109 lines
5.4 KiB
Markdown
109 lines
5.4 KiB
Markdown
# Overview - General
|
|
|
|
|
|
## Objective
|
|
Whenever a PR job is run on the CI infrastructure (e.g. CircleCI), we want to build `angular.io`
|
|
and host the build artifacts on a publicly accessible server so that collaborators (developers,
|
|
designers, authors, etc) can preview the changes without having to checkout and build the app
|
|
locally.
|
|
|
|
|
|
## Source code
|
|
In order to make it easier to administer the server and version-control the setup, we are using
|
|
[docker](https://www.docker.com) to run a container on a VM. The Dockerfile and all other files
|
|
necessary for creating the docker container are stored (and versioned) along with the angular.io
|
|
project's source code (currently part of the angular/angular repo) in the `aio-builds-setup/`
|
|
directory.
|
|
|
|
|
|
## Setup
|
|
The VM is hosted on [Google Compute Engine](https://cloud.google.com/compute/). The host OS is
|
|
debian:jessie. For more info how to set up the host VM take a look at the "Setting up the VM"
|
|
section in [TOC](_TOC.md).
|
|
|
|
|
|
## Security model
|
|
Since we are managing a public server, it is important to take appropriate measures in order to
|
|
prevent abuse. For more details on the challenges and the chosen approach take a look at the
|
|
[security model](overview--security-model.md).
|
|
|
|
|
|
## The 10000 feet view
|
|
This section gives a brief summary of the several operations performed on CI and by the docker
|
|
container:
|
|
|
|
|
|
### On CI (CircleCI)
|
|
- The CI script builds the angular.io project.
|
|
- The CI script gzips and stores the build artifacts in the CI infrastructure.
|
|
- When the build completes, CircleCI triggers a webhook on the preview-server.
|
|
|
|
More info on how to set things up on CI can be found [here](misc--integrate-with-ci.md).
|
|
|
|
|
|
### Hosting build artifacts
|
|
- nginx receives the webhook trigger and passes it through to the preview server.
|
|
- The preview-server runs several preliminary checks to determine whether the request is valid and
|
|
whether the corresponding PR can have a (public or non-public) preview (more details can be found
|
|
[here](overview--security-model.md)).
|
|
- The preview-server makes a request to CircleCI for the URL of the AIO build artifacts.
|
|
- The preview-server makes a request to this URL to receive the artifact - failing if the size
|
|
exceeds the specified max file size - and stores it in a temporary location.
|
|
- The preview-server runs more checks to determine whether the preview should be publicly accessible
|
|
or stored for later verification (more details can be found [here](overview--security-model.md)).
|
|
- The preview-server changes the "visibility" of the associated PR, if necessary. For example, if
|
|
builds for the same PR had been previously deployed as non-public and the current build has been
|
|
automatically verified, all previous builds are made public as well.
|
|
If the PR transitions from "non-public" to "public", the preview-server posts a comment on the
|
|
corresponding PR on GitHub mentioning the SHAs and the links where the previews can be found.
|
|
- The preview-server verifies that it is not trying to overwrite an existing build.
|
|
- The preview-server deploys the artifacts to a sub-directory named after the PR number and the
|
|
first few characters of the SHA: `<PR>/<SHA>/`
|
|
(Non-publicly accessible PRs will be stored in a different location, but again derived from the PR
|
|
number and SHA.)
|
|
- If the PR is publicly accessible, the preview-server posts a comment on the corresponding PR on
|
|
GitHub mentioning the SHA and the link where the preview can be found.
|
|
|
|
More info on the possible HTTP status codes and their meaning can be found
|
|
[here](overview--http-status-codes.md).
|
|
|
|
|
|
### Updating PR visibility
|
|
- nginx receives a natification that a PR has been updated and passes it through to the
|
|
preview-server. This could, for example, be sent by a GitHub webhook every time a PR's labels
|
|
change.
|
|
E.g.: `ngbuilds.io/pr-updated` (payload: `{"number":<PR>,"action":"labeled"}`)
|
|
- The request contains the PR number (as `number`) and optionally the action that triggered the
|
|
request (as `action`) in the payload.
|
|
- The preview-server verifies the payload and determines whether the `action` (if specified) could
|
|
have led to PR visibility changes. Only requests that omit the `action` field altogether or
|
|
specify an action that can affect visibility are further processed.
|
|
(Currently, the only actions that are considered capable of affecting visibility are `labeled` and
|
|
`unlabeled`.)
|
|
- The preview-server re-checks and if necessary updates the PR's visibility.
|
|
|
|
More info on the possible HTTP status codes and their meaning can be found
|
|
[here](overview--http-status-codes.md).
|
|
|
|
|
|
### Serving build artifacts
|
|
- nginx receives a request for a hosted preview resource on a subdomain corresponding to the PR and SHA.
|
|
E.g.: `pr<PR>-<SHA>.ngbuilds.io/path/to/resource`
|
|
- nginx maps the subdomain to the correct sub-directory and serves the resource.
|
|
E.g.: `/<PR>/<SHA>/path/to/resource`
|
|
|
|
More info on the possible HTTP status codes and their meaning can be found
|
|
[here](overview--http-status-codes.md).
|
|
|
|
|
|
### Removing obsolete artifacts
|
|
In order to avoid flooding the disk with unnecessary build artifacts, there is a cronjob that runs a
|
|
clean-up task once a day. The task retrieves all open PRs from GitHub and removes all directories
|
|
that do not correspond to an open PR.
|
|
|
|
|
|
### Health-check
|
|
The docker service runs a periodic health-check that verifies the running conditions of the
|
|
container. This includes verifying the status of specific system services, the responsiveness of
|
|
nginx and the preview-server and internet connectivity.
|