Jordan Taylor
justjordant

justjordant

Day 4 - Pulumi Stacks

Day 4 - Pulumi Stacks

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Jordan Taylor
·May 1, 2022·

5 min read

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Table of contents

Pulumi stacks

Why do we want to manage a Stack?

A new project can have as many stacks as you need. By default, Pulumi creates a stack for you when you start a new project using the pulumi new command.

Pulumi program is deployed to a stack. A stack is an isolated, independently configurable instance of a Pulumi program. Stacks are commonly used for different phases of development (such as development, staging, and production) or feature branches (such as feature-x-dev); we could even use stacks from a different region standpoint (as in centralus, easteu.

Managing stacks can help us manage different environments within our cloud infrastructures, and easier deployments since everything for a given stack (environments) has been configured via stack files. ie Pulumi.dev.yaml; these are also containers for the state of our infrastructure.

image.png

How can we manage a Stack?

Create a new stack.

We can create a new stack in pulumi with the following.

pulumi stack init staging.

This will create the stack with the name staging, and set this to the active stack. Based on the pulumi documentation the project that the stack is associated with is determined by finding the nearest Pulumi.yaml file.

Side Note: The pulumi stack init stackName CLI command will not create the stack configuration file, you will need to configure this manually by creating the file and adding the need yaml required configuration for your stack, or you can us the pulumi CLI to make this for you by using the config set command.

pulumi config set azure-native:location CentralUS

We can think of these as Key:Values pairs CentralUS is just a value to location we can use this to add any type of variables that we will need in our stacks.

Listing stacks in a project.

We can list the current stacks that we have in our project by using the pulumi stack ls.

pulumi stack ls
NAME      LAST UPDATE  RESOURCE COUNT  URL
dev       n/a          n/a             https://app.pulumi.com/JustJordanT/azure-csharp/dev
staging*  n/a          n/a             https://app.pulumi.com/JustJordanT/azure-csharp/staging

Viewing the output we see that we have two stacks available to us; The * shows the current that is selected.

  • The NAME shows the name of the stacks.
  • LAST UPDATE shows the last time the stack was updated.
  • RESOURCE COUNT show how many resources we currently have in each stack.

Selecting a stack.

Using pulumi stack select we can change the active stack.

pulumi stack select

Please choose a stack, or create a new one:  [Use arrows to move, enter to select, type to filter]
> dev
  staging
  <create a new stack>

Side Note: The pulumi operations config, preview, update and destroy operate on the active stack.

Generate an update plan.

We can use the pulumi preview --save-plan=planName.json to save the output to a file; this will use the current Configuration values that we have in place for this stack.

![[Pasted image 20220424211507.png]]

Update a stack.

Update our selected stack, by running pulumi up. If you saved a plan from a preview you can pass that in to constrain the update to only doing what was planned with pulumi up --plan=plan.json. The operation uses the latest configuration values) for the active stack.

Viewing Stack Resources.

Running the pulumi stack, will show us the current, stack resources and stats. a good way to see the correct resources, and outputs.

pulumi stack
Current stack is dev:
    Last updated 1 week ago (2022-03-02 06:26:09 -0800 CST)
    Pulumi version v3.0.0

Current stack resources (3):
    TYPE                                             NAME
    pulumi:pulumi:Stack                              webserver-dev
    aws:ec2/securityGroup:SecurityGroup              web-secgrp
    aws:ec2/instance:Instance                        web-server-www

Current stack outputs (2):
    OUTPUT                                           VALUE
    publicDns                                        ec2-18-218-85-197.us-east.com
    publicIp                                         20.215.88.199

Stack tags.

We can use tags just like we do on our cloud providers, we are able to separate environments based on the tags from prod, dev, staging, and so on.

Side Note: We are only able to use tags if we are managing our state with the pulumi backend. i.e pulumi cloud

 pulumi stack tag ls
NAME                VALUE
gitHub:owner        60DaysOf
gitHub:repo         60-days-of-pulumi
pulumi:description  A minimal Azure Native C# Pulumi program
pulumi:project      azure-csharp
pulumi:runtime      dotnet
vcs:kind            github.com
vcs:owner           60DaysOf
vcs:repo            60-days-of-pulumi

Stack outputs.

Outputs can be used by calling these out in our code; here is an example of this below.

import * as pulumi from "@pulumi/pulumi";
import * as docker from "@pulumi/docker";

const stackName = pulumi.getStack()

// Find the latest Ubuntu precise image.
const ubuntuRemoteImage = new docker.RemoteImage("ubuntuRemoteImage", {name: "ubuntu:precise"});

// Create a network

const network = new docker.Network("network", {name: `network-${stackName}`})

// Outputs

export let imageName = ubuntuRemoteImage.name
export let imageId = ubuntuRemoteImage.id
export let networkName = network.name

We can see here at the end of the typescript file we can some outputs that we have created.

Using the following pulumi cli commands, we can pull these output values.

pulumi stack output imageName
ubuntu:precise

Stack References.

With stack references, we can access outputs from one stack to another. This can allow us to output certain information that will need in another stack, or even a different pulumi project together.

To reference values from a stack, we create a stack reference from within our source code so that we can call this by name.

var dockerCsharp = new StackReference("JustJordant/docker-csharp/dev");
var csharpContainerImageName = dockerCsharp.GetOutput("imageName");

From here, we would be able to pass this output throughout our project and use it as needed.

Importing and exporting stacks

A stack can be Imported and Exported; when we do this, we are handling the state of our stacks. We can export our stack before changing our state to have an excellent baseline to return to; then, we can import our stack back to a good state.

Example:

pulumi stack export --file stack-bak.json

pulumi stack import --file stack-bak.json

Destroy and Deleting Stacks.

Before we delete a stack, we need to make sure that we have no resources in it. Then, we can delete a stack. This is best practice!

pulumi destroy

pulumi stack

If we want to force the deletion, we can, but this will leave those non-deleted resources in an unmanaged state by pulumi.

pulumi stack rm --force.

What does managing a Stack do for us?

Managing Stacks enables us to have our different environments and via stacks prod, dev, staging; this way, we can architect this is in various ways to build our stacks/environment that will be more manageable from the infrastructure side of the house.

Resources.

Happy coding, My Friends!

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