»The build block

The build block defines what builders are started, how to provision them and if necessary what to do with their artifacts using post-process.

To use builders in a build block you can either:

  • Set the sources array of string with references to pre-defined sources.

  • Define build-level source blocks or sources to use builders. This also allows you to set specific fields.

# build.pkr.hcl
build {
    # use the `name` field to name a build in the logs.
    # For example this present config will display 
    # "buildname.amazon-ebs.example-1" and "buildname.amazon-ebs.example-2"
    name = "buildname"

    sources = [
        # use the optional plural `sources` list to simply use a `source`
        # without changing any field.
        "source.amazon-ebs.example-1",
    ]

    source "source.amazon-ebs.example-2" {
        # Use the singular `source` block set specific fields.
        # Note that fields cannot be overwritten, in other words, you cannot 
        # set the 'output' field from the top-level source block and here.
        output = "different value"
        name = var.foo
    }

    provisioner "shell" {
        scripts = fileset(".", "scripts/{install,secure}.sh")
    }

    post-processor "shell-local" {
        inline = ["echo Hello World"]
    }
}

Define top-level source blocks to configure your builders. The list of available builders can be found in the builders section.

»Naming your builds

The optional name field of the build block can be used to set the name of a build. Named builds will prefix the log lines in a packer build with the name of the build block. For example:

source "null" "first-example" {
    communicator = "none"
}

source "null" "second-example" {
    communicator = "none"
}

build {
    name = "a"

    sources = [
        "sources.null.first-example",
        "sources.null.second-example",
    ]
}


build {
    sources = ["sources.null.second-example"]
}

Will output:

> packer build ./folder
Build 'a.null.first-example' finished.
Build 'a.null.second-example' finished.
Build 'null.second-example' finished.

==> Builds finished. The artifacts of successful builds are:
--> a.null.first-example: Did not export anything. This is the null builder
--> a.null.second-example: Did not export anything. This is the null builder
--> null.second-example: Did not export anything. This is the null builder

»Running only specific builds

The -only/-except flags will match a source's type.name and run 'only' matching builders (source) or all referenced builders 'except' the matching ones, for example with the same config file:

> packer build -only "*.second" ./folder
Build 'null.second-example' finished.
Build 'a.null.second-example' finished.

==> Builds finished. The artifacts of successful builds are:
--> a.null.second-example: Did not export anything. This is the null builder
--> null.second-example: Did not export anything. This is the null builder

Here 'a.null.first-example' was skipped.

»Related