Inspired by HashiCorp's Consul Template, kube-template is a utility that queries a Kubernetes API server and uses its objects as input data for specified set of templates. Also it can run arbitrary commands for templates with updated output.
Please note this is a work in progress.
Go 1.13+ is required to build kube-template. Check your version with go version before build.
git pull https://github.com/3cky/kube-template.gitcd kube-templatemake install
Docker
If you want to create a Docker image
- adjust Dockerfile in contrib/docker directory to fit your needs
- configure settings files in contrib/docker/conf directory
- issue
make docker
Note - the built image is already configured to automatically locate Kubernetes API along with everything is needed to connect (e.g. Certificate Authority file, security token and so on).
--alsologtostderr log to standard error as well as files
--command-timeout duration Default command execution timeout (0 to execute commands without timeout checking) (default 15s)
-c, --config string config file (default is ./kube-template.(yaml|json))
--dry-run don't write template output, dump result to stdout
--guess-kube-api-settings guess Kubernetes API settings from POD environment
--help-md get help in Markdown format
-k, --kube-config string Kubernetes config file to use
-l, --left-delimiter string templating left delimiter (default "{{")
--log-backtrace-at traceLocation when logging hits line file:N, emit a stack trace (default :0)
--log-dir string If non-empty, write log files in this directory
--log-flush-frequency duration Maximum number of seconds between log flushes (default 5s)
--logtostderr log to standard error instead of files (default true)
--master string Kubernetes API server address (default is http://127.0.0.1:8080/)
--once run template processing once and exit
-p, --poll-period duration Kubernetes API server poll period (0 disables server polling) (default 15s)
-r, --right-delimiter string templating right delimiter (default "}}")
--stderrthreshold severity logs at or above this threshold go to stderr (default 2)
-t, --template stringSlice adds a new template to watch on disk in the format
'templatePath:outputPath[:command]'. This option is additive
and may be specified multiple times for multiple templates
-v, --v Level log level for V logs
--version display the version number and build timestamp
--vmodule moduleSpec comma-separated list of pattern=N settings for file-filtered logging
Process single template using data from remote Kubernetes API server and exit:
$ kube-template \
--master="http://kube-api.server.com:8080" \
--template="/tmp/input.tmpl:/tmp/output.txt" \
--once Monitor local Kubernetes API server for updates every 30 seconds and update nginx and haproxy configuration files with reload:
$ kube-template \
--template="/tmp/nginx.tmpl:/etc/nginx/nginx.conf:service nginx reload" \
--template="/tmp/haproxy.tmpl:/etc/haproxy/haproxy.conf:service haproxy reload" \
--poll-time=30skube-template looks for kube-template.json or kube-template.yaml configuration file in current working directory or file name specified by --config command line option.
YAML configuration file example:
master: http://localhost:8080
poll-period: 10s
command-timeout: 30s
templates:
- path: in.txt.tmpl
output: out.txt
command: action.sh
command-timeout: 60s
- path: in.html.tmpl
output: out.htmlPlease note: templates specified on the command line take precedence over those defined in a config file.
- TERM, QUIT, INT: graceful shutdown
- HUP: reload configuration file
kube-template works with templates in the Go Template format. In addition to the standard template functions, kube-template provides the following functions:
{{pods "selector" "namespace"}}
Query Kubernetes API server for pods from given namespace (default if not specified) matching given selector (empty to get all pods).
Example:
{{range pods}}
{{.Name}}: {{.Status.Phase}}
{{end}}
{{services "selector" "namespace"}}
Query Kubernetes API server for services from given namespace (default if not specified) matching given selector (empty to get all services).
{{replicationcontrollers "selector" "namespace"}}
Query Kubernetes API server for replication controllers from given namespace (default if not specified) matching given selector (empty to get all replication controllers).
{{events "selector" "namespace"}}
Query Kubernetes API server for events from given namespace (default if not specified) matching given selector (empty to get all events).
{{endpoints "selector" "namespace"}}
Query Kubernetes API server for endpoints from given namespace (default if not specified) matching given selector (empty to get all endpoints).
{{nodes "selector"}}
Query Kubernetes API server for nodes matching given selector (empty to get all nodes).
{{namespaces "selector"}}
Query Kubernetes API server for namespaces matching given selector (empty to get all namespaces).
{{componentstatuses "selector"}}
Query Kubernetes API server for component statuses matching given selector (empty to get all componentstatuses).
{{configmaps "selector" "namespace"}}
Query Kubernetes API server for config maps from given namespace (default if not specified) matching given selector (empty to get all configmaps).
{{limitranges "selector" "namespace"}}
Query Kubernetes API server for limit ranges from given namespace (default if not specified) matching given selector (empty to get all limitranges).
{{persistentvolumes "selector"}}
Query Kubernetes API server for persistent volumes matching given selector (empty to get all persistentvolumes).
{{persistentvolumeclaims "selector" "namespace"}}
Query Kubernetes API server for persistent volume claims from given namespace (default if not specified) matching given selector (empty to get all persistentvolumeclaims).
{{podtemplates "selector" "namespace"}}
Query Kubernetes API server for pod templates from given namespace (default if not specified) matching given selector (empty to get all podtemplates).
{{resourcequotas "selector" "namespace"}}
Query Kubernetes API server for resource quotas from given namespace (default if not specified) matching given selector (empty to get all resourcequotas).
{{secrets "selector" "namespace"}}
Query Kubernetes API server for secrets from given namespace (default if not specified) matching given selector (empty to get all secrets).
{{serviceaccounts "selector" "namespace"}}
Query Kubernetes API server for service accounts from given namespace (default if not specified) matching given selector (empty to get all serviceaccounts).
All Sprig library template functions (string/math/date/etc) are supported (thanks @bpineau).
Populate nginx upstream with pods labeled 'name=test-pod':
upstream test-pod-upstream {
{{with $pods := pods "name=test-pod"}}
ip_hash;
{{range $pods}}
server {{.Status.PodIP}}:8080;
{{end}}
{{else}}
# No pods with given label were found, use stub server
server 127.0.0.1:8081;
{{end}}
}
Create haproxy TCP balancer for pods listening on container port 9000:
{{with $pods := pods "name=test-pod"}}
{{$maxconn := 1000}}
listen test-pod-balancer
bind *:9000
mode tcp
maxconn {{mul $maxconn (len $pods)}}
balance roundrobin
{{range $pods}}
server {{.Name}} {{.Status.PodIP}}:9000 maxconn {{$maxconn}} check inter 5000 rise 3 fall 3
{{end}}
server stub 127.0.0.1:7690 backup
{{end}}
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request
kube-template is released under the Apache 2.0 license. See LICENSE.txt