/terraform-aws-gitlab-runner

Terraform module for AWS GitLab runners on ec2 (spot) instances

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Terraform module for GitLab auto scaling runners on AWS spot instances

The module

This Terraform modules creates a GitLab CI runner. A blog post describes the original version of the the runner. See the post at 040code. The original setup of the module is based on the blog post: Auto scale GitLab CI runners and save 90% on EC2 costs.

The runners created by the module use spot instances by default for running the builds using the docker+machine executor.

  • Shared cache in S3 with life cycle management to clear objects after x days.
  • Logs streamed to CloudWatch.
  • Runner agents registered automatically.

The name of the runner agent and runner is set with the overrides variable. Adding an agent runner name tag does not work.

...
overrides  = {
  name_sg                     = ""
  name_runner_agent_instance  = "Gitlab Runner Agent"
  name_docker_machine_runners = "Gitlab Runner Terraform"
}

//this doesn't work
agent_tags = merge(local.my_tags, map("Name", "Gitlab Runner Agent"))

The runner supports 3 main scenarios:

GitLab CI docker-machine runner - one runner agent

In this scenario the runner agent is running on a single EC2 node and runners are created by docker machine using spot instances. Runners will scale automatically based on the configuration. The module creates a S3 cache by default, which is shared across runners (spot instances).

runners-default

GitLab CI docker-machine runner - multiple runner agents

In this scenario the multiple runner agents can be created with different configuration by instantiating the module multiple times. Runners will scale automatically based on the configuration. The S3 cache can be shared across runners by managing the cache outside of the module.

runners-cache

GitLab Ci docker runner

In this scenario not docker machine is used but docker to schedule the builds. Builds will run on the same EC2 instance as the agent. No auto scaling is supported.

runners-docker

Prerequisites

Terraform

Ensure you have Terraform installed. The modules is based on Terraform 0.11, see .terraform-version for the used version. A handy tool to mange your Terraform version is tfenv.

On macOS it is simple to install tfenv using brew.

brew install tfenv

Next install a Terraform version.

tfenv install <version>

AWS

Ensure you have setup your AWS credentials. The module requires access to IAM, EC2, CloudWatch, S3 and SSM.

JQ & AWS CLI

In order to be able to destroy the module, you will need to run from a host with both jq and aws installed and accessible in the environment.

On macOS it is simple to install them using brew.

brew install jq awscli

Service linked roles

The GitLab runner EC2 instance requires the following service linked roles:

  • AWSServiceRoleForAutoScaling
  • AWSServiceRoleForEC2Spot

By default the EC2 instance is allowed to create the required roles, but this can be disabled by setting the option allow_iam_service_linked_role_creation to false. If disabled you must ensure the roles exist. You can create them manually or via Terraform.

resource "aws_iam_service_linked_role" "spot" {
  aws_service_name = "spot.amazonaws.com"
}

resource "aws_iam_service_linked_role" "autoscaling" {
  aws_service_name = "autoscaling.amazonaws.com"
}

GitLab runner token configuration

By default the runner is registered on initial deployment. In previous versions of this module this was a manual process. The manual process is still supported but will be removed in future releases. The runner token will be stored in the AWS SSM parameter store. See example for more details.

To register the runner automatically set the variable gitlab_runner_registration_config["registration_token"]. This token value can be found in your GitLab project, group, or global settings. For a generic runner you can find the token in the admin section. By default the runner will be locked to the target project, not run untagged. Below is an example of the configuration map.

gitlab_runner_registration_config = {
  registration_token = "<registration token>"
  tag_list           = "<your tags, comma separated>"
  description        = "<some description>"
  locked_to_project  = "true"
  run_untagged       = "false"
  maximum_timeout    = "3600"
  access_level       = "<not_protected OR ref_protected, ref_protected runner will only run on pipelines triggered on protected branches. Defaults to not_protected>"
}

For migration to the new setup simply add the runner token to the parameter store. Once the runner is started it will lookup the required values via the parameter store. If the value is null a new runner will be registered and a new token created/stored.

# set the following variables, look up the variables in your Terraform config.
# see your Terraform variables to fill in the vars below.
aws-region=<${var.aws_region}>
token=<runner-token-see-your-gitlab-runner>
parameter-name=<${var.environment}>-<${var.secure_parameter_store_runner_token_key}>

aws ssm put-parameter --overwrite --type SecureString  --name "${parameter-name}" --value ${token} --region "${aws-region}"

Once you have created the parameter, you must remove the variable runners_token from your config. The next time your GitLab runner instance is created it will look up the token from the SSM parameter store.

Finally, the runner still supports the manual runner creation. No changes are required. Please keep in mind that this setup will be removed in future releases.

Access runner instance

A few option are provided to access the runner instance:

  1. Provide a public ssh key to access the runner by setting ``.
  2. Provide a EC2 key pair to access the runner by setting ``.
  3. Access via the Session Manager (SSM) by setting enable_runner_ssm_access to true. The policy to allow access via SSM is not very restrictive.
  4. By setting none of the above, no keys or extra policies will be attached to the instance. You can still configure you own policies by attaching them to runner_agent_role_arn.

GitLab runner cache

By default the module creates a a cache for the runner in S3. Old objects are automatically removed via a configurable life cycle policy on the bucket.

Creation of the bucket can be disabled and managed outside this module. A good use case is for sharing the cache across multiple runners. For this purpose the cache is implemented as a sub module. For more details see the cache module. An example implementation of this use case can be found in the runner-public example.

Usage

Configuration

Update the variables in terraform.tfvars according to your needs and add the following variables. See the previous step for instructions on how to obtain the token.

runner_name  = "NAME_OF_YOUR_RUNNER"
gitlab_url   = "GITLAB_URL"
runner_token = "RUNNER_TOKEN"

The base image used to host the GitLab Runner agent is the latest available Amazon Linux 2 HVM EBS AMI. In previous versions of this module a hard coded list of AMIs per region was provided. This list has been replaced by a search filter to find the latest AMI. Setting the filter to amzn2-ami-hvm-2.0.20200207.1-x86_64-ebs will allow you to version lock the target AMI.

Usage module

Below is a basic examples of usages of the module. Regarding the dependencies such as a VPC and SSH keys, have a look at the default example.

module "runner" {
  # https://registry.terraform.io/modules/npalm/gitlab-runner/aws/
  source  = "npalm/gitlab-runner/aws"

  aws_region  = "eu-west-1"
  environment = "spot-runners"

  ssh_public_key = local_file.public_ssh_key.content

  vpc_id                   = module.vpc.vpc_id
  subnet_ids_gitlab_runner = module.vpc.private_subnets
  subnet_id_runners        = element(module.vpc.private_subnets, 0)

  runners_name       = "docker-default"
  runners_gitlab_url = "https://gitlab.com"

  gitlab_runner_registration_config = {
    registration_token = "my-token"
    tag_list           = "docker"
    description        = "runner default"
    locked_to_project  = "true"
    run_untagged       = "false"
    maximum_timeout    = "3600"
  }

}

Examples

A few examples are provided. Use the following steps to deploy. Ensure your AWS and Terraform environment is set up correctly. All commands below should be run from the terraform-aws-gitlab-runner/examples/<example-dir> directory.

SSH keys

SSH keys are generated by Terraform and stored in the generated directory of each example directory.

Versions

The version of Terraform is locked down via tfenv, see the .terraform-version file for the expected versions. Providers are locked down as well in the providers.tf file.

Configure

The examples are configured with defaults that should work in general. The examples are in general configured for the region Ireland eu-west-1. The only parameter that needs to be provided is the GitLab registration token. The token can be found in GitLab in the runner section (global, group or repo scope). Create a file terrafrom.tfvars and the registration token.

registration_token = "MY_TOKEN"

Run

Run terraform init to initialize Terraform. Next you can run terraform plan to inspect the resources that will be created.

To create the runner, run:

terraform apply

To destroy the runner, run:

terraform destroy

Requirements

Name Version
terraform >= 0.12
aws >= 3.35.0

Providers

Name Version
aws >= 3.35.0
null n/a

Modules

Name Source Version
cache ./modules/cache

Resources

Name
aws_ami
aws_autoscaling_group
aws_autoscaling_schedule
aws_availability_zone
aws_caller_identity
aws_cloudwatch_log_group
aws_eip
aws_iam_instance_profile
aws_iam_policy
aws_iam_role
aws_iam_role_policy
aws_iam_role_policy_attachment
aws_kms_alias
aws_kms_key
aws_launch_configuration
aws_security_group
aws_security_group_rule
aws_ssm_parameter
aws_subnet
null_data_source
null_resource

Inputs

Name Description Type Default Required
agent_tags Map of tags that will be added to agent EC2 instances. map(string) {} no
allow_iam_service_linked_role_creation Boolean used to control attaching the policy to a runner instance to create service linked roles. bool true no
ami_filter List of maps used to create the AMI filter for the Gitlab runner agent AMI. Must resolve to an Amazon Linux 1 or 2 image. map(list(string)) 
{
  "name": [
    "amzn2-ami-hvm-2.*-x86_64-ebs"
  ]
}
 no
ami_owners The list of owners used to select the AMI of Gitlab runner agent instances. list(string) 
[
  "amazon"
]
 no
arn_format ARN format to be used. May be changed to support deployment in GovCloud/China regions. string "arn:aws" no
asg_delete_timeout Timeout when trying to delete the Runner ASG. string "10m" no
aws_region AWS region. string n/a yes
aws_zone Deprecated. Will be removed in the next major release. string "a" no
cache_bucket Configuration to control the creation of the cache bucket. By default the bucket will be created and used as shared cache. To use the same cache across multiple runners disable the creation of the cache and provide a policy and bucket name. See the public runner example for more details. map(any) 
{
  "bucket": "",
  "create": true,
  "policy": ""
}
 no
cache_bucket_name_include_account_id Boolean to add current account ID to cache bucket name. bool true no
cache_bucket_prefix Prefix for s3 cache bucket name. string "" no
cache_bucket_set_random_suffix Append the cache bucket name with a random string suffix bool false no
cache_bucket_versioning Boolean used to enable versioning on the cache bucket, false by default. bool false no
cache_expiration_days Number of days before cache objects expires. number 1 no
cache_shared Enables cache sharing between runners, false by default. bool false no
cloudwatch_logging_retention_in_days Retention for cloudwatch logs. Defaults to unlimited number 0 no
docker_machine_download_url Full url pointing to a linux x64 distribution of docker machine. Once set docker_machine_version will be ingored. For example the GitLab version, https://gitlab-docker-machine-downloads.s3.amazonaws.com/v0.16.2-gitlab.2/docker-machine. string "https://gitlab-docker-machine-downloads.s3.amazonaws.com/v0.16.2-gitlab.2/docker-machine" no
docker_machine_iam_policy_arns List of policy ARNs to be added to the instance profile of the docker machine runners. list(string) [] no
docker_machine_instance_type Instance type used for the instances hosting docker-machine. string "m5.large" no
docker_machine_options List of additional options for the docker machine config. Each element of this list must be a key=value pair. E.g. '["amazonec2-zone=a"]' list(string) [] no
docker_machine_role_json Docker machine runner instance override policy, expected to be in JSON format. string "" no
docker_machine_security_group_description A description for the docker-machine security group string "A security group containing docker-machine instances" no
docker_machine_spot_price_bid Spot price bid. string "0.06" no
docker_machine_version By default docker_machine_download_url is used to set the docker machine version. Version of docker-machine. The version will be ingored once docker_machine_download_url is set. string "" no
enable_asg_recreation Enable automatic redeployment of the Runner ASG when the Launch Configs change. bool true no
enable_cloudwatch_logging Boolean used to enable or disable the CloudWatch logging. bool true no
enable_docker_machine_ssm_access Add IAM policies to the docker-machine instances to connect via the Session Manager. bool false no
enable_eip Enable the assignment of an EIP to the gitlab runner instance bool false no
enable_forced_updates DEPRECATED! and is replaced by enable_asg_recreation. Setting this variable to true will do the oposite as expected. For backward compatibility the variable will remain some releases. Old desription: Enable automatic redeployment of the Runner ASG when the Launch Configs change. string null no
enable_gitlab_runner_ssh_access Enables SSH Access to the gitlab runner instance. bool false no
enable_kms Let the module manage a KMS key, logs will be encrypted via KMS. Be-aware of the costs of an custom key. bool false no
enable_manage_gitlab_token Boolean to enable the management of the GitLab token in SSM. If true the token will be stored in SSM, which means the SSM property is a terraform managed resource. If false the Gitlab token will be stored in the SSM by the user-data script during creation of the the instance. However the SSM parameter is not managed by terraform and will remain in SSM after a terraform destroy. bool true no
enable_ping Allow ICMP Ping to the ec2 instances. bool false no
enable_runner_ssm_access Add IAM policies to the runner agent instance to connect via the Session Manager. bool false no
enable_runner_user_data_trace_log Enable bash xtrace for the user data script that creates the EC2 instance for the runner agent. Be aware this could log sensitive data such as you GitLab runner token. bool false no
enable_schedule Flag used to enable/disable auto scaling group schedule for the runner instance. bool false no
environment A name that identifies the environment, used as prefix and for tagging. string n/a yes
gitlab_runner_egress_rules List of egress rules for the gitlab runner instance. 
list(object({
    cidr_blocks      = list(string)
    ipv6_cidr_blocks = list(string)
    prefix_list_ids  = list(string)
    from_port        = number
    protocol         = string
    security_groups  = list(string)
    self             = bool
    to_port          = number
    description      = string
  }))
 
[
  {
    "cidr_blocks": [
      "0.0.0.0/0"
    ],
    "description": null,
    "from_port": 0,
    "ipv6_cidr_blocks": [
      "::/0"
    ],
    "prefix_list_ids": null,
    "protocol": "-1",
    "security_groups": null,
    "self": null,
    "to_port": 0
  }
]
 no
gitlab_runner_registration_config Configuration used to register the runner. See the README for an example, or reference the examples in the examples directory of this repo. map(string) 
{
  "access_level": "",
  "description": "",
  "locked_to_project": "",
  "maximum_timeout": "",
  "registration_token": "",
  "run_untagged": "",
  "tag_list": ""
}
 no
gitlab_runner_security_group_description A description for the gitlab-runner security group string "A security group containing gitlab-runner agent instances" no
gitlab_runner_security_group_ids A list of security group ids that are allowed to access the gitlab runner agent list(string) [] no
gitlab_runner_ssh_cidr_blocks List of CIDR blocks to allow SSH Access to the gitlab runner instance. list(string) [] no
gitlab_runner_version Version of the GitLab runner. string "13.8.0" no
instance_role_json Default runner instance override policy, expected to be in JSON format. string "" no
instance_type Instance type used for the GitLab runner. string "t3.micro" no
kms_alias_name Alias added to the kms_key (if created and not provided by kms_key_id) string "" no
kms_deletion_window_in_days Key rotation window, set to 0 for no rotation. Only used when enable_kms is set to true. number 7 no
kms_key_id KMS key id to encrypted the CloudWatch logs. Ensure CloudWatch has access to the provided KMS key. string "" no
log_group_name Option to override the default name (environment) of the log group, requires enable_cloudwatch_logging = true. string null no
metrics_autoscaling A list of metrics to collect. The allowed values are GroupDesiredCapacity, GroupInServiceCapacity, GroupPendingCapacity, GroupMinSize, GroupMaxSize, GroupInServiceInstances, GroupPendingInstances, GroupStandbyInstances, GroupStandbyCapacity, GroupTerminatingCapacity, GroupTerminatingInstances, GroupTotalCapacity, GroupTotalInstances. list(string) null no
overrides This maps provides the possibility to override some defaults. The following attributes are supported: name_sg overwrite the Name tag for all security groups created by this module. name_runner_agent_instance override the Name tag for the ec2 instance defined in the auto launch configuration. name_docker_machine_runners ovverrid the Name tag spot instances created by the runner agent. map(string) 
{
  "name_docker_machine_runners": "",
  "name_runner_agent_instance": "",
  "name_sg": ""
}
 no
permissions_boundary Name of permissions boundary policy to attach to AWS IAM roles string "" no
runner_ami_filter List of maps used to create the AMI filter for the Gitlab runner docker-machine AMI. map(list(string)) 
{
  "name": [
    "ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"
  ]
}
 no
runner_ami_owners The list of owners used to select the AMI of Gitlab runner docker-machine instances. list(string) 
[
  "099720109477"
]
 no
runner_iam_policy_arns List of policy ARNs to be added to the instance profile of the gitlab runner agent ec2 instance. list(string) [] no
runner_instance_ebs_optimized Enable the GitLab runner instance to be EBS-optimized. bool true no
runner_instance_enable_monitoring Enable the GitLab runner instance to have detailed monitoring. bool true no
runner_instance_spot_price By setting a spot price bid price the runner agent will be created via a spot request. Be aware that spot instances can be stopped by AWS. string null no
runner_root_block_device The EC2 instance root block device configuration. Takes the following keys: delete_on_termination, volume_type, volume_size, encrypted, iops map(string) {} no
runner_tags Map of tags that will be added to runner EC2 instances. map(string) {} no
runners_additional_volumes Additional volumes that will be used in the runner config.toml, e.g Docker socket list(any) [] no
runners_concurrent Concurrent value for the runners, will be used in the runner config.toml. number 10 no
runners_docker_runtime docker runtime for runners, will be used in the runner config.toml string "" no
runners_ebs_optimized Enable runners to be EBS-optimized. bool true no
runners_environment_vars Environment variables during build execution, e.g. KEY=Value, see runner-public example. Will be used in the runner config.toml list(string) [] no
runners_executor The executor to use. Currently supports docker+machine or docker. string "docker+machine" no
runners_gitlab_url URL of the GitLab instance to connect to. string n/a yes
runners_helper_image Overrides the default helper image used to clone repos and upload artifacts, will be used in the runner config.toml string "" no
runners_iam_instance_profile_name IAM instance profile name of the runners, will be used in the runner config.toml string "" no
runners_idle_count Idle count of the runners, will be used in the runner config.toml. number 0 no
runners_idle_time Idle time of the runners, will be used in the runner config.toml. number 600 no
runners_image Image to run builds, will be used in the runner config.toml string "docker:18.03.1-ce" no
runners_install_amazon_ecr_credential_helper Install amazon-ecr-credential-helper inside userdata_pre_install script bool false no
runners_limit Limit for the runners, will be used in the runner config.toml. number 0 no
runners_machine_autoscaling Set autoscaling parameters based on periods, see https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runnersmachine-section 
list(object({
    periods    = list(string)
    idle_count = number
    idle_time  = number
    timezone   = string
  }))
 [] no
runners_max_builds Max builds for each runner after which it will be removed, will be used in the runner config.toml. By default set to 0, no maxBuilds will be set in the configuration. number 0 no
runners_monitoring Enable detailed cloudwatch monitoring for spot instances. bool false no
runners_name Name of the runner, will be used in the runner config.toml. string n/a yes
runners_off_peak_idle_count Deprecated, please use runners_machine_autoscaling. Off peak idle count of the runners, will be used in the runner config.toml. number -1 no
runners_off_peak_idle_time Deprecated, please use runners_machine_autoscaling. Off peak idle time of the runners, will be used in the runner config.toml. number -1 no
runners_off_peak_periods Deprecated, please use runners_machine_autoscaling. Off peak periods of the runners, will be used in the runner config.toml. string null no
runners_off_peak_timezone Deprecated, please use runners_machine_autoscaling. Off peak idle time zone of the runners, will be used in the runner config.toml. string null no
runners_output_limit Sets the maximum build log size in kilobytes, by default set to 4096 (4MB) number 4096 no
runners_post_build_script Commands to be executed on the Runner just after executing the build, but before executing after_script. string "\"\"" no
runners_pre_build_script Script to execute in the pipeline just before the build, will be used in the runner config.toml string "\"\"" no
runners_pre_clone_script Commands to be executed on the Runner before cloning the Git repository. this can be used to adjust the Git client configuration first, for example. string "\"\"" no
runners_privileged Runners will run in privileged mode, will be used in the runner config.toml bool true no
runners_disable_cache Runners will not use local cache, will be used in the runner config.toml bool false no
runners_pull_policy pull_policy for the runners, will be used in the runner config.toml string "always" no
runners_request_concurrency Limit number of concurrent requests for new jobs from GitLab (default 1) number 1 no
runners_request_spot_instance Whether or not to request spot instances via docker-machine bool true no
runners_root_size Runner instance root size in GB. number 16 no
runners_services_volumes_tmpfs n/a 
list(object({
    volume  = string
    options = string
  }))
 [] no
runners_shm_size shm_size for the runners, will be used in the runner config.toml number 0 no
runners_token Token for the runner, will be used in the runner config.toml. string "__REPLACED_BY_USER_DATA__" no
runners_use_private_address Restrict runners to the use of a private IP address bool true no
runners_volumes_tmpfs n/a 
list(object({
    volume  = string
    options = string
  }))
 [] no
schedule_config Map containing the configuration of the ASG scale-in and scale-up for the runner instance. Will only be used if enable_schedule is set to true. map(any) 
{
  "scale_in_count": 0,
  "scale_in_recurrence": "0 18 * * 1-5",
  "scale_out_count": 1,
  "scale_out_recurrence": "0 8 * * 1-5"
}
 no
secure_parameter_store_runner_token_key The key name used store the Gitlab runner token in Secure Parameter Store string "runner-token" no
ssh_key_pair Set this to use existing AWS key pair string null no
subnet_id_runners List of subnets used for hosting the gitlab-runners. string n/a yes
subnet_ids_gitlab_runner Subnet used for hosting the GitLab runner. list(string) n/a yes
tags Map of tags that will be added to created resources. By default resources will be tagged with name and environment. map(string) {} no
userdata_post_install User-data script snippet to insert after GitLab runner install string "" no
userdata_pre_install User-data script snippet to insert before GitLab runner install string "" no
vpc_id The target VPC for the docker-machine and runner instances. string n/a yes

Outputs

Name Description
runner_agent_role_arn ARN of the role used for the ec2 instance for the GitLab runner agent.
runner_agent_role_name Name of the role used for the ec2 instance for the GitLab runner agent.
runner_agent_sg_id ID of the security group attached to the GitLab runner agent.
runner_as_group_name Name of the autoscaling group for the gitlab-runner instance
runner_cache_bucket_arn ARN of the S3 for the build cache.
runner_cache_bucket_name Name of the S3 for the build cache.
runner_eip EIP of the Gitlab Runner
runner_role_arn ARN of the role used for the docker machine runners.
runner_role_name Name of the role used for the docker machine runners.
runner_sg_id ID of the security group attached to the docker machine runners.

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