89 lines
2.1 KiB
Markdown
89 lines
2.1 KiB
Markdown
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---
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layout: guides
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sidebar_current: isotime-template-function
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page_title: Using the isotime template function - Guides
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description: |-
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It can be a bit confusing to figure out how to format your isotime using the
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golang reference date string. Here is a small guide and some examples.
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---
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# Using the Isotime template function with a format string
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The way you format isotime in golang is a bit nontraditional compared to how
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you may be used to formatting datetime strings.
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Full docs and examples for the golang time formatting function can be found
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[here](https://golang.org/pkg/time/#example_Time_Format)
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However, the formatting basics are worth describing here. From the [golang docs](https://golang.org/pkg/time/#pkg-constants):
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>These are predefined layouts for use in Time.Format and time.Parse. The
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>reference time used in the layouts is the specific time:
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>
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>Mon Jan 2 15:04:05 MST 2006
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>
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>which is Unix time 1136239445. Since MST is GMT-0700, the reference time
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>can be thought of as
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>
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>01/02 03:04:05PM '06 -0700
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>
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> To define your own format, write down what the reference time would look like
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> formatted your way; see the values of constants like ANSIC, StampMicro or
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> Kitchen for examples. The model is to demonstrate what the reference time
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> looks like so that the Format and Parse methods can apply the same
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> transformation to a general time value.
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So what does that look like in a Packer template function?
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``` json
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{
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"variables":
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{
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"myvar": "packer-{{isotime \"2006-01-02 03:04:05\"}}"
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},
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"builders": [
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{
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"type": "null",
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"communicator": "none"
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}
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],
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"provisioners": [
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{
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"type": "shell-local",
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"inline": ["echo {{ user `myvar`}}"]
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}
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]
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}
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```
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You can switch out the variables section above with the following examples to
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get different timestamps:
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Date only, not time:
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```json
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"variables":
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{
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"myvar": "packer-{{isotime \"2006-01-02\"}}"
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},
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```
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A timestamp down to the millisecond:
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```json
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"variables":
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{
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"myvar": "packer-{{isotime \"Jan-_2-15:04:05.000\"}}"
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},
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```
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Or just the time as it would appear on a digital clock:
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```json
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"variables":
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{
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"myvar": "packer-{{isotime \"3:04PM\"}}"
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},
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```
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