89 lines
3.6 KiB
Markdown
89 lines
3.6 KiB
Markdown
---
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description: |
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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 supports
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a fully machine-readable output setting, allowing you to use Packer in automated
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environments.
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layout: docs
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page_title: 'Machine-Readable Output - Command-Line'
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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 supports
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a fully machine-readable output setting, allowing you to use Packer in automated
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environments.
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The machine-readable output format is easy to use and read and was made with
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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 all
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output to become machine-readable on stdout. Logging, if enabled, continues to
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appear on stderr. An example of the output is shown 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, the output
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immediately becomes machine-friendly. Try some other commands with the
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`-machine-readable` flag to see!
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~> `-machine-readable` is designed for automated environments and is mutually-exclusive with the `-debug` flag, which is designed for interactive environments.
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## Format
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The machine readable format is a line-oriented, comma-delimited text format.
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This makes it extremely easy to parse using standard Unix tools such as awk or
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grep in addition to full programming languages like Ruby or 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 printed.
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- **target** is the target of the following output. This is empty if the
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message is related to Packer globally. Otherwise, this is generally a build
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name so you can relate output to a specific build while parallel builds
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are running.
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- **type** is the type of machine-readable message being outputted. There are
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a set of standard types which are covered later, but each component of
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Packer (builders, provisioners, etc.) may output their own custom types as
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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
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prior type. The exact amount and meaning of this data is type-dependent, so
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you must read the documentation associated with the type to
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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 escape
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sequence. Newlines become a literal `\n` within the output. Carriage returns
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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 [machine-readable
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format](/docs/machine-readable/index.html) complete documentation section. This
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section contains documentation on all the message types exposed by Packer core
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as well as all the components that ship with Packer by default.
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