Document new check_restart stanza
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Michael Schurter
parent
99f4aa999a
commit
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@ -66,7 +66,12 @@ Below is the JSON representation of the job outputed by `$ nomad init`:
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"Interval": 10000000000,
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"Timeout": 2000000000,
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"InitialStatus": "",
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"TLSSkipVerify": false
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"TLSSkipVerify": false,
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"CheckRestart": {
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"Limit": 3,
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"Grace": "30s",
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"IgnoreWarnings": false
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}
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}]
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}],
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"Resources": {
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@ -377,6 +382,20 @@ The `Task` object supports the following keys:
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- `TLSSkipVerify`: If true, Consul will not attempt to verify the
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certificate when performing HTTPS checks. Requires Consul >= 0.7.2.
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- `CheckRestart`: `CheckRestart` is an object which enables
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restarting of tasks based upon Consul health checks.
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- `Limit`: The number of unhealthy checks allowed before the
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service is restarted. Defaults to `0` which disables
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health-based restarts.
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- `Grace`: The duration to wait after a task starts or restarts
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before counting unhealthy checks count against the limit.
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Defaults to "1s".
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- `IgnoreWarnings`: Treat checks that are warning as passing.
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Defaults to false which means warnings are considered unhealthy.
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- `ShutdownDelay` - Specifies the duration to wait when killing a task between
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removing it from Consul and sending it a shutdown signal. Ideally services
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would fail healthchecks once they receive a shutdown signal. Alternatively
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@ -47,6 +47,12 @@ job "docs" {
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args = ["--verbose"]
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interval = "60s"
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timeout = "5s"
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check_restart {
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limit = 3
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grace = "90s"
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ignore_warnings = false
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}
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}
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}
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}
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@ -162,6 +168,72 @@ scripts.
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- `tls_skip_verify` `(bool: false)` - Skip verifying TLS certificates for HTTPS
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checks. Requires Consul >= 0.7.2.
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#### `check_restart` Stanza
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As of Nomad 0.7 `check` stanzas may include a `check_restart` stanza to restart
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tasks with unhealthy checks. Restarts use the parameters from the
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[`restart`][restart_stanza] stanza, so if a task group has the default `15s`
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delay, tasks won't be restarted for an extra 15 seconds after the
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`check_restart` block considers it failed. `check_restart` stanzas have the
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follow parameters:
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- `limit` `(int: 0)` - Restart task after `limit` failing health checks. For
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example 1 causes a restart on the first failure. The default, `0`, disables
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healtcheck based restarts. Failures must be consecutive. A single passing
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check will reset the count, so flapping services may not be restarted.
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- `grace` `(string: "1s")` - Duration to wait after a task starts or restarts
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before checking its health. On restarts the `delay` and max jitter is added
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to the grace period to prevent checking a task's health before it has
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restarted.
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- `ignore_warnings` `(bool: false)` - By default checks with both `critical`
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and `warning` statuses are considered unhealthy. Setting `ignore_warnings =
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true` treats a `warning` status like `passing` and will not trigger a restart.
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For example:
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```hcl
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restart {
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delay = "8s"
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}
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task "mysqld" {
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service {
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# ...
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check {
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type = "script"
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name = "check_table"
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command = "/usr/local/bin/check_mysql_table_status"
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args = ["--verbose"]
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interval = "20s"
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timeout = "5s"
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check_restart {
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# Restart the task after 3 consecutive failed checks (180s)
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limit = 3
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# Ignore failed checks for 90s after a service starts or restarts
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grace = "90s"
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# Treat warnings as unhealthy (the default)
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ignore_warnings = false
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}
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}
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}
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}
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```
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In this example the `mysqld` task has `90s` from startup to begin passing
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healthchecks. After the grace period if `mysqld` would remain unhealthy for
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`60s` (as determined by `limit * interval`) it would be restarted after `8s`
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(as determined by the `restart.delay`). Nomad would then wait `100s` (as
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determined by `grace + delay + (delay * 0.25)`) before checking `mysqld`'s
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health again.
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~> `check_restart` stanzas may also be placed in `service` stanzas to apply the
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same restart logic to multiple checks.
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#### `header` Stanza
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HTTP checks may include a `header` stanza to set HTTP headers. The `header`
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@ -170,6 +242,7 @@ the header to be set multiple times, once for each value.
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```hcl
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service {
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# ...
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check {
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type = "http"
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port = "lb"
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@ -319,3 +392,4 @@ system of a task for that driver.</small>
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[interpolation]: /docs/runtime/interpolation.html "Nomad Runtime Interpolation"
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[network]: /docs/job-specification/network.html "Nomad network Job Specification"
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[qemu]: /docs/drivers/qemu.html "Nomad qemu Driver"
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[restart_stanza]: /docs/job-specification/restart.html "restart stanza"
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