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* action page * change all page_title fields * update title * constraint through migrate pages * update page title and heading to use sentence case * fix front matter description * Apply suggestions from code review Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com> --------- Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com>
133 lines
3.7 KiB
Plaintext
133 lines
3.7 KiB
Plaintext
---
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layout: docs
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page_title: action block in the job specification
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description: |-
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Configure custom commands in the `action` block of the Nomad job specification. Operators may execute these commands on a running allocation as a controlled way to interact with tasks. Review examples that use actions with arguments and templates.
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---
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# `action` block in the job specification
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<Placement groups={['job', 'group', 'task', 'action']} />
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The `action` block allows job authors to define custom commands. These commands
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can be executed by operators with the necessary permissions on a running
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allocation, offering a controlled way to interact with tasks.
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The name of the action can contain alphanumeric characters and dashes. This
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name must be unique within its task and must not exceed 128 characters.
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## `action` Parameters
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- `command` `(string: <required>)` - Specifies the command to be executed.
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- `args` `(array<string>: [])` - Provides a list of arguments to pass to the command.
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```hcl
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job "my-job" {
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group "my-group" {
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task "my-task" {
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action "get-changelog" {
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command = "/usr/bin/curl"
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args = [
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"-s",
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"https://raw.githubusercontent.com/hashicorp/nomad/main/CHANGELOG.md"
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]
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}
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# ...
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}
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}
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}
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```
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## `action` Examples
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### Basic Action
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This example demonstrates a simple action that prints the current date and time:
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```hcl
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job "example" {
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# ...
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group "demo" {
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# ...
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task "show-date" {
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# ...
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action "current-date" {
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command = "/bin/date"
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}
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}
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}
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}
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```
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### Action with Arguments
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Here, an action uses arguments to perform a specific task:
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```hcl
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job "example" {
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# ...
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group "demo" {
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# ...
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task "list-files" {
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# ...
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action "list-tmp" {
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command = "/bin/ls"
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args = ["-l", "/tmp"]
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}
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}
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}
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}
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```
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### Action with Template
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This advanced example demonstrates an action that fetches and formats the latest
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changelog from the Nomad GitHub repository using a shell script. It showcases
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the use of templating with embedded environment variables and a multi-line script.
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```hcl
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action "fetch-latest-nomad-changelog" {
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command = "/bin/sh"
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args = ["-c",
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<<EOT
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curl -s https://raw.githubusercontent.com/hashicorp/nomad/main/CHANGELOG.md |
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awk 'BEGIN{
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# Setting record and field separators
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RS="## "; FS="\n";
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section=""; count=0
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}
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{
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# Processing only the first 3 sections after the header
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if (count < 3 && NR > 1){
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# Splitting the version line into components
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split($1, versionInfo, /[()]/);
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version=versionInfo[1];
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gsub(" ", "", version); # Removing spaces from version
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releaseDate=versionInfo[2];
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# Formatting URL components
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urlVersion=version; gsub("\\.", "", urlVersion); # Remove dots from version
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urlDate=releaseDate; gsub(" ", "-", urlDate); gsub(",", "", urlDate); # Replace spaces with hyphens and remove comma
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# Counting items under each section
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for(i=1; i<=NF; i++){
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if($i ~ /^[A-Z ]+:$/){
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gsub(":", "", $i);
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section=$i;
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itemCount[section]=0;
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}
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if(section && $i ~ /^\*/){
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itemCount[section]++;
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}
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}
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# Printing the extracted information
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printf "Version: %s\nRelease Date: %s\n", version, releaseDate;
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for (s in itemCount) {
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printf "%d %s, ", itemCount[s], s;
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}
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printf "\nLink: https://github.com/hashicorp/nomad/blob/main/CHANGELOG.md#%s-%s\n\n", urlVersion, tolower(urlDate);
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delete itemCount; # Clear the itemCount array for the next version
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count++;
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}
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}'
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EOT
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]
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}
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```
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