service-training

This project is the training material for the service repo broken out into steps.

Requirements

This project was designed against Go 1.12. It should work for 1.11 but 1.12 is recommended.

Supporting services like the database are hosted in Docker. If you cannot install Docker on your machine you can still follow most of this material by hosting a database elsewhere and modifying the connection information to your needs.

Setup

Clone this repository somewhere on your computer. The location does not especially matter but if it is outside of your $GOPATH then the Go modules features will work automatically.

In a separate folder make a directory where you will be building your API. We recommend you initialize that folder as a Git repository to track your work.

mkdir ~/training
cd ~/training
git clone https://github.com/ardanlabs/service-training.git
mkdir garagesale
cd garagesale
git init .

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You must also use go mod init to set the import path for this project. Doing this exactly as shown will allow you to copy and paste code without a need to modify import paths.

go mod init github.com/ardanlabs/garagesale
git add go.mod
git commit -m "Initial commit"

Postman API Client

For the class we will be building up a REST API. You may use any HTTP client you prefer to make requests but we recommend Postman. For convenience you may use the import button in the top left to import the included postman_environment.json and postman_collection.json files to get a client up and running quickly. Be sure to select the "Garage Sale Service" environment in the top right.

Diffing Folders

Reviewing the differences between the successive steps helps to reinforce the ideas each change is about. This is made easier by running the following command to define a git alias called dirdiff:

git config --global alias.dirdiff 'diff -p --stat -w --no-index'

With that alias in place, run this command from the top level folder to see the differences between the 01-startup directory and the 02-shutdown directory.

git dirdiff 01-startup 02-shutdown`

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Maintenance of this project

This section is only relevant to maintainers of this repository.

Many of the commands in this section rely on a shell feature that converts expressions like **/*.go to a list of all .go files under the current directory, recursively. Test this by running echo **/*.md. If it shows a list of all Markdown files then your shell supports it. If it shows the literal string **/*.md then the feature is not enabled. Add shopt -s globstar to your shell init file and try again.

Applying changes

Whenever a change is made to service it needs to be backported to this repository. Find the step folder where the affected features were introduced, make the changes, then copy them forward through to the last step.

Before making changes I recommend using the md5c tool to visualize the different steps of evolution a particular file has through the project. For example run md5c **/web/web.go to see where the web.go file is introduced and which steps modify it.

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If you modify a file in an early step and multiple subsequent steps are identical you can copy the file forward without manually applying the changes. For example if you change web.go in step 13 and want to apply the same changes to steps 14 through 23 you can run this

for f in {14..23}*/**/web.go; do cp 13*/**/web.go $f; done

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When applying changes between files that are not identical you must manually copy only the relevant lines. This may involve merging two different lines together if a newer step already changed the affected line. I recommend using a diffing program. I use vimdiff but you can use any diffing tool that feels comfortable.

vimdiff {32..33}*/internal/user/user.go

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After bringing changes all the way forward you should rerun the md5c and compare it with the original output. The output will be different but in most cases the pattern of colors should be the same.

Regenerating Docs

Be sure to regenerate the File Lists of the READMEs after every change. Reviewing these changes to the READMEs can help validate that you didn't miss a step.

./scripts/file_lists.sh

Adding New Folders

If needed, you can insert a whole new step folder in the middle of these materials. For example if you wanted to add a "ready check" section after folder 22-health you would need to bump the folder numbers for steps 23+ then copy folder 22 to become the new 23.

There is a script to assist in this so for the example case I would do this:

for dir in {23..36}*; do ./scripts/bump.sh $dir; done
cp -a 22-health 23-readycheck

But really please don't insert folders in the middle. If it is reasonable just add a new section to the end by copying the newest folder.

cp -a 36-self-shutdown 37-new-thing

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Synchronizing Changes

Use git dirdiff against the service repo periodically to look for major changes. To reduce noise you can change all of the imports in this project to match the other. Be sure to have a clean git status before you do the diff so you can quickly revert the changes.

sed -i "" -e "s/garagesale/service/" **/*.go
git dirdiff {service,.}/cmd
git checkout -- **/*.go