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author | Marcia Ramos <virtua.creative@gmail.com> | 2017-11-24 20:02:01 +0000 |
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committer | Marcia Ramos <virtua.creative@gmail.com> | 2017-11-24 20:02:01 +0000 |
commit | 25b35630a7471e8308dc052802a22c90f1e2e03a (patch) | |
tree | 0e602fe5605bd0faa1dec70e8d47a9578c8a9ecc | |
parent | 3c71af9fdf0858470f6430db95ab4c2c5625791b (diff) | |
parent | bca153e538f8007d1dc8e906cdf85e4a92829b3b (diff) | |
download | gitlab-ce-25b35630a7471e8308dc052802a22c90f1e2e03a.tar.gz |
Merge branch 'docs/runner-aws-spot-instances' into 'master'
Add article on autoscaling GitLab Runner on AWS
Closes #39650
See merge request gitlab-org/gitlab-ce!15313
-rw-r--r-- | doc/articles/index.md | 1 | ||||
-rw-r--r-- | doc/articles/runner_autoscale_aws/index.md | 410 |
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diff --git a/doc/articles/index.md b/doc/articles/index.md index 798d4cbf4ff..862fe0868a6 100644 --- a/doc/articles/index.md +++ b/doc/articles/index.md @@ -26,6 +26,7 @@ Build, test, and deploy the software you develop with [GitLab CI/CD](../ci/READM | Article title | Category | Publishing date | | :------------ | :------: | --------------: | +| [Autoscaling GitLab Runners on AWS](runner_autoscale_aws/index.md) | Admin guide | 2017-11-24 | | [How to test and deploy Laravel/PHP applications with GitLab CI/CD and Envoy](laravel_with_gitlab_and_envoy/index.md) | Tutorial | 2017-08-31 | | [How to deploy Maven projects to Artifactory with GitLab CI/CD](artifactory_and_gitlab/index.md) | Tutorial | 2017-08-15 | | [Making CI Easier with GitLab](https://about.gitlab.com/2017/07/13/making-ci-easier-with-gitlab/) | Concepts | 2017-07-13 | diff --git a/doc/articles/runner_autoscale_aws/index.md b/doc/articles/runner_autoscale_aws/index.md new file mode 100644 index 00000000000..9d4c4a57ce5 --- /dev/null +++ b/doc/articles/runner_autoscale_aws/index.md @@ -0,0 +1,410 @@ +--- +last_updated: 2017-11-24 +--- + +> **[Article Type](../../development/writing_documentation.html#types-of-technical-articles):** Admin guide || +> **Level:** intermediary || +> **Author:** [Achilleas Pipinellis](https://gitlab.com/axil) || +> **Publication date:** 2017/11/24 + +# Autoscaling GitLab Runner on AWS + +One of the biggest advantages of GitLab Runner is its ability to automatically +spin up and down VMs to make sure your builds get processed immediately. It's a +great feature, and if used correctly, it can be extremely useful in situations +where you don't use your Runners 24/7 and want to have a cost-effective and +scalable solution. + +## Introduction + +In this tutorial, we'll explore how to properly configure a GitLab Runner in +AWS that will serve as the bastion where it will spawn new Docker machines on +demand. + +In addition, we'll make use of [Amazon's EC2 Spot instances][spot] which will +greatly reduce the costs of the Runner instances while still using quite +powerful autoscaling machines. + +## Prerequisites + +NOTE: **Note:** +A familiarity with Amazon Web Services (AWS) is required as this is where most +of the configuration will take place. + +Your GitLab instance is going to need to talk to the Runners over the network, +and that is something you need think about when configuring any AWS security +groups or when setting up your DNS configuration. + +For example, you can keep the EC2 resources segmented away from public traffic +in a different VPC to better strengthen your network security. Your environment +is likely different, so consider what works best for your situation. + +### AWS security groups + +Docker Machine will attempt to use a +[default security group](https://docs.docker.com/machine/drivers/aws/#security-group) +with rules for port `2376`, which is required for communication with the Docker +daemon. Instead of relying on Docker, you can create a security group with the +rules you need and provide that in the Runner options as we will +[see below](#the-runners-machine-section). This way, you can customize it to your +liking ahead of time based on your networking environment. + +### AWS credentials + +You'll need an [AWS Access Key](https://docs.aws.amazon.com/general/latest/gr/managing-aws-access-keys.html) +tied to a user with permission to scale (EC2) and update the cache (via S3). +Create a new user with [policies](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-policies-for-amazon-ec2.html) +for EC2 (AmazonEC2FullAccess) and S3 (AmazonS3FullAccess). To be more secure, +you can disable console login for that user. Keep the tab open or copy paste the +security credentials in an editor as we'll use them later during the +[Runner configuration](#the-runners-machine-section). + +## Prepare the bastion instance + +The first step is to install GitLab Runner in an EC2 instance that will serve +as the bastion that spawns new machines. This doesn't have to be a powerful +machine since it will not run any jobs itself, a `t2.micro` instance will do. +This machine will be a dedicated host since we need it always up and running, +thus it will be the only standard cost. + +NOTE: **Note:** +For the bastion instance, choose a distribution that both Docker and GitLab +Runner support, for example either Ubuntu, Debian, CentOS or RHEL will work fine. + +Install the prerequisites: + +1. Log in to your server +1. [Install GitLab Runner from the official GitLab repository](https://docs.gitlab.com/runner/install/linux-repository.html) +1. [Install Docker](https://docs.docker.com/engine/installation/#server) +1. [Install Docker Machine](https://docs.docker.com/machine/install-machine/) + +Now that the Runner is installed, it's time to register it. + +## Registering the GitLab Runner + +Before configuring the GitLab Runner, you need to first register it, so that +it connects with your GitLab instance: + +1. [Obtain a Runner token](../../ci/runners/README.md) +1. [Register the Runner](https://docs.gitlab.com/runner/register/index.html#gnu-linux) +1. When asked the executor type, enter `docker+machine` + +You can now move on to the most important part, configuring the GitLab Runner. + +TIP: **Tip:** +If you want every user in your instance to be able to use the autoscaled Runners, +register the Runner as a shared one. + +## Configuring the GitLab Runner + +Now that the Runner is registered, you need to edit its configuration file and +add the required options for the AWS machine driver. + +Let's first break it down to pieces. + +### The global section + +In the global section, you can define the limit of the jobs that can be run +concurrently across all Runners (`concurrent`). This heavily depends on your +needs, like how many users your Runners will accommodate, how much time your +builds take, etc. You can start with something low like `10`, and increase or +decrease its value going forward. + +The `check_interval` option defines how often the Runner should check GitLab +for new jobs, in seconds. + +Example: + +```toml +concurrent = 10 +check_interval = 0 +``` + +[Read more](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-global-section) +about all the options you can use. + +### The `runners` section + +From the `[[runners]]` section, the most important part is the `executor` which +must be set to `docker+machine`. Most of those settings are taken care of when +you register the Runner for the first time. + +`limit` sets the maximum number of machines (running and idle) that this Runner +will spawn. For more info check the [relationship between `limit`, `concurrent` +and `IdleCount`](https://docs.gitlab.com/runner/configuration/autoscale.html#how-concurrent-limit-and-idlecount-generate-the-upper-limit-of-running-machines). + +Example: + +```toml +[[runners]] + name = "gitlab-aws-autoscaler" + url = "<URL of your GitLab instance>" + token = "<Runner's token>" + executor = "docker+machine" + limit = 20 +``` + +[Read more](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section) +about all the options you can use under `[[runners]]`. + +### The `runners.docker` section + +In the `[runners.docker]` section you can define the default Docker image to +be used by the child Runners if it's not defined in [`.gitlab-ci.yml`](../../ci/yaml/README.md). +By using `privileged = true`, all Runners will be able to run +[Docker in Docker](../../ci/docker/using_docker_build.md#use-docker-in-docker-executor) +which is useful if you plan to build your own Docker images via GitLab CI/CD. + +Next, we use `disable_cache = true` to disable the Docker executor's inner +cache mechanism since we will use the distributed cache mode as described +in the following section. + +Example: + +```toml + [runners.docker] + image = "alpine" + privileged = true + disable_cache = true +``` + +[Read more](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-docker-section) +about all the options you can use under `[runners.docker]`. + +### The `runners.cache` section + +To speed up your jobs, GitLab Runner provides a cache mechanism where selected +directories and/or files are saved and shared between subsequent jobs. +While not required for this setup, it is recommended to use the distributed cache +mechanism that GitLab Runner provides. Since new instances will be created on +demand, it is essential to have a common place where the cache is stored. + +In the following example, we use Amazon S3: + +```toml + [runners.cache] + Type = "s3" + ServerAddress = "s3.amazonaws.com" + AccessKey = "<your AWS Access Key ID>" + SecretKey = "<your AWS Secret Access Key>" + BucketName = "<the bucket where your cache should be kept>" + BucketLocation = "us-east-1" + Shared = true +``` + +Here's some more info to further explore the cache mechanism: + +- [Reference for `runners.cache`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-cache-section) +- [Deploying and using a cache server for GitLab Runner](https://docs.gitlab.com/runner/configuration/autoscale.html#distributed-runners-caching) +- [How cache works](../../ci/yaml/README.md#cache) + +### The `runners.machine` section + +This is the most important part of the configuration and it's the one that +tells GitLab Runner how and when to spawn new or remove old Docker Machine +instances. + +We will focus on the AWS machine options, for the rest of the settings read +about the: + +- [Autoscaling algorithm and the parameters it's based on](https://docs.gitlab.com/runner/configuration/autoscale.html#autoscaling-algorithm-and-parameters) - depends on the needs of your organization +- [Off peak time configuration](https://docs.gitlab.com/runner/configuration/autoscale.html#off-peak-time-mode-configuration) - useful when there are regular time periods in your organization when no work is done, for example weekends + +Here's an example of the `runners.machine` section: + +```toml + [runners.machine] + IdleCount = 1 + IdleTime = 1800 + MaxBuilds = 10 + OffPeakPeriods = [ + "* * 0-9,18-23 * * mon-fri *", + "* * * * * sat,sun *" + ] + OffPeakIdleCount = 0 + OffPeakIdleTime = 1200 + MachineDriver = "amazonec2" + MachineName = "gitlab-docker-machine-%s" + MachineOptions = [ + "amazonec2-access-key=XXXX", + "amazonec2-secret-key=XXXX", + "amazonec2-region=us-central-1", + "amazonec2-vpc-id=vpc-xxxxx", + "amazonec2-subnet-id=subnet-xxxxx", + "amazonec2-use-private-address=true", + "amazonec2-tags=runner-manager-name,gitlab-aws-autoscaler,gitlab,true,gitlab-runner-autoscale,true", + "amazonec2-security-group=docker-machine-scaler", + "amazonec2-instance-type=m4.2xlarge", + ] +``` + +The Docker Machine driver is set to `amazonec2` and the machine name has a +standard prefix followed by `%s` (required) that is replaced by the ID of the +child Runner: `gitlab-docker-machine-%s`. + +Now, depending on your AWS infrastructure, there are many options you can set up +under `MachineOptions`. Below you can see the most common ones. + +| Machine option | Description | +| -------------- | ----------- | +| `amazonec2-access-key=XXXX` | The AWS access key of the user that has permissions to create EC2 instances, see [AWS credentials](#aws-credentials). | +| `amazonec2-secret-key=XXXX` | The AWS secret key of the user that has permissions to create EC2 instances, see [AWS credentials](#aws-credentials). | +| `amazonec2-region=eu-central-1` | The region to use when launching the instance. You can omit this entirely and the default `us-east-1` will be used. | +| `amazonec2-vpc-id=vpc-xxxxx` | Your [VPC ID](https://docs.docker.com/machine/drivers/aws/#vpc-id) to launch the instance in. | +| `amazonec2-subnet-id=subnet-xxxx` | The AWS VPC subnet ID. | +| `amazonec2-use-private-address=true` | Use the private IP address of Docker Machines, but still create a public IP address. Useful to keep the traffic internal and avoid extra costs.| +| `amazonec2-tags=runner-manager-name,gitlab-aws-autoscaler,gitlab,true,gitlab-runner-autoscale,true` | AWS extra tag key-value pairs, useful to identify the instances on the AWS console. The "Name" tag is set to the machine name by default. We set the "runner-manager-name" to match the Runner name set in `[[runners]]`, so that we can filter all the EC2 instances created by a specific manager setup. Read more about [using tags in AWS](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html). | +| `amazonec2-security-group=docker-machine-scaler` | AWS VPC security group name, see [AWS security groups](#aws-security-groups). | +| `amazonec2-instance-type=m4.2xlarge` | The instance type that the child Runners will run on. | + +TIP: **Tip:** +Under `MachineOptions` you can add anything that the [AWS Docker Machine driver +supports](https://docs.docker.com/machine/drivers/aws/#options). You are highly +encouraged to read Docker's docs as your infrastructure setup may warrant +different options to be applied. + +NOTE: **Note:** +The child instances will use by default Ubuntu 16.04 unless you choose a +different AMI ID by setting `amazonec2-ami`. + +NOTE: **Note:** +If you specify `amazonec2-private-address-only=true` as one of the machine +options, your EC2 instance won't get assigned a public IP. This is ok if your +VPC is configured correctly with an Internet Gateway (IGW) and routing is fine, +but it’s something to consider if you've got a more complex configuration. Read +more in [Docker docs about VPC connectivity](https://docs.docker.com/machine/drivers/aws/#vpc-connectivity). + +[Read more](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-machine-section) +about all the options you can use under `[runners.machine]`. + +### Getting it all together + +Here's the full example of `/etc/gitlab-runner/config.toml`: + +```toml +concurrent = 10 +check_interval = 0 + +[[runners]] + name = "gitlab-aws-autoscaler" + url = "<URL of your GitLab instance>" + token = "<Runner's token>" + executor = "docker+machine" + limit = 20 + [runners.docker] + image = "alpine" + privileged = true + disable_cache = true + [runners.cache] + Type = "s3" + ServerAddress = "s3.amazonaws.com" + AccessKey = "<your AWS Access Key ID>" + SecretKey = "<your AWS Secret Access Key>" + BucketName = "<the bucket where your cache should be kept>" + BucketLocation = "us-east-1" + Shared = true + [runners.machine] + IdleCount = 1 + IdleTime = 1800 + MaxBuilds = 100 + OffPeakPeriods = [ + "* * 0-9,18-23 * * mon-fri *", + "* * * * * sat,sun *" + ] + OffPeakIdleCount = 0 + OffPeakIdleTime = 1200 + MachineDriver = "amazonec2" + MachineName = "gitlab-docker-machine-%s" + MachineOptions = [ + "amazonec2-access-key=XXXX", + "amazonec2-secret-key=XXXX", + "amazonec2-region=us-central-1", + "amazonec2-vpc-id=vpc-xxxxx", + "amazonec2-subnet-id=subnet-xxxxx", + "amazonec2-use-private-address=true", + "amazonec2-tags=runner-manager-name,gitlab-aws-autoscaler,gitlab,true,gitlab-runner-autoscale,true", + "amazonec2-security-group=docker-machine-scaler", + "amazonec2-instance-type=m4.2xlarge", + ] +``` + +## Cutting down costs with Amazon EC2 Spot instances + +As [described by][spot] Amazon: + +> +Amazon EC2 Spot instances allow you to bid on spare Amazon EC2 computing capacity. +Since Spot instances are often available at a discount compared to On-Demand +pricing, you can significantly reduce the cost of running your applications, +grow your application’s compute capacity and throughput for the same budget, +and enable new types of cloud computing applications. + +In addition to the [`runners.machine`](#the-runners-machine-section) options +you picked above, in `/etc/gitlab-runner/config.toml` under the `MachineOptions` +section, add the following: + +```toml + MachineOptions = [ + "amazonec2-request-spot-instance=true", + "amazonec2-spot-price=0.03", + "amazonec2-block-duration-minutes=60" + ] +``` + +With this configuration, Docker Machines are created on Spot instances with a +maximum bid price of $0.03 per hour and the duration of the Spot instance is +capped at 60 minutes. The `0.03` number mentioned above is just an example, so +be sure to check on the current pricing based on the region you picked. + +To learn more about Amazon EC2 Spot instances, visit the following links: + +- https://aws.amazon.com/ec2/spot/ +- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-requests.html +- https://aws.amazon.com/blogs/aws/focusing-on-spot-instances-lets-talk-about-best-practices/ + +### Caveats of Spot instances + +While Spot instances is a great way to use unused resources and minimize the +costs of your infrastructure, you must be aware of the implications. + +Running CI jobs on Spot instances may increase the failure rates because of the +Spot instances pricing model. If the price exceeds your bid, the existing Spot +instances will be immediately terminated and all your jobs on that host will fail. + +As a consequence, the auto-scale Runner would fail to create new machines while +it will continue to request new instances. This eventually will make 60 requests +and then AWS won't accept any more. Then once the Spot price is acceptable, you +are locked out for a bit because the call amount limit is exceeded. + +If you encounter that case, you can use the following command in the bastion +machine to see the Docker Machines state: + +```sh +docker-machine ls -q --filter state=Error --format "{{.NAME}}" +``` + +NOTE: **Note:** +There are some issues regarding making GitLab Runner gracefully handle Spot +price changes, and there are reports of `docker-machine` attempting to +continually remove a Docker Machine. GitLab has provided patches for both cases +in the upstream project. For more information, see issues +[#2771](https://gitlab.com/gitlab-org/gitlab-runner/issues/2771) and +[#2772](https://gitlab.com/gitlab-org/gitlab-runner/issues/2772). + +## Conclusion + +In this guide we learned how to install and configure a GitLab Runner in +autoscale mode on AWS. + +Using the autoscale feature of GitLab Runner can save you both time and money. +Using the Spot instances that AWS provides can save you even more, but you must +be aware of the implications. As long as your bid is high enough, there shouldn't +be an issue. + +You can read the following use cases from which this tutorial was (heavily) +influenced: + +- [HumanGeo - Scaling GitLab CI](http://blog.thehumangeo.com/gitlab-autoscale-runners.html) +- [subtrakt Health - Autoscale GitLab CI Runners and save 90% on EC2 costs](https://substrakthealth.com/news/gitlab-ci-cost-savings/) + +[spot]: https://aws.amazon.com/ec2/spot/ |