--- layout: docs page_title: Format CLI output with templates description: |- Customize the output of Nomad CLI commands with Go template syntax. Practice interacting with unfamiliar template contexts. --- # Format CLI output with templates When using Nomad at an intermediate to advanced level, you'll need to interface with other systems or customize output generated by Nomad. The `-t` flag is a powerful way to pass a template in Go's text/template format to several of the Nomad commands that generate output based on the API. This allows you to filter and customize the output to meet your specific needs. The commands that allow for the -t flag are: - `nomad acl policy list` - `nomad acl token list` - `nomad alloc status` - `nomad deployment list` - `nomad deployment status` - `nomad eval status` - `nomad job deployments` - `nomad job history` - `nomad job inspect` - `nomad namespace list` - `nomad node status` - `nomad plugin status` - `nomad quota list` - `nomad volume status` This guide will teach you how to explore the objects that are returned to the template engine and how to use template syntax to format the output into a custom form. ## Prerequisites This guide assumes the following: - Familiarity with Go's text/template syntax. You can learn more about it in the [Go template syntax][go-template-syntax] reference. - That you are running these commands against a Nomad cluster with an active workload. You can create a minimal environment using a dev agent, started with `sudo nomad agent -dev`, then running at least one Nomad job. You can use `nomad init -short` to create a sample Docker job or provide your own Nomad job. ## Note the shell-specific syntax When using the -t flag, you need to correctly handle string literals based on your shell environment. In a POSIX shell, you can run the following with a single quote: ```shell-session $ nomad node status -t '{{printf "%#+v" .}}' ``` In a Windows shell (for example, PowerShell), use single quotes but escape the double quotes inside the parameter as follows: ```powershell PS> nomad node status -t '{{printf \"%#+v\" .}}' ``` In this guide, you can select examples with the proper escaping using the tabs above the snippets. ## Start discovering objects The `printf` function and the `"%#+v"` format string are critical tools for you in exploring an unfamiliar template context. Run the following command to output the context being passed to the template in Go object format. ```shell-session $ nomad node status -t '{{printf "%#+v" .}}' ``` ```powershell PS> nomad node status -t '{{printf \"%#+v\" .}}' ``` ```plaintext []*api.NodeListStub{(*api.NodeListStub)(0xc0003fa160), (*api.NodeListStub)(0xc0003fa0b0), (*api.NodeListStub)(0xc0003fa000)} ``` The output indicates that the context consists of a list (`[]`) of pointers (`*`) to `api.NodeListStub` objects. The list will also show one NodeListStub object per client node in your cluster's server state. You can explore these api.NodeListStub object by using the `range` control over the list. ```shell-session $ nomad node status -t '{{range .}}{{printf "%#+v" .}}{{end}}' ``` ```powershell PS> nomad node status -t '{{range .}}{{printf \"%#+v\" .}}{{end}}' ``` ```plaintext &api.NodeListStub{Address:"10.0.2.52", ID:"4f60bc83-71a2-7790-b120-4e55d0e6ed34", Datacenter:"dc1", Name:"nomad-client-2.node.consul", NodeClass:"", Version:"0.12.0", Drain:false, SchedulingEligibility:"eligible", Status:"ready", ... ``` If you have a lot of client nodes in your cluster state, this output will be unwieldy. In that case, you can use `with` and the index function to get the first list item. ```shell-session $ nomad node status -t '{{with index . 0}}{{printf "%#+v" .}}{{end}}' ``` ```powershell PS> nomad node status -t '{{with index . 0}}{{printf \"%#+v\" .}}{{end}}' &api.NodeListStub{Address:"10.0.2.52", ID:"4f60bc83-71a2-7790-b120-4e55d0e6ed34", Datacenter:"dc1", Name:"nomad-client-2.node.consul", NodeClass:"", Version:"0.12.0", Drain:false, SchedulingEligibility:"eligible", Status:"ready", ... ``` ```plaintext &api.NodeListStub{Address:"10.0.2.52", ID:"4f60bc83-71a2-7790-b120-4e55d0e6ed34", Datacenter:"dc1", Name:"nomad-client-2.node.consul", NodeClass:"", Version:"0.12.0", Drain:false, SchedulingEligibility:"eligible", Status:"ready", ... ``` Finally, output `Name` and `Version` for each client in the cluster. ```shell-session $ nomad node status -t '{{range .}}{{printf "%s: %s\n" .Name .Version}}{{end}}' ``` ```powershell PS> nomad node status -t '{{range .}}{{printf \"%s: %s\n\" .Name .Version}}{{end}}' ``` ```plaintext nomad-client-2.node.consul: 0.12.0 nomad-client-3.node.consul: 0.12.0 nomad-client-1.node.consul: 0.12.0 ``` ## Make quiet output Suppose you want to create a reduced version of the `nomad job status` output to show just the running job IDs in your cluster and nothing else. ```shell-session $ nomad job inspect -t '{{range .}}{{if eq .Status "running"}}{{ println .Name}}{{end}}{{end}}' ``` ```powershell PS> nomad job inspect -t '{{range .}}{{if eq .Status \"running\"}}{{ println .Name}}{{end}}{{end}}' ``` Nomad will output the job IDs for every running job in your cluster. For example: ```plaintext fabio sockshop-carts sockshop-catalogue sockshop-frontend sockshop-infra sockshop-orders sockshop-payment sockshop-shipping sockshop-user ``` ### Challenge yourself Allocations have a slightly different shape. How might you create similar output from the `nomad alloc status` command? Make sure that your Nomad cluster has at least one allocation running and then use the printf technique from earlier to explore the values sent into the template. Print the context that you are passed from the command using the printf command. ```shell-session $ nomad alloc status -t '{{printf "%#+v" . }}' ``` ```powershell PS> nomad alloc status -t '{{printf \"%#+v\" . }}' ``` ```plaintext []*api.AllocationListStub ... ``` Note that the first thing that you receive is a list (`[]`) of pointers (`*`) to `AllocationListStub` objects. Use `range` to traverse each item in the list. ```shell-session $ nomad alloc status -t '{{range .}}{{printf "%#+v" . }}{{end}}' ``` ```powershell PS> nomad alloc status -t '{{range .}}{{printf \"%#+v\" . }}{{end}}' ``` ```plaintext &api.AllocationListStub{ID:"30663b68-4d8a-aada-4ad2-011b1acae3a1", EvalID:"c5eda90b-f675-048e-b2f7-9ced30e4916b", Name:"sockshop-user.userdb[0]", Namespace:"default", NodeID:"3be35c12-70aa-8816-195e-a4630a457727", NodeName:"nomad-client-3.node.consul", JobID:"sockshop-user", JobType:"service", JobVersion:0x0, ... ``` If you have a lot of allocations running, this could get unwieldy. In that case, you can use `with` and the index function to get the first list item. ```shell-session $ nomad alloc status -t '{{with index . 0}}{{printf "%#+v" . }}{{end}}' ``` ```powershell PS> nomad alloc status -t '{{with index . 0}}{{printf \"%#+v\" . }}{{end}}' ``` ```plaintext &api.AllocationListStub{ID:"30663b68-4d8a-aada-4ad2-011b1acae3a1", EvalID:"c5eda90b-f675-048e-b2f7-9ced30e4916b", Name:"sockshop-user.userdb[0]", Namespace:"default", NodeID:"3be35c12-70aa-8816-195e-a4630a457727", NodeName:"nomad-client-3.node.consul", JobID:"sockshop-user", JobType:"service", JobVersion:0x0, ... ``` The fields on the AllocationListStub object that give insight into the running state of an allocation are `DesiredStatus` and `ClientStatus`. -> **Did you know?** The definition of an [AllocationListStub][] object and valid values for the DesiredStatus and ClientStatus are located in Nomad's [api package][]. Take a moment to look at it and see what other information you might be interested in displaying with templates. Update your template to show items with a DesiredStatus of "run" and a client status of "running" or "pending." ```shell-session $ nomad alloc status -t '{{range .}}{{if and (eq .DesiredStatus "run") (or (eq .ClientStatus "running") (eq .ClientStatus "pending"))}}{{println .ID}}{{end}}{{end}}' ``` ```powershell PS> nomad alloc status -t '{{range .}}{{if and (eq .DesiredStatus \"run\") (or (eq .ClientStatus \"running\") (eq .ClientStatus \"pending\"))}}{{println .ID}}{{end}}{{end}}' ``` ```plaintext 30663b68-4d8a-aada-4ad2-011b1acae3a1 11b916da-d679-1718-26f3-f6cd499bfdb8 68bcb157-359f-9293-d091-5a8ef71475ad ... ``` You now have a list of the IDs for all of the allocations running in your Nomad cluster. ## Retrieve a template from file Using the command line to write templates becomes challenging as the template becomes more complex. By writing a template in its own file, you can use comments, span multiple lines, and indent conditionals in order to make them more readable to you and to other operators. Consider using some of these techniques to include the template data into the command. Create a file named running_jobs.tmpl with the following content. ```plaintext {{- /* Get Running Jobs Run with `nomad job inspect -t "$(cat running_jobs.tmpl)"` */ -}} {{- range . -}} {{- if eq .Status "running" -}} {{- println .Name -}} {{- end -}} {{- end -}} ``` Now, use a subshell to read the file into a variable ```shell-session $ nomad job inspect -t "$(cat running_jobs.tmpl)" ``` Create a file named running_jobs.tmpl with the following content. ```plaintext {{- /* Get Running Jobs Run with: $content=Get-Content running_jobs.tmpl -Raw; nomad job inspect -t $content */ -}} {{- range . -}} {{- if eq .Status \"running\" -}} {{- println .Name -}} {{- end -}} {{- end -}} ``` Now, use a subshell to read the file into a variable ```powershell PS> $content=Get-Content running_jobs.tmpl -Raw; nomad job inspect -t $content ``` ## Learn more In this guide, you learned how to: - Customize the output of several Nomad commands using Go's text/template syntax. - Use the `printf` function to discover what is available in the template's context. - Use a template definition contained in a file as part of the command. [go-template-syntax]: /nomad/docs/reference/go-template-syntax [allocationliststub]: https://godoc.org/github.com/hashicorp/nomad/api#AllocationListStub [api package]: https://godoc.org/github.com/hashicorp/nomad/api