2aeebcda5a
Co-authored-by: Mac Siri <krairit.siri@gmail.com> Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>
87 lines
4.4 KiB
Markdown
87 lines
4.4 KiB
Markdown
---
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title: Deployment and CI/CD Process
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---
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# Deployment and CI/CD Process
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## Overview
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DEV relies on GitHub and Travis to deploy continuously to Heroku. If a Pull
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Request is merged with a `[deploy]` in its title, it will be automatically
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deployed to production once the build steps complete successfully. The process
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currently takes about 20 minutes to complete and will need a few additional
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minutes before the change goes live.
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## Travis Stages
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The following stages can be explored in our
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[.travis.yml](https://github.com/thepracticaldev/dev.to/blob/master/.travis.yml)
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and [Procfile](https://github.com/thepracticaldev/dev.to/blob/master/Procfile).
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Our Travis CI process consists of 2 stages.
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1. Running our test suite in 3 parallel jobs.
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2. Deploying the application if we have merged with the master branch and the
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`[deploy]` flag is present in the merge commit.
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### Stage 1: Running Tests
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In stage 1, we use [KnapsackPro](https://knapsackpro.com/) to divide our Rspec
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tests evenly between 3 different jobs (virtual machines). This ensures that each
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job takes relatively the same amount of time to run. After running our Rspec
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tests, we then run a series of other checks. These additional checks are split
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up between the different jobs. Here is a list of those additional checks that
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are run.
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- Job 0 is where we run Javascript tests, Preact tests, and coverage checks.
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- Job 1 is where Travis builds Storybook to ensure its integrity, and where we check for any known vulnerabilities using `bundle-audit`.
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- Job 2 is where Travis fires up a Rails console to ensure the application loads properly, and where specs with KnapsackPro are run.
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If all of the jobs pass then we move on to Stage 2 of the Travis CI process.
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### Stage 2: Deploying
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If the build was kicked off from a pull request being created or updated this
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stage will do nothing. If the branch has been merged into master with the
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`[deploy]` flag, then this stage will kick off a deploy. The deploy will run in
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its own job deploying our application to Heroku.
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Prior to deploying the code, Heroku will run database migrations, Elasticsearch
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updates, and do some final checks (more information on that below) to make sure
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everything is working as expected. If these all succeed, then the deploy
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completes and our team is notified.
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## Deploying to Heroku
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We use Heroku's
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[Release Phase](https://devcenter.heroku.com/articles/release-phase) feature.
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Upon deploy, the app installs dependencies, bundles assets, and gets the app
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ready for launch. However, before it launches and releases the app Heroku runs a
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release script on a one-off dyno. If that release script/step succeeds the new
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app is released on all of the dynos. If that release script/step fails then the
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deploy is halted and we are notified.
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The name of the script we use is `release-tasks.sh` and its in our root
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directory. During this release step we do a few checks.
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1. We first check the DEPLOY_STATUS environment variable. In the event that we
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want to prevent deploys, for example after a rollback, we will set
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DEPLOY_STATUS to "blocked". This will cause the release script to exit with a
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code of 1 which will halt the deploy. This ensures that we don't accidentally
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push out code while we are waiting for a fix or running other tasks.
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2. We run any outstanding migrations. This ensures that a migration finishes
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successfully before the code that uses it goes live.
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3. We run any data update scripts that need to be run. A data update script is
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one that allows us to update data in the background separate from a
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migration. For example, if we add a new field to Elasticsearch and need to
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reindex all of our documents we would use a data update script.
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4. We update Elasticsearch. Elasticsearch contains indexes which have mappings.
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Mappings are similar to database schema. The same way we run a migration to
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update our database we have to run a setup task to update any Elasticsearch
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mappings.
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5. Following updating all of our datastores we use the Rails runner to output a
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simple string. Executing a Rails runner command ensures that we can boot up
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the entire app successfully before it is deployed. We deploy asynchronously,
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so the website is running the new code a few minutes after deploy. A new
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instance of Heroku Rails console will immediately run a new code.
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