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Version: 4.5

Rust

Rust Application Stack​

The rust application stack is used to build and deploy rust applications and produce deployment-ready containers for the SCALE environment. The containers produced in this application stack share common requirements with other application stacks deployed to the SCALE environment. These shared requirements include:

  • Security scanning for any vulnerabilities
  • Code coverage scanning for test quality.
  • Staging of the application container in the appropriate Docker container repositories and tagged according to SCALE conventions.
  • Completion of Unit Testing and User Acceptance Testing
  • Gated approvals before allowing deployments into pre-production and production environments.
  • Audit trail and history of deployment within the SCALE CI/CD Pipeline

Because of the above-listed requirements, rust application stack is provided in order to support the build and deployment of rust applications in a manner that integrates with SCALE requirements and processes. The flow of deployment includes first a Continuous Integration stage of processing in a pipeline prior to deployment in the Continuous Deployment stages. The Continuous Integration stage focuses on building the application, running scans to check for test coverage and security vulnerabilities, and staging the container in the appropriate Docker repository ready for deployment. Subsequent pipeline stages deploy the application to the appropriate target Kubernetes spaces.

Getting Started in the Azure DevOps environment​

Refer to the following link to learn about getting started in the Azure DevOps environment: Getting Started in Azure DevOps Environment

Source Code Repository Structure​

The structure of the source code repository for rust application stack will contain a source directory tree with the application source code, and one or two directory trees with details for deployment, as follows:

  • source - this directory contains boilerplate code creating rust 'hello-SCALE' boilerplate application.
  • appCode-serviceName - (named as the AppCode followed by the application or service name) contains the Helm chart required for application deployment on kubernetes clusters (this is the default)

Also at the top of the repository is a file called azure-pipelines.yml. This file contains reference to the appropriate version of the CI/CD pipeline logic, some variables unique to the application (e.g. container version) as well as YAML data structures providing key information about the environments into which to deploy the application and the sequence of events to complete the deployment (e.g. dependencies, additional steps to retrieve secrets to be passed to the deployed container etc).

Additional items in this repository will generally not be modified and should not be changed to avoid risk of breaking the pipeline workflows.

Application Configuration into the SCALE CI/CD Pipeline​

Once navigated to the appropriate repository, it can be cloned to a local development environment (i.e. local workstation) for the actual application development and configuration work for the rust application to be deployed. Configuration of the pipeline would include setting the appropriate container version (reflected in the appVersion variable under the parameters: section) and defining the target workspace and hostspaces plus any dependencies between hostspaces or prerequisite deployment objects required. Once it is ready to be deployed into the SCALE workspace and the new application version has been set as well, create a Git pull request for the updates to the code. The creation of this pull request will trigger the Continuous Integration pipeline to start.

Continuous Integration and Continuous Delivery Pipelines​

Please note that the document "SCALE Concepts and Procedures" contains more details about the specific flow of the application through the CI/CD pipelines

Once a pull request has been created against master branch, it will trigger the start of the CI/CD pipeline in order to build, scan and prepare the application for deployment into the Workspace. Although the CI/CD pipeline flow is automatically triggered, there are times when it needs to be manually run (or re-run) and the pipeline should be examined for the results of its preparation of the application and deployments. Details for examining the CI/CD pipeline and analyzing its results can be found here: Continuous Integration and Continuous Delivery Pipelines

Upgrading to Pipeline v4.7​

SCALE DevOps Pipeline v4.7 introduces CyberArk Integration with Rancher. Conjur performs certificate-based authentication with each Rancher cluster and securely supplies secrets to each namespace/application within the cluster. Secrets are securely stored in the CyberArk vault. For more information refer Conjur Integration Document.

  1. Setup CyberArk integration (link)

  2. Remove ambassador.yaml file from templates folder.

  3. Add release 4.7 referance in azure-pipelines.yaml.

resources:
  repositories:
  - { repository: templates, type: git, name: devexp-engg/automation, ref: release/v4.7 }
  - { repository: spaces, type: git, name: spaces, ref: devops/v1.0 }

Note : Security scan stage was release as a minor update in v4.5 to read more about how this feature works please refer [New Security Stage of Pipeline: CrowdStrike Image Scanning and Gitleaks Secret Scanning](../references/security-pipeline.md).

To transition to v4.7, we recommend using the dxpctl tool. - Access the latest tool here

Downloadable Version Docker Build/Run Locally

Why Rust?​

Rust is blazingly fast and memory-efficient: with no runtime or garbage collector, it can power performance-critical services, run on embedded devices, and easily integrate with other languages. Rust's rich type system and ownership model guarantee memory-safety and thread-safety - enabling you to eliminate many classes of bugs at compile-time. Rust has great documentation, a friendly compiler with useful error messages, and top-notch tooling - an integrated package manager and build tool, smart multi-editor support with auto-completion and type inspections, an auto-formatter, and more.

Cargo​

Rust applications are generally powered by Cargo: Rust package manager. Cargo downloads your Rust package's dependencies, compiles your packages or binaries and can make distributable packages. SCALE Rust appstack requires mandatory Cargo.toml file that contains rust application metadata including name, dependencies or dev-dependencies etc. See more keys and their definitions at Manifest Format. Please refer to The Cargo Book for further reading. Visit Rust community's crate registry crates.io for available crates.

Appplication Code​

Source directory contains source code for the rust application. Apart from Cargo.toml file, sub-directory src is requied which contains application rust (*.rs) files and unit tests. Integration tests in case of complex application should be organized in saperate tests directory. Please refer to official documentation for recommended project structure. Boiler plate Hello-SCALE demostartes simplest example of actix-web framework.

Pipeline Definition: azure-pipelines.yml file​

The logic for the rust CI/CD pipeline is a common and shared code base for all applications; however the configuration of the pipeline that applies the common logic to the specific application is defined in the top level directory of the source code repository for the application in a file named azure-pipelines.yml.

The structure of the azure-pipelines.yml file is a YAML file using standard YAML syntax. For general information about YAML structures, there are many available resources, including the tutorial at this link: YAML Tutorial.

There are certain required data elements that must be defined within the azure-pipelines.yml file as a prerequisite to the CI/CD pipeline running while other elements are optional and used to modify the standard behavior or the CI/CD pipeline.

More details about the azure-pipelines.yml file can be found here: General Structure of the azure-pipelines.yml File

Configuration which refers the logic for V4 pipeline for the rust application, repo & branch can configure under resources/repositories variable

resources:
  repositories:
    - { repository: templates, type: git, name: devexp-engg/automation, ref: release/v4.7 }
    - { repository: spaces, type: git, name: spaces, ref: devops/v1.0 }

Application-Specific Pipeline Configuration​

The extends YAML object is a complex object consisting of additional YAML objects. This object is used to extend the pipeline logic (referenced by the repository defined in the resources object) by (a) referencing the correct appstack pipeline entry point and (b) passing a set of YAML objects as parameters to influence the behavior of the pipeline to meet an application teams specific needs.

The extends YAML object consists of 2 objects beneath it:

  • template
  • parameters

The template YAML object is a single value set to the initial entry point for the v4.7 pipeline for the rust appstack, so it should always be defined as follows:

extends:
  template: devops/rust.yml@spaces

Please refer to upgrade document to know more about rust.yml@templates which holds required metadata for the pipeline.

The parameters YAML object is defined immediately following the template object and at the same indentation level. This is the object that requires the most attention and definition to be set up. The parameters YAML object includes multiple parameters which can be used to configure CI/CD pipeline. Primarily this object contains parameters used for application builds. A typical setting in here would be to define appVersion used to build the application, looking like the following (including all of the extends object preceding it):

extends:
  template: devops/rust.yml@spaces
  parameters:
    appVersion: 4.7.x

Code style and testing​

Application build process runs rustfmt tool via cargo to verify quality Rust application code formatting according to style guidelines. Further runs all defined tests and calculates code coverage with cargo-tarpaulin. You can control style checks and tests in azure-pipelines.yaml.

parameters:
  appVersion: 4.7.x
  rustfmt: "true"
  cargotest: "true"

Though both the options are configurable it is strongly recommended not to set rustfmt and cargotest parameters unless absolutely nessesary.

SCALE Pipeline runs cargo build in release mode to achive optimal run time performance. To know more about optimized artifacts with the release profile see the profiles section.

Rust version​

The rust default version used by SCALE pipeline is Rust 1.84.1. Optionally you can specify it as a parameters in azure-pipelines.yaml:

  parameters:
    appVersion: 4.7.0
    rust:
      version: "1.84.1"
      tarpaulinVersion: "0.31.5"

Official debian rust images are used to build the application but images could be bulky for running the built application itself. SCALE recommends a practice to use a multibuild docker setup where the executable is created in a builder step and then copied into a different, slimmer image. For example, default rust toolchain image used in the SCALE pipeline to compile and build the application is rust:1.50-buster and later during docker build copies application binary into base image debian:buster-slim to build much slimmer final image for faster deployments. For most of applications use cases just specifying rust version should be sufficient. (For advanced users: Both baseImage and toolchainImage can be configured in azure-pipelines.yaml if required.)

Defining hostspaces for application deployment​

Pipeline 4.7 simplifies the structure of azure-pipelines.yml to define all spaces(workspace,devint,db/hostspaces) as a single list. Older format is still supported but to continue using old format ref and k8s must be removed from spaces. It's strongly recommended to follow newer format. acceptanceSpace must be specified in the file. For example:

parameters:
  acceptanceSpace: devexp-ae103-stg
  spaces:
    workspace:
      helm:
        overrideFiles: |
          devexp-rust/values.workspace.yaml
    devexp-ae101-dnt:
      helm:
        overrideFiles: |
          devexp-rust/values.hostspace.yaml
    devexp-ae103-stg:
      helm:
        overrideFiles: |
          devexp-rust/values.hostspace.yaml
    devexp-npc02-prd:
      helm:
        overrideFiles: |
          devexp-rust/values.hostspace.yaml

Skipping deployments​

It's a new handy feature introduced in v4.x pipeline. During initial builds or testing, deployments can be excluded for all spaces (workspace,devint,db/hostspaces) even if configured in azure-pipelines.yaml. Pipeline will only perform application build and scans.

extends:
  template: devops/rust.yml@spaces
  parameters:
    system:
      skipDeploy: true

Horizontal Pod Auto-scaler​

Pipeline v4.7 includes configuration of Horizontal Pod Auto-scaling for any deployment. Please refer to documentation for more details. To configure HPA use below template in values.yaml for the host space required. Below commented example starts the deployment with a single pod which can be scaled up to 3 pods when avarage cpu usage crossed 70%.

# If you are using Horizontal POD Auto Scaler, you must disable ReplicaCount
replicaCount: 2

# hpa:
#   min: 1
#   max: 3
#   cpu: 70

PVC for application stacks​

Persistent Volume Claims (PVCs) for application stacks involve providing support for persistent storage in application stacks deployed in Kubernetes clusters. By enabling PVCs for application stacks, This feature will allow developers to define and configure persistent storage requirements for their applications using PVCs.

persistence:
  - enabled: true
    name: data
    #storageClass: ""
    accessMode: ReadWriteMany
    # subPath: appdata
    size: 25Gi
    mountPath: /data

DR changes​

With the introduction of pipeline v4.7, we have implemented DR capabilities that require changes in the Helm chart. Please refer to the document below for the necessary modifications and kindly update your Helm chart accordingly.

DR Prerequisites (V4.4)

Please refer to the following document to prepare your codebase for disaster recovery.

DR Manual Upgrade (V4.4)

Pod Anti-Affinity​

Pipeline v4.7 enchances pod scheduling on the cluster with addition of Pod Anti-affinity. For multi-pod applications, this ensures pod scheduled scattered across the nodes within a cluster.

Detailed Pipeline Configuration​

The remainder of the configuration work in the azure-pipelines.yml file focuses primarily on defining the target workspace and hostspaces for the rust application and providing details for these spaces, any additional tasks needed to prepare the deployments, and dependencies that will dictate the sequence of deployments in these spaces beyond the established SCALE environment deployment approval processes. Details for configuring these elements of the pipeline can be found here: Pipeline Configuration Details

Kubernetes Deployment Objects​

In order to deploy an application number of Kubernetes objects must be defined and deployed. The definition of these objects is controlled through a set of files in one of two forms: Either as Helm charts (the default method) or as Kustomize files (a newer form of deployment description which has limited support in V3.5). Information about the contents and customization of these Kubernetes deployment objects can be found here: Kubernetes Deployment Objects

Troubleshooting​

If something fails to deploy, the information about why the deployment failed (or was not even initiated) will be found in the logs of the CI/CD pipeline and can be tracked down using the methods described earlier in the "Continuous Integration and Continuous Delivery Pipelines" section.

However, additional information may be required either to better troubleshoot a failed deployment or to investigate the runtime behavior of an application that has been successfully deployed. In those cases, much of the information can be found in the Rancher web console. Information about navigating and analyzing information from the Rancher web console can be found here: Navigating the Rancher Web Console