Runtime configuration

Search…
The runtime configuration is an optional setup applied to individual runs instead of being global to the stack. It's defined in .spacelift/config.yml YAML file at the root of your repository. A single file is used to define settings for all stacks associated with its host Git repository, so the file structure looks like this:
.spacelift/config.yml
1
version: "1"
2
​
3
stack_defaults:
4
    runner_image: your/first:runner
5
    # Note that tflint is not installed by
6
    # default - this example assumes that your
7
    # runner image has this available.
8
    before_init:
9
        - terraform fmt -check
10
        - tflint
11
​
12
# Note that every field in the configuration is
13
# optional, and has a reasonable default. This file
14
# allows you to override those defaults, and you can
15
# merely override individual fields.
16
stacks:
17
    # The key of is the immutable slug of your stack
18
    # which you will find in the URL.
19
    babys-first-stack: &shared
20
        before_apply:
21
            - hostname
22
        project_root: infra
23
        terraform_version: 0.12.4
24
    babys-second-stack:
25
        <<: *shared
26
        terraform_version: 0.13.0
27
        environment:
28
            AWS_REGION: eu-west-1
29
        
Copied!
The top level of the file contains three keys - version which in practice is currently ignored but may be useful in the future, stacks containing a mapping of immutable stack id to the stack configuration block and stack_defaults, containing the defaults common to all stacks using this source code repository. Note that corresponding stack-specific settings will override any stack defaults.
.
Since we adopted everyone's favorite data serialization format, you can use all the YAML shenanigans you can think of - things like anchors and inline JSON can keep your config DRY and neat.
Purpose of runtime configuration
The whole concept of runtime configuration may initially sound unnecessary, but it ultimately allows flexibility that would otherwise be hard to achieve. In general, its purpose is to preview effects of changes not related to the source code (eg. Terraform or Pulumi version upgrades, variable changes etc.), before they become an established part of your infra.
While stack environment applies both to tracked and non-tracked branches, a runtime configuration change can be pushed to a feature branch, which triggers proposed runs allowing you to preview the changes before they have a chance to affect your state.
If the runtime configuration file is not present or does not contain your stack, default values are used - refer to each setting for its respective default.
Stacks configuration block
before_ and after_ hooks
Each collection defaults to an empty array.
These scripts allow customizing the Spacelift workflow - see the relevant documentation here. The following are available:
before_init
after_init
before_plan
after_plan
before_apply
after_apply
before_perform
after_perform
before_destroy
after_destroy
environment map
Defaults to an empty map.
The environment allows you to declaratively pass some environment variables to the runtime configuration of the Stack. In case of a conflict, these variables will override both the ones passed via attached Contexts and those directly set in Stack's environment.
project_root setting
Defaults to an empty string, pointing to the working directory for the run.
Project root is the path of your project directory inside the Hub repository. You can use this setting to point Spacelift to the right place if the repo contains source code for multiple stacks in various folders or serves multiple purposes like those increasingly popular monorepos combining infrastructure definitions with source code, potentially even for multiple applications.
runner_image setting
Defaults to public.ecr.aws/spacelift/runner-terraform:latest​
The runner image is the Docker image used to run your workloads. By making it a runtime setting, Spacelift allows testing the image before it modifies your infrastructure.
terraform_version setting
Defaults to the latest known supported Terraform version.
This setting is only valid on Terraform stacks and specifies the Terraform version that the run will use. The main use case is testing a newer version of Terraform before you use it to change the state since the way back is very hard. This version can only be equal to or higher than the one already used to apply state changes. For more details on Terraform version management, please refer to its dedicated help section.
Pulumi version management is based on Docker images.
Context
YAML reference
Last modified 2mo ago
Copy link
Contents
Purpose of runtime configuration
Stacks configuration block
before_ and after_ hooks
environment map
project_root setting
runner_image setting
terraform_version setting
Purpose of runtime configuration

`Stacks` configuration block

`before_` and `after_` hooks

`environment` map

`project_root` setting

`runner_image` setting

`terraform_version` setting
