod environments.~~ Need label testing. * Implement IP selection and ordering (internal/external). Related to wildcards and SkyDNS use of CNAMES. * Flatten service and namespace names to valid DNS characters. (service names |