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Turja Narayan Chaudhuri
Turja Narayan Chaudhuri

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A CI/CD Pipeline using git and Travis CI for a serverless app based on SAM and C#

Notification 1 : All code related to this blog can be found at

So , I had really enjoyed creating a serverless app in AWS based on AWS SAM and deploying it to my AWS account .

You can find all details at -

However  , I wanted to take it a step further . I wanted to create a CI/CD pipeline so that every time I commit any changes to my serverless app on git , it would be automatically deployed to AWS using a build/delivery pipeline.

So , What should we do?

As usual , I first googled to see what other developers were using . I found that TravisCI was obviously very popular in the open source world.

"Travis CI is a hosted, distributed continuous integration service used to build and test software projects hosted at GitHub. Open source projects may be tested at no charge via Private projects may be tested at on a fee basis."

I found a few blog posts on how to set up a CI/CD pipeline using Git and Travis CI but all of them were for NodeJS apps ,and none of them suited my exact use case . So , I decided to work on it on my own.

How to get started?

The assumption here is that we have a fully tested Serverless app based on the SAM template that can be individually deployed using SAM CLI , and we just want to hook it up to some sort of continuous integration pipeline .

Ok, so let's get started.

Sign in to TravisCI with your GitHub account . The service will automatically retrieve all your public repositories from GitHub and display them in a list like this :

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Enable the radio button next to the repo that you want to configure with TravisCI , and click on that repo to navigate to the TravisCI details page . This page shows the details of the builds , their status and so on . TravisCI is designed to seamlessly integrate with Github.

Gotcha 1: Just after configuring TravisCI to work with your repo , you will find that the details page is empty . It might feel like you have misconfigured something , but actually , nothing will happen unless the git repo has a .travis.yml file . As soon as the .travis.yml file is pushed into git , automatic build will start.

What is .travis.yml ?

This is the yaml file that TravisCI uses to start your builds . It is basically a series of steps that guides TravisCI as to what process to follow to build and finally deploy your artifacts. It needs to be present at the root of your project . You can essentially think of it as a script containing the same commands that you otherwise used yourself to deploy the app from your personal machine.

My .travis.yml file looks like this , I have added comments to make it easier to understand.

# this is the language of the solution . i am using csharp
language: csharp
mono: none
# here we tell the version of dotnet sdk that the app uses
dotnet: 2.0
# here we identify the solution that needs to be built
solution: S3ToDynamo.sln
# this tells that only updates in master branch will be considered for build
  only: master
# here we need to install all our dependencies to enable the future steps
- pip install --user awscli
- pip install --user aws-sam-cli
# here the commands needed to build the solution are provided
- dotnet restore
- dotnet publish
- sam validate --template template.json
- sam package --template-file template.json --s3-bucket aws-sam-test-1 --output-template-file serverless-output.yaml
# here the commands needed to deploy the solution are provided
  provider: script
  script: sam deploy --template-file serverless-output.yaml --stack-name aws-sam-trial-1 --capabilities CAPABILITY_IAM
  skip_cleanup: true
    branch: master
    on_failure: always
# here we provide the variables that are set globally for the build+deploy
  - AWS_DEFAULT_REGION=ap-south-1
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Gotcha 2: One important thing to keep in mind to get any sort of CI/CD pipeline running is you need to understand the premise of the setup you are running . CI/CD pipelines are nothing but glorified build and deploy servers (simplistically speaking) . Whenever a build is triggered (say via a source control push) , the CI/CD framework simply downloads the source code from the source control repo into a blank VM(say running Linux) . So , we need to keep in mind that the server will not have many of the packages/dependencies that we otherwise take for granted . That is why in the .travis.yml file you need to specify everything that is needed , even the bare-metal installations that you might take for granted .

For example , in my .travis.yml file , we mentioned

pip install --user awscli
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This step is not needed every time in your local build process , but it is needed for TravisCI as the server where the build is running is simply a blank canvas.

Gotcha 3: In case of AWS deployments , one crucial thing we need is AccessKeyID and SecretAccessKey and the region we need to deploy the solution to . In the above .travis.yml you can see the AWS_DEFAULT_REGION has been set . However , AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are not mentioned there . Then , how will TravisCI deploy to AWS without this vital information ?

This is because I had setup secure parameters/variables from the TravisCI console . This can be done using the settings section of the GitHub repo in the TravisCI . I believe this is a good practice , since , the .travis.yml file will be a part of your public git repo , and exposing secrets in a source control is a very bad practice.

Screenshot showing the Environment Variables section of the TravisCI page.

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All done , now what?

As soon as the .travis.yml file is pushed into the git repo , in a minute or two a build will start in TravisCI console . You can check the logs there to monitor what is happening in the build .

If the .travis.yml file is well written , and the project builds properly , you will see a screen like this:

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Where to go from here?

Setup a CI/CD pipeline for your serverless project and let me know how it turned out . Check out for details instructions on how to get started and customize workflows.

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