86 lines
3.4 KiB
Markdown
86 lines
3.4 KiB
Markdown
---
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layout: "docs"
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page_title: "Machine-Readable Output - Command-Line"
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description: |-
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By default, the output of Packer is very human-readable. It uses nice formatting, spacing, and colors in order to make Packer a pleasure to use. However, Packer was built with automation in mind. To that end, Packer supports a fully machine-readable output setting, allowing you to use Packer in automated environments.
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---
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# Machine-Readable Output
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By default, the output of Packer is very human-readable. It uses nice
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formatting, spacing, and colors in order to make Packer a pleasure to use.
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However, Packer was built with automation in mind. To that end, Packer
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supports a fully machine-readable output setting, allowing you to use
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Packer in automated environments.
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The machine-readable output format is easy to use and read and was made
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with Unix tools in mind, so it is awk/sed/grep/etc. friendly.
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## Enabling
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The machine-readable output format can be enabled by passing the
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`-machine-readable` flag to any Packer command. This immediately enables
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all output to become machine-readable on stdout. Logging, if enabled,
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continues to appear on stderr. An example of the output is shown
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below:
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```text
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$ packer -machine-readable version
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1376289459,,version,0.2.4
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1376289459,,version-prerelease,
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1376289459,,version-commit,eed6ece
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1376289459,,ui,say,Packer v0.2.4.dev (eed6ece+CHANGES)
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```
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The format will be covered in more detail later. But as you can see,
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the output immediately becomes machine-friendly. Try some other commands
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with the `-machine-readable` flag to see!
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## Format
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The machine readable format is a line-oriented, comma-delimited text
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format. This makes it extremely easy to parse using standard Unix tools such
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as awk or grep in addition to full programming languages like Ruby or
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Python.
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The format is:
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```text
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timestamp,target,type,data...
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```
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Each component is explained below:
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* **timestamp** is a Unix timestamp in UTC of when the message was
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printed.
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* **target** is the target of the following output. This is empty if
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the message is related to Packer globally. Otherwise, this is generally
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a build name so you can relate output to a specific build while parallel
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builds are running.
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* **type** is the type of machine-readable message being outputted. There
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are a set of standard types which are covered later, but each component
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of Packer (builders, provisioners, etc.) may output their own custom types
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as well, allowing the machine-readable output to be infinitely flexible.
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* **data** is zero or more comma-seperated values associated with the prior
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type. The exact amount and meaning of this data is type-dependent, so you
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must read the documentation associated with the type to understand fully.
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Within the format, if data contains a comma, it is replaced with
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`%!(PACKER_COMMA)`. This was preferred over an escape character such as
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`\'` because it is more friendly to tools like awk.
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Newlines within the format are replaced with their respective standard
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escape sequence. Newlines become a literal `\n` within the output. Carriage
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returns become a literal `\r`.
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## Message Types
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The set of machine-readable message types can be found in the
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[machine-readable format](/docs/machine-readable/index.html)
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complete documentation section. This section contains documentation
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on all the message types exposed by Packer core as well as all the
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components that ship with Packer by default.
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