1OC(1) June 2016 OC(1)
2
6 oc observe - Observe changes to resources and react to them (experimen‐
7 tal)
8
12 oc observe [OPTIONS]
13
17 Observe changes to resources and take action on them
18 This command assists in building scripted reactions to changes that
21 occur in Kubernetes or OpenShift resources. This is frequently referred
22 to as a 'controller' in Kubernetes and acts to ensure particular condi‐
23 tions are maintained. On startup, observe will list all of the
24 resources of a particular type and execute the provided script on each
25 one. Observe watches the server for changes, and will reexecute the
26 script for each update.
27 Observe works best for problems of the form "for every resource X, make
30 sure Y is true". Some examples of ways observe can be used include:
31 · Ensure every namespace has a quota or limit range object
33 · Ensure every service is registered in DNS by making calls to a
35 DNS API
36 · Send an email alert whenever a node reports 'NotReady'
38 · Watch for the 'FailedScheduling' event and write an IRC mes‐
40 sage
41 · Dynamically provision persistent volumes when a new PVC is
43 created
44 · Delete pods that have reached successful completion after a
46 period of time.
47 The simplest pattern is maintaining an invariant on an object - for
49 instance, "every namespace should have an annotation that indicates its
50 owner". If the object is deleted no reaction is necessary. A variation
51 on that pattern is creating another object: "every namespace should
52 have a quota object based on the resources allowed for an owner".
53 $ cat set_owner.sh
56 #!/bin/sh
57 if [[ "$(oc get namespace "$1" --template='{{ .metadata.annota‐
58 tions.owner }}')" == "" ]]; then
59 oc annotate namespace "$1" owner=bob
60 fi
61 $ oc observe namespaces -- ./set_owner.sh
64 The set _owner.sh script is invoked with a single argument (the names‐
67 pace name) for each namespace. This simple script ensures that any user
68 without the "owner" annotation gets one set, but preserves any existing
69 value.
70 The next common of controller pattern is provisioning - making changes
73 in an external system to match the state of a Kubernetes resource.
74 These scripts need to account for deletions that may take place while
75 the observe command is not running. You can provide the list of known
76 objects via the --names command, which should return a newline-delim‐
77 ited list of names or namespace/name pairs. Your command will be
78 invoked whenever observe checks the latest state on the server - any
79 resources returned by --names that are not found on the server will be
80 passed to your --delete command.
81 For example, you may wish to ensure that every node that is added to
84 Kubernetes is added to your cluster inventory along with its IP:
85 $ cat add_to_inventory.sh
88 #!/bin/sh
89 echo "$1 $2" >> inventory
90 sort -u inventory -o inventory
91 $ cat remove_from_inventory.sh
94 #!/bin/sh
95 grep -vE "^$1 " inventory > /tmp/newinventory
96 mv -f /tmp/newinventory inventory
97 $ cat known_nodes.sh
100 #!/bin/sh
101 touch inventory
102 cut -f 1-1 -d ' ' inventory
103 $ oc observe nodes -a '{ .status.addresses[0].address }' \
106 --names ./known_nodes.sh \
107 --delete ./remove_from_inventory.sh \
108 -- ./add_to_inventory.sh
109 If you stop the observe command and then delete a node, when you launch
112 observe again the contents of inventory will be compared to the list of
113 nodes from the server, and any node in the inventory file that no
114 longer exists will trigger a call to remove from inventory.sh with the
115 name of the node.
116 Important: when handling deletes, the previous state of the object may
119 not be available and only the name/namespace of the object will be
120 passed to your --delete command as arguments (all custom arguments
121 are omitted).
122 More complicated interactions build on the two examples above - your
125 inventory script could make a call to allocate storage on your infra‐
126 structure as a service, or register node names in DNS, or set complex
127 firewalls. The more complex your integration, the more important it is
128 to record enough data in the remote system that you can identify when
129 resources on either side are deleted.
130
134 --all-namespaces=false
135 If true, list the requested object(s) across all projects. Project
136 in current context is ignored.
137 -a, --argument=""
140 Template for the arguments to be passed to each command in the for‐
141 mat defined by --output.
142 -d, --delete=""
145 A command to run when resources are deleted. Specify multiple times
146 to add arguments.
147 --exit-after=0
150 Exit with status code 0 after the provided duration, optional.
151 --listen-addr=":11251"
154 The name of an interface to listen on to expose metrics and health
155 checking.
156 --maximum-errors=20
159 Exit after this many errors have been detected with. May be set to
160 -1 for no maximum.
161 --names=""
164 A command that will list all of the currently known names,
165 optional. Specify multiple times to add arguments. Use to get notifica‐
166 tions when objects are deleted.
167 --no-headers=false
170 If true, skip printing information about each event prior to exe‐
171 cuting the command.
172 --object-env-var=""
175 The name of an env var to serialize the object to when calling the
176 command, optional.
177 --once=false
180 If true, exit with a status code 0 after all current objects have
181 been processed.
182 --output="jsonpath"
185 Controls the template type used for the --argument flags. Supported
186 values are gotemplate and jsonpath.
187 --print-metrics-on-exit=false
190 If true, on exit write all metrics to stdout.
191 --resync-period=0
194 When non-zero, periodically reprocess every item from the server as
195 a Sync event. Use to ensure external systems are kept up to date.
196 --retry-count=2
199 The number of times to retry a failing command before continuing.
200 --retry-on-exit-code=0
203 If any command returns this exit code, retry up to --retry-count
204 times.
205 --strict-templates=false
208 If true return an error on any field or map key that is not missing
209 in a template.
210 --type-env-var=""
213 The name of an env var to set with the type of event received
214 ('Sync', 'Updated', 'Deleted', 'Added') to the reaction command or
215 --delete.
216
220 --allow_verification_with_non_compliant_keys=false
221 Allow a SignatureVerifier to use keys which are technically
222 non-compliant with RFC6962.
223 --alsologtostderr=false
226 log to standard error as well as files
227 --application_metrics_count_limit=100
230 Max number of application metrics to store (per container)
231 --as=""
234 Username to impersonate for the operation
235 --as-group=[]
238 Group to impersonate for the operation, this flag can be repeated
239 to specify multiple groups.
240 --azure-container-registry-config=""
243 Path to the file containing Azure container registry configuration
244 information.
245 --boot_id_file="/proc/sys/kernel/random/boot_id"
248 Comma-separated list of files to check for boot-id. Use the first
249 one that exists.
250 --cache-dir="/builddir/.kube/http-cache"
253 Default HTTP cache directory
254 --certificate-authority=""
257 Path to a cert file for the certificate authority
258 --client-certificate=""
261 Path to a client certificate file for TLS
262 --client-key=""
265 Path to a client key file for TLS
266 --cloud-provider-gce-lb-src-cidrs=130.211.0.0/22,209.85.152.0/22,209.85.204.0/22,35.191.0.0/16
269 CIDRs opened in GCE firewall for LB traffic proxy health checks
270 --cluster=""
273 The name of the kubeconfig cluster to use
274 --container_hints="/etc/cadvisor/container_hints.json"
277 location of the container hints file
278 --containerd="unix:///var/run/containerd.sock"
281 containerd endpoint
282 --context=""
285 The name of the kubeconfig context to use
286 --default-not-ready-toleration-seconds=300
289 Indicates the tolerationSeconds of the toleration for
290 notReady:NoExecute that is added by default to every pod that does not
291 already have such a toleration.
292 --default-unreachable-toleration-seconds=300
295 Indicates the tolerationSeconds of the toleration for unreach‐
296 able:NoExecute that is added by default to every pod that does not
297 already have such a toleration.
298 --docker="unix:///var/run/docker.sock"
301 docker endpoint
302 --docker-tls=false
305 use TLS to connect to docker
306 --docker-tls-ca="ca.pem"
309 path to trusted CA
310 --docker-tls-cert="cert.pem"
313 path to client certificate
314 --docker-tls-key="key.pem"
317 path to private key
318 --docker_env_metadata_whitelist=""
321 a comma-separated list of environment variable keys that needs to
322 be collected for docker containers
323 --docker_only=false
326 Only report docker containers in addition to root stats
327 --docker_root="/var/lib/docker"
330 DEPRECATED: docker root is read from docker info (this is a fall‐
331 back, default: /var/lib/docker)
332 --enable_load_reader=false
335 Whether to enable cpu load reader
336 --event_storage_age_limit="default=24h"
339 Max length of time for which to store events (per type). Value is a
340 comma separated list of key values, where the keys are event types
341 (e.g.: creation, oom) or "default" and the value is a duration. Default
342 is applied to all non-specified event types
343 --event_storage_event_limit="default=100000"
346 Max number of events to store (per type). Value is a comma sepa‐
347 rated list of key values, where the keys are event types (e.g.: cre‐
348 ation, oom) or "default" and the value is an integer. Default is
349 applied to all non-specified event types
350 --global_housekeeping_interval=0
353 Interval between global housekeepings
354 --housekeeping_interval=0
357 Interval between container housekeepings
358 --insecure-skip-tls-verify=false
361 If true, the server's certificate will not be checked for validity.
362 This will make your HTTPS connections insecure
363 --kubeconfig=""
366 Path to the kubeconfig file to use for CLI requests.
367 --log-flush-frequency=0
370 Maximum number of seconds between log flushes
371 --log_backtrace_at=:0
374 when logging hits line file:N, emit a stack trace
375 --log_cadvisor_usage=false
378 Whether to log the usage of the cAdvisor container
379 --log_dir=""
382 If non-empty, write log files in this directory
383 --logtostderr=true
386 log to standard error instead of files
387 --machine_id_file="/etc/machine-id,/var/lib/dbus/machine-id"
390 Comma-separated list of files to check for machine-id. Use the
391 first one that exists.
392 --match-server-version=false
395 Require server version to match client version
396 -n, --namespace=""
399 If present, the namespace scope for this CLI request
400 --request-timeout="0"
403 The length of time to wait before giving up on a single server
404 request. Non-zero values should contain a corresponding time unit (e.g.
405 1s, 2m, 3h). A value of zero means don't timeout requests.
406 -s, --server=""
409 The address and port of the Kubernetes API server
410 --stderrthreshold=2
413 logs at or above this threshold go to stderr
414 --storage_driver_buffer_duration=0
417 Writes in the storage driver will be buffered for this duration,
418 and committed to the non memory backends as a single transaction
419 --storage_driver_db="cadvisor"
422 database name
423 --storage_driver_host="localhost:8086"
426 database host:port
427 --storage_driver_password="root"
430 database password
431 --storage_driver_secure=false
434 use secure connection with database
435 --storage_driver_table="stats"
438 table name
439 --storage_driver_user="root"
442 database username
443 --token=""
446 Bearer token for authentication to the API server
447 --user=""
450 The name of the kubeconfig user to use
451 -v, --v=0
454 log level for V logs
455 --version=false
458 Print version information and quit
459 --vmodule=
462 comma-separated list of pattern=N settings for file-filtered log‐
463 ging
464
468 # Observe changes to services
469 oc observe services
470 # Observe changes to services, including the clusterIP and invoke a script for each
472 oc observe services -a '{ .spec.clusterIP }' -- register_dns.sh
473
478 oc(1),
479
483 June 2016, Ported from the Kubernetes man-doc generator
484Openshift Openshift CLI User Manuals OC(1)